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Key FeaturesWorld’s smallest lightest interchangeable lens full-frame camera 1Sony’s Exmor image sensor takes full advantage of the Full-frame format, but in a camera body less than half the size and weight of a full-frame DSLR.Full Frame 24.3 MP resolution with 14-bit RAW outputA whole new world of high-quality images are realized through the 24.3 MP effective 35 mm full-frame sensor, a normal sensor range of ISO 100 – 25600, and a sophisticated balance of high resolving power, gradation and low noise. The BIONZ ® X image processor enables up to 5 fps high-speed continuous shooting and 14-bit RAW image data recording.Fast Hybrid AF w/ phase-detection for DSLR-like focusing speedEnhanced Fast Hybrid auto focus combines speedy phase-detection AF with highly accurate contrast-detection AF , which has been accelerated through a new Spatial Object Detection algorithm, to achieve among the fastest autofocusing performance of any full-frame camera. First, phase-detection AF with 117 densely placed phase-detection AF points 3 swiftly and efficiently moves the lens to bring the subject nearly into focus. Then contrast-detection AF with wide AF coverage fine-tunes the focusing in the blink of an eye.Fast Intelligent AF for responsive, accurate, and greater operability with full frame sensorThe high-speed image processing engine and improved algorithms combine with optimized image sensor read-out speed to achieve ultra high-speed AF despite the use of a full-frame sensor.New Eye AF controlEven when capturing a subject partially turned away from the camera with a shallow depth of field, the face will be sharply focused thanks to extremely accurate eye detection that can prioritize a single pupil. A green frame appears over the prioritized eye when focus has been achieved for easy confirmation. Eye AF can be used when the function is assigned to a customizable button, allowing users to instantly activate it depending on the scene.Fully compatible with Sony’s E-mount lens system and new full-frame lensesTo take advantage of the lightweight on-the-go body, the α7 is fully compatible with Sony’s E-mount lens system and expanded line of E-mount compact and lightweight full-frame lenses from Carl Zeiss and Sony’s premier G-series.Direct access interface for fast, intuitive shooting controlQuick Navi Pro displays all major shooting options on the LCD screen so you can rapidly confirm settings and make adjustments as desired without searching through dedicated menus. When fleeting shooting opportunities arise, you’ll be able to respond swiftly with just the right settings.High contrast 2.4M dot OLED EVF for eye-level framingView every scene in rich detail with the XGA OLED Tru-Finder, which features OLED improvements and the same 3-lens optical system used in the flagship α99. The viewfinder faithfully displays what will appear in your recording, including the effects of your camera settings, so you can accurately monitor the results. You’ll enjoy rich tonal gradations and 3 times the contrast of the α99. High-end features like 100% frame coverage and a wide viewing angle are also provided.3.0" 921K dot LCD tilts for high and low angle framingThe tiltable 3.0” (921k dots) Xtra Fine™ LCD Display makes it easy to photograph over crowds or low to capture pets eye to eye by swinging up approx. 84° and down approx. 45°. Easily scroll through menus and preview life thanks to WhiteMagic™ technology that dramatically increases visibility in bright daylight. The large display delivers brilliant-quality still images and movies while enabling easy focusing operation.Simple connectivity to smartphones via Wi-Fi ® or NFCILCE-7/B α7 (Alpha 7) Interchangeable Lens Camera No other full frame, interchangeable-lens camera is this light or this portable. 24.3 MP of rich detail. A true-to-life 2.4 million dot OLED viewfinder. Wi-Fi ® sharing and an expandable shoe system. It’s all the full-frame performance you ever wanted in a compact size that will change your perspective entirely.Connectivity with smartphones for One-touch sharing/One-touch remote has been simplified with Wi-Fi®/NFC control. In addition to Wi-Fi support for connecting to smartphones, the α7 also supports NFC (near field communication) providing “one touch connection” convenience when transferring images to Android™ smartphones and tablets. Users need only touch devices to connect; no complex set-up is required. Moreover, when using Smart Remote Control — a feature that allows shutter release to be controlled by a smartphone — connection to the smartphone can be established by simply touching compatible devices.PC control w/ remote video capture controlRemote Camera Control allows you to control your α7 from your PC using a USB cable. Feature control has also been updated to include video capture control.14-bit RAW output for rich tonal gradation14-bit RAW image data of extremely high quality is outputted by the α7. This data fully preserves the rich detail generated by the image sensor during the 14-bit A/D conversion process. When developed with Sony’s Image Data Converter RAW development software, these images deliver the superb photographic expression and rich gradation that only 14-bit data can offer.New BIONZ® X image processing engineSony proudly introduces the new BIONZ® X image processing engine, which faithfully reproduces textures and details in real time, as seen by the naked eye, via extra high-speed processing capabilities. Together with front-end LSI (large scale integration) that accelerates processing in the earliest stages, it enables more natural details, more realistic images, richer tonal gradations and lower noise whether you shoot still images or movies.Full HD movie2 at 24p/60i/60p w/uncompressed HDMI® outputCapture Full 1920 x 1080 HD uncompressed clean-screen video files to external recording devices via an HDMI®connection in 60p and 60i frame-rates. Selectable in-camera A VCHD™ codec frames rates include super-smooth 60p, standard 60i or cinematic 24p. MP4 codec is also available for smaller files for easier upload to the web.Up to 5 fps shooting to capture the decisive momentWhen your subject is moving fast, you can capture the decisive moment with clarity and precision by shooting at speeds up to 5 frames per second. New faster, more accurate AF tracking, made possible by Fast Hybrid AF, uses powerful predictive algorithms and subject recognition technology to track every move with greater speed and precision.Multi-interface Shoe for flash and microphone flexibilityUnlike conventional cameras, the α7 features the advanced Multi-Interface Shoe that dramatically expands compatibility with Sony digital imaging accessories, thus raising the potential for photo/movie shooting.4K Still image output by HDMI® or WiFi® for viewing on 4K TVs8Enjoy Ultra High Definition slide shows directly from the camera to a compatible 4K television. The α7 converts images for optimized 4K image size playback (8MP). Enjoy expressive rich colors and amazing detail like never before. Images can be viewed via an optional HDMI® or WiFi®.TRILUMINOUS™ color outputs wider color gamut to compatible devicesTRILUMINOS™ Color technology, allows you to experience photos and movies in rich, natural colors on any TV equipped with a TRILUMINOS Display™. The expanded color gamut immerses you in those unforgettably colorful moments, from the complex shades in a shimmering blue sky to the delicate skin in a baby’s face.PlayMemories™ Camera Apps allows feature upgradesPersonalize your camera by adding new features of your choice with PlayMemories™ Camera Apps. Find apps to fit your shooting style from portraits, detailed close-ups, sports, time lapse, motion shot and much more. Use apps that shoot, share and save photos using Wi-Fi that make it easy to control and view your camera from smartphone, and post photos directly to Facebook or backup images to the cloud without connecting to a computer.11Image Data ConverterAdvanced features enable manipulation, conversion and management of full-resolution RAW images. You can expertly adjust exposure, white balance, tonal curves, saturation, contrast, hue and sharpness — as well as apply DRO and vignetting compensation. Bundled Remote Camera Control software also lets you remotely activate and deactivate still/ movie recording and control various camera settings from a PC.Vertical Grip CapableEnjoy long hours of comfortable operation in the vertical orientation with this sure vertical grip, which can hold two batteries for longer shooting and features dust and moisture protection.Mount AdaptorsMount any A-mount lens to the α7R with either the LA-EA3 or EA4 35mm full-frame compatible adaptors. The LA-EA4 additionally features a built-in AF motor, aperture-drive mechanism and Translucent Mirror Technology to enable continuous phase-detection AF. Both adaptors also feature a tripod hole that allows mounting of a tripod to support large A-mount lenses.Specifications1. Among interchangeable-lens cameras with an full frame sensor as of October 20132. Records in up to 29 minute segments.3. 99 points when an APS-C lens compatible with Fast Hybrid AF is mounted.7. Actual performance varies based on settings, environmental conditions, and usage. Battery capacity decreases over time and use.8. Requires compatible BRA VIA HDTV and cable sold separately.9. Auto Focus function available with Sony E-Mount lenses and Sony A-mount SSM and SAM series lenses when using LA-EA4 lens adaptor.。
a r X i v :0801.0451v 1 [a s t r o -p h ] 2 J a n 2008A cgi synthetic CMD calculator for the YY IsochronesP.Demarque 1,S.N.Virani 1,E.J.Murphy 1,2,J.-H.Woo 1,3,Y.-C.Kim 4&S.K.Yi 41Department of Astronomy,Yale University,New Haven,CT 06520-8101,USA 2Spitzer Science Center,California Institute of Technology,Pasadena,CA 91125,USA 3Department of Physics,University of California,Santa Barbara,CA 93106-9530,USA4Department of Astronomy,Yonsei University,Seoul 120-749,Korea ABSTRACT We describe a web-based cgi calculator for constructing synthetic color-magnitude diagrams for a simple stellar population (SSP)using the Yonsei-Yale (YY)isochrone data base.This calculator is designed to be used interactively.It creates quick look CMD displays in (B-V)and (V-I)colors.Stochastic ef-fects on the CMDs are included.Output in tabular form is also provided for special purpose displays,or for combining the CMDs of different stellar popula-tions.This research tool has applications in studies of the stellar content of our Galaxy and external systems.It provides an easy way to interpret the CMDs in resolved stellar populations.It offers the means to explore the dependence of the integrated properties of unresolved stellar systems on stellar parameters (ages,chemical composition,binarity)and on the characteristics of their parent population (IMF slope and mass range).1.IntroductionThis program creates a synthetic color-magnitude diagram (CMD)for a simple stellar population (SSP),i.e.for a stellar population of a given age and chemical composition,that obeys a specified initial mass function (IMF)based on the prescription by Park &Lee (1997).Stochastic effects on the CMD are included.As an additional feature,the presence of a population of unresolved binaries can be taken into account (Woo et al.2003).The code is designed for use with the Yonsei-Yale (YY)isochrones,and covers the pre-main sequence and hydrogen burning phases of evolution.The YY isochrones and luminosity functions are described in detail in papers by Yi et al.(2001,2003;Paper 1and Paper 3)and Kim et al.(2002;Paper2).Evolutionary tracks are available in Demarque et al.(2004; Paper4).The YY isochrone tables cover metallicities Z(heavy element content by mass)in the range0.0to0.08,and values ofαenhancement corresponding to[α/F e]=0.0,0.3 and0.6.Helium diffusion and convective core overshoot have been taken into account in calculating the evolutionary tracks.Thisfirst set of isochrones(Paper1)was for the scaled solar mixture.The completing sets(for twice and four-timesα-enhanced)were released in Paper2.Two significant features of these isochrones are that(1)the stellar models start their evolution from the pre-main sequence birthline instead of from the zero-age main sequence, and(2)the color transformation has been performed using both the tables of Lejeune et al. (1998),and the older,but now modified,Green et al.tables(1987).The web interface to the CMD calculator can be found at the two YY web sites:/demarque/yyiso.htmlIn addition,these two web sites provide links to the four YY papers listed above,and codes to interpolate between isochrones in age and chemical composition within the available parameter range.2.CMD calculator input parametersA number of input parameters must be defined in the construction of synthetic CMDs. The list of input parameters on the web interface is given below.The output CMD can be retrieved either in tabular or graphical form.•AlphaThis is the composition parameter[α/F e],which denotes the relative abundance by number with respect to the Sun ofαenriched nuclei in the chemical composition mixture.The notation is the usual logarithmic relative abundance with respect to the Sun.In this notation,the metallicity of a star is defined by[X/H]≡log(N X/N H)⋆−log(N X/N H)⊙(1) where N X and N H are the relative abundances by numbers of element X and of hy-drogen,respectively.The abundance ratio[α/F e]is defined correspondingly.InputTable1.The assumptions forα-enhancement Element[α/Fe]=0.0a[α/Fe]=+0.3[α/Fe]=+0.6a The scaled-solar abundance ratios of metals are taken from Grevesse&Noels1993.Note.—The abundance of the elements in logarithmic scale,log N el/N H+12,where N el is the abundance by number.values ofαmust be in the range0.0to0.6(by definition,α=0corresponds to the solar mixture).•MetallicityThe metallicity parameter Z for the synthetic CMD.Z is the mass fraction of the heavy elements as usually defined in stellar interior calculations(i.e.X+Y+Z= 1,where X and Y are the mass fractions of H and He).The parameter Z should be in the range(near)0.0to0.08(Note that Z≡0is not allowed).Table2provides a conversion between Z and[F e/H]for different values of[α/F e].•AgeThe age of the stellar population(in Gyr)for the calculated synthetic CMD.•Number of starsThe total number of stars N to be used in the calculation of the synthetic CMD.A maximum of100,000stars is allowed for the value of N.The total number of stars N in the synthetic CMD is defined as:N=C M upper M lower M−(x+1)dM(2)where x is the IMF slope,and M upper and M lower define the range of masses included in the integration.The definition of x is the same as in the review by Tinsley(1980). The YY luminosity functions are tabulated for x=-1,1.35and3.The x=1.35power law corresponds to the Salpeter IMF(1955).C is a normalization constant.The YY tables are normalized to1000stars in the mass range0.5-1.0M⊙.•IMF slopeChosen value of the IMF slope x defined in eq.(2)(Note that x=0).•IMF upper limitThe upper mass limit M upper of the IMF in eq.(2),in solar units.•IMF lower limitThe lower mass limit M lower of the IMF in eq.(2),in solar units.•ISEEDThe random number generator seed to be used for the synthetic CMD calculations. Varying ISEED illustrates the importance of stochastic effects in CMDs for a given set of input parameters.A knowledge of ISEED allows the user to retrieve previously made synthetic CMDs.•Binary fractionThe fraction of binary stars for the calculated synthetic CMD,given as a number between0.0and1.0.•qmassMass fraction for binary stars,given as a number between0.0and1.0.3.ExamplesA series of examples are now presented that illustrate the effect of varying the input parameters one at a time.Fig.1shows the reference synthetic CMD against which other CMD examples can be compared,The following input reference parameters were adopted:REFERENCE PARAMETERST he parameter alphaFig.3shows the effect of varying[α/F e]from0.to0.3.Table2,taken from Paper2, lists the corresponding changes in total Z.The reader is referred to Paper2for a discussion of the different effects of variations in[α/F e]in low-Z and high-Z mixtures.Relative H and He abundancesNote that in the YY isochrone tables,the helium content by mass Y is keptfixed for a given value of Z.In all examples given here,(∆Y/∆Z)=2has been assumed.This corresponds to Y=0.238for Z=0.004,and to Y=0.27for Z=0.02.•Varying the ageIn Fig.4,the age has been changed from8.0to5.0Gyr.•Varying the total number of stars NIn Fig.5,the value of N is changed from1000to500.As expected,stochasticfluctu-ations become larger as N decreases.•Varying the mass function parametersThe distribution of stellar masses in the synthetic model depends on three parameters, the IMF slope x and the upper and lower masses,M upper and M lower respectively. The effect of changing the IMF slope from x=1.35to0.5is shown in Fig.6.The effects of changing independently the upper and lower mass limits to3.0M⊙and0.7M⊙are shown in Fig.7and Fig.8,respectively,all other parameters are as given in the reference parameter list.•ISEEDVarying ISEED highlights the role of stochastic effects.For small N,stochastic effects become significant in rapid evolutionary phases.For example,the two CMDs shown in Fig.9and Fig.10are based on the same set of input parameters(except that ISEED=299and128,respectively).This introduces an uncertainty in the integrated energy distribution of the stellar population.•Varying the binary star contentThe presence of unresolved binaries can also affect the CMD significantly.Fig.1shows a synthetic CMD that does not include binaries.Fig.11and Fig.12are plotted for a binary fraction of0.2,but with the different mass fractions qmass=0.3and 0.7,respectively.The synthetic cluster CMDs by Woo et al.(2000)illustrate the importance of including binary systems,particularly in moderately rich stellar systems.4.ConclusionsThis note describes a web-based CMD calculator designed for the study of stellar popu-lations in the Galaxy and distant stellar systems.This web based calculator,which is based on the YY isochrones,is a useful tool for studies of resolved star clusters,and for explo-rations of the sensitivity of the integrated light of stellar systems to stellar and population parameters.Future versions of this calculator will be based on a more comprehensive YY database covering an extended range of helium abundances,the inclusion of helium burning phases of evolution,often very significant in the CMDs of stellar systems,and the availability of a simple spectral energy distribution(SED)library.This research was supported in part by NASA grant HST-GO-10505.03-A.5.ReferencesDemarque,P.,Woo,J.-H.,Kim,Y.-C.&Yi,S.2004,ApJS,155,667(Paper4)Green,E.M.,Demarque,P.,&King,C.R.1987,The Revised Yale Isochrones and Lumi-nosity Functions(New Haven:Yale Univ.Obs.)Grevesse,N.,&Noels,A.1993,in Origin and Evolution of the Elements,ed.N.Prantzos, E.Vangioni-Flam,&M.Cass´e(Cambridge:Cambridge Univ.Press)Kim,Y.-C.,Demarque,P.,Yi,S.&Alexander,D.R.2002,ApJS,143,499(Paper2) Lejeune,Th.,Cuisinier,F.&Buser,R.1998,A&A,130,65Park,J.-H.&Lee,Y.-W.1997,ApJ,476,28Salpeter,E.E.1955,ApJ,121,161Tinsley,B.M.1980,Fund.Cosmic Phys.,5,287Woo,J-H.,Gallart,C.,Demarque,P.,Yi,S.,Zoccali,M.2003,AJ,125,754Yi,S.,Demarque,P.,Kim,Y.-C.,Lee,Y.-W.,Ree,C.H.Lejeune,Th.&Barnes,S.2001, ApJS,136,417(Paper1)Yi,S.,Kim,Y-C.,&Demarque,P.2003,ApJS,144,259(Paper3)Table2.Conversion from[Fe/H]to Z[Fe/H]Z[α/Fe]=0.0[α/Fe]=+0.3[α/Fe]=+0.6。
阅读的好处英文作文阅读是从视觉材料中获取信息的过程。
下面是店铺给大家整理的一些英语范文，供大家参阅!阅读的好处英文作文篇1When I'm free or in trouble, I always take out a book and read quietly. In no time, I've put my heart into it so that I'll forget all the troubles. It's in this way that I've formed the habit of reading in any time.Little boys as I was, I was interest in picture books and storybooks. I was struck by them. No sooner had I entered the middle school than I began to read novel, plays, and essays and so on. I found I could get much from them. Little by little I took great interest in literature and last term I won the first prize in the composition contest among middle-school students in Zhe Jiang.Reading “The Emperor's New Clothes”, I had to let out a burst of laughter over his fool. “The Little Match Girl” couldn't keep me from crying for her misery. “Robinson Crusoe” took me into a strange world full of danger. And I was also deeply impressed by Helen Keller's patience and perseverance… Besides these, books also tell me other thing -how to be a man and how to tell the difference between right and wrong. In a word, good books can make me know what I didn't before. So I think of a good book as my best friend.I'll never forget this famous saying,“Good books are best friends who never turn their backs upon us.”阅读的好处英文作文篇2The more books you read, the better your life will be. If you don't believe me, please consider these twelve compelling reasons to read more books.你读的书越多，你的生活就会越好。
标题：Exploring the Mysterious Universe - A Journey for the Curious MindIn the vast and infinite expanse of the universe, there lies a world of wonders and mysteries that have fascinated humans for generations. From the twinkling stars above us to the distant galaxies beyond imagination, the universe is a never-ending source of curiosity and exploration. Join me as we embark on a journey through this mysterious universe, discovering its secrets and wondering about its vastness. The universe is vast and beyond comprehension. It is estimated that there are over 200 billion galaxies in the universe, and each galaxy contains billions of stars. Just imagine the magnitude of it! It's like a vast ocean of stars, with our planet Earth being just a tiny speck inthis vast cosmos.One of the most fascinating aspects of the universe is the phenomenon of black holes. These mysterious objects have a strong gravitational pull that is so powerful that nothing, even light, can escape from them. Scientists are still trying to understand the properties and behavior ofblack holes, but what they have discovered so far is truly mind-boggling.Another remarkable feature of the universe is the beauty and diversity of galaxies. Galaxies like the Milky Way are vast collections of stars, dust, and gas that form patterns and shapes that are truly breathtaking. The swirling arms of galaxies and the bright centers filled with stars create a stunning visual display that is a testament to the beauty and complexity of the universe.But the universe is not just about beauty and mystery. It is also a place of discovery and learning. Astronomers and scientists use telescopes and advanced technology to observe and study the universe, trying to understand its origin, evolution, and future. Their findings have not only changed our understanding of the universe but have also led to new discoveries and advancements in science and technology.As we explore the universe, we also discover the potential for life beyond Earth. The existence of planets and solar systems similar to our own raises the question of whether there is other life in the universe. This questionhas fascinated humans for centuries, and the search for extraterrestrial life continues to be a major focus of space exploration.In conclusion, the universe is a vast and mysterious place that continues to inspire and fascinate humans. It is a never-ending source of discovery and learning, and as we continue to explore it, we discover more about ourselves and our place in the universe. So, let's keep our minds open to the wonders of the universe and continue to ask questions, explore, and discover.**宇宙探索的神秘之旅——好奇心的征途**在宇宙这片广阔无垠、深邃神秘的领域中，存在着无数令人着迷的奇迹。
描写宇宙的唯美句子英文版(篇一)1. The universe is a breathtaking masterpiece, decorated with twinkling stars and vibrant galaxies.2. In the depths of space, celestial bodies dance in perfect harmony, creating an ethereal symphony.3. The cosmic expanse is an infinite canvas, pXXnted with celestial hues of indigo, crimson, and gold.4. Stardust whispers tales of the universe's birth, carrying the secrets of creation through time and space.5. Nebulas bloom like cosmic flowers, their radiant colors pXXnting the night sky with ethereal beauty.6. The Milky Way stretches across the night, a river of shimmering stars guiding our celestial journey.7. Planets orbit gracefully, like cosmic dancers waltzing through the vastness of space.8. As the sun sets on distant horizons, the universe reveals a tapestry of breathtaking twilight hues.9. Meteor showers cascade, pXXnting the darkness with streaks of silver and gold, like celestial fireworks.10. Galactic clusters form celestial cities, where stars of all sizes and colors converge in a dazzling display.11. As comets streak across the sky, they leave behind traces of celestial wonder and awe.12. The immensity of space stretches beyond our comprehension, a reminder of humanity's infinitesimal presence.13. Celestial bodies collide, birthing new worlds and scattering stardust dreams across the universe.14. Beyond our Earthly confines, galaxies swirl like cosmic whirlpools, creating mesmerizing patterns of light.15. Shooting stars grant wishes, carrying our hopes and dreams to the farthest reaches of the universe.16. Lunar eclipses unveil a rare cosmic ballet, where shadows and light intertwine ina celestial dance.17. The silence of space echoes with whispered secrets, inviting us to explore its infinite mysteries.18. The universe is a cosmic tapestry, woven with threads of time and stitched with constellations of wonder.19.Like a celestial symphony, the universe's harmonious melodies resonate through the endless expanse.20. Saturn's rings, a celestial jewel, adorn the planet with elegance and grace.21. The aurora borealis, a celestial light show, pXXnts the night sky with vibrant ribbons of color.22. Supernovae burst forth in cataclysmic eruptions, scattering the remnants of stars like cosmic confetti.23. The universe's beauty lies in its juxtaposition of immense darkness and shimmering light.24. Mars, the red planet, beckons us with its mystique and potential for extraterrestrial discovery.25. Jupiter, with its swirling storms and colossal presence, reigns as a celestial giant in the solar system.26. The universe is a celestial stage, where stars take their places and the cosmos performs its grand spectacle.27. As galaxies collide, they create breathtaking collisions of light, cosmic fireworks illuminating the darkness.28. The twinkle in a child's eye mirrors the distant stars, reminding us that we are all made of stardust.29. The universe's grandeur reminds us of our smallness, yet inspires us to seek answers beyond our own planet.30. The moon, a celestial companion, shines a soft glow upon the Earth, bathing it in its ethereal light.31. Solar flares erupt in radiant bursts, illuminating the solar system with celestial fire.32. The universe's beauty lies not just in its grandeur, but in the intricacies of its smallest particles.33. As galaxies collide, they release cosmic ripples, forever changing the fabric of the universe.34. The universe is a kaleidoscope of light, where stars and planets form mesmerizing patterns across the sky.35. Celestial bodies, like ancient storytellers, carry the history of the universe within their cosmic depths.36. The Andromeda Galaxy, an enigmatic neighbor, unveils the secrets of an extragalactic world wXXting to be explored.37. As we gaze into the depths of space, we catch a glimpse of the universe's eternal dance of creation and destruction.38. The constellations, celestial maps etched upon the night sky, guide our navigation through the vastness of space.39. The universe's vastness reminds us of our boundless potential, urging us to reach for the stars and explore the unknown.40. The cosmos, a cosmic kaleidoscope, pXXnts the universe with awe-inspiring complexity and beauty.41. The universe's majesty is captured in a single moment, where the night sky becomes a celestial masterpiece.42. The interstellar medium, a cosmic cloud of gas and dust, births new stars and nurtures the universe's ongoing evolution.43. Lyrid meteors streak across the sky, like cosmic brushstrokes adding splashes of brilliance to the canvas of night.44. The darkness of space offers a backdrop for the brilliance of the universe, a stage for celestial wonders to unfold.45. The universe's expanses span billions of light-years, a testament to its boundless and unfathomable nature.46. Solar eclipses cast a symphony of shadows upon our world, as celestial bodies align in a celestial dance.47. The universe's beauty lies not only in its splendor, but in the silent solitude it grants to those who dare to explore its depths.48. Time dilates in the cosmic expanse, blurring the boundaries between past, present, and future, as the universe unfolds.49. Like a cosmic lighthouse, pulsars emit beams of celestial light, guiding our way through the vastness of space.50. The universe reflects the awe-inspiring power of creation, reminding us of the forces that shape both the cosmos and our own existence.51. The celestial ballet of the planets offers a glimpse into the celestial mechanics that govern the universe's intricate dance.52. The beauty of the universe lies not only in its visual splendor but in the symphony of cosmic vibrations that resonate through its depths.53. The universe's labyrinths of dark matter captivate our imaginations, challenging us to understand the invisible forces that shape the cosmos.54. The celestial harmony of celestial bodies creates an intoxicating rhythm that echoes through time and space, resonating with the planets and stars alike.55. The distant glow of distant galaxies serves as a cosmic reminder of the infinite possibilities that lie beyond our own solar system.56. The universe's ethereal auroras dance across the night sky, revealing the cosmic choreography of charged particles in Earth's magnetic field.57. The vastness of space mirrors the depths of the human soul, beckoning us to explore our inner universe in tandem with the cosmic expanse.58. The cosmos pXXnts its own portrXXt through the lens of the Hubble Space Telescope, capturing the universe's ever-evolving grandeur in stunning detXXl.59. Like cosmic clockwork, the celestial bodies of our solar system align in synchrony, creating celestial events that captivate our collective gaze.60. The universe's beauty resides not only in the grandeur of its most prominent celestial bodies but in the subtlety of its hidden wonders that wXXt to be discovered.描写宇宙的唯美句子英文版(篇二)Stunning Sentences Depicting the Beauty of the Universe in English: Over 50 Captivating Phrases1. The stars danced in the cosmic ballet of the night.2. The moon whispered secrets to the infinite darkness.3. A canvas of stardust pXXnted across the night sky.4. The galaxies intertwined, creating a celestial symphony.5. Nebulas illuminated the deep space with their ethereal glow.6. Planets sXXled like celestial sXXlors in the sea of the universe.7. The sun radiated its golden warmth, nurturing distant worlds.8. Meteor showers rXXned down like nature's fireworks.9. The Milky Way stretched its arms across the vastness of the cosmos.10. Constellations formed intricate patterns, telling tales of ancient myths.11. Astronomers unveiled the mysterious beauty hidden beyond our sight.12. Asteroids became wanderers, floating XXmlessly through the endless expanse.13. Shooting stars granted wishes, lighting up dreams in the night.14. Solar flares danced and flickered like flames of cosmic passion.15. Black holes swallowed galaxies, leaving behind a void of eternal nothingness.16. The universe stood as a majestic tapestry woven with celestial threads.17. The Aurora Borealis pXXnted the sky with hues of green and pink.18. Celestial bodies whispered secrets in a language known only to the cosmos.19. The universe's silence spoke volumes, echoing the magnitude of its existence.20. Cosmic dust particles settled, creating the building blocks of life.21. Satellite images unveiled the intricate patterns of Earth seen from above.22. The veil of the night sky lifted, revealing the wonders of the universe.23. Solar eclipses mesmerized, grounding humanity in the celestial dance.24. Galaxies collided, birthing new worlds and possibilities.25. The beauty of the universe humbled the soul, igniting a sense of wonder.26. Time stood still amidst the grandeur of cosmic phenomena.27. Celestial bodies, like celestial angels, guided humanity through the night.28. Saturn's rings glimmered like jewels adorning a cosmic crown.29. The universe's vastness mirrored the boundless potential within us all.30. Planets danced in perfect harmony, an intricate cosmic choreography.31. The night sky whispered secrets that only the stars could hear.32. Supernovas exploded, scattering stardust across the universe.33. The moon's gentle glow soothed the restless hearts of wanderers.34. The universe's symphony resonated within the depths of the soul.35. Asteroid belts formed cosmic highways, guiding explorers through the unknown.36. Stars twinkled like diamonds, igniting the curiosity of dreamers.37. Meteorites crashed, leaving behind a cosmic fingerprint in time.38. The celestial canopy revealed the secrets of the universe to those who dared to look up.39. Planetary alignments pXXnted celestial masterpieces across the sky.40. The vastness of the cosmos humbled mortal beings, reminding them of their insignificance.41. Shooting stars streaked through the night, leaving trXXls of cosmic dreams.42. Astronomical discoveries unveiled the magnificent complexity of the universe.43. The beauty of the universe anchored the soul in a sea of tranquility.44. Supernovas erupted like fireworks, celebrating the majesty of existence.45. Satellite imagery captured the fragile beauty of our blue planet from above.46. The universe's rhythm echoed in the hearts of stargazers.47. Jupiter's swirling storms mirrored the chaos and beauty of life.48. The expanse of the universe beckoned the human spirit to explore its mysteries.49. The cosmic ballet pXXnted the sky with swirls of colors and shapes.50. The intricate web of galaxies wove connections between the stars and the souls who admired them.注意：本文所提供的内容仅为创作用途，切勿将其中的部分或整个内容复制到其他地方，包括网站、博客或其他类型的渠道，以免造成未经授权的侵权行为。
Opti-Check™Handheld FluorometerNovember 11, 2011 P/N: 998-0861 Revision ATURNER DESIGNS 845 W. Maude Ave. Sunnyvale, CA 94085 Phone: (408) 749-0994 FAX: (408) 749-0998Table of Contents1. Introduction1.1 Description 31.2 Quick View Diagram 31.3 Inspection and Setup 31.4 General Information, Precautions & Cleaning 42. Instrument Specifications2.1 General Specifications 52.2 Optical Configurations for Applications 52.3 Cuvette Information 53. Instrument Operation and Calibration3.1 Instrument Power Up 63.2 Detection Channel Configuration 6Overview 6 3.3 CalibrationProcedure 7 3.4 Calibration3.5 Sample Analysis 83.6 Diagnostic Information 84 Sample Analysis Guidelines4.1 Handling Samples 9Samples 9 4.2 Positioning4.3 Linear Range and Quenching 9Considerations 10 4.4 Temperature4.5 DataQuality 10 5 Applications5.1 Fluorescein 115.2 PTSA 116 Quick Diagnosis Guides6.1 Power / Battery / Screen Issues 126.2 Reading and Calibration Issues 137. Warranty7.1 Terms 14Service 14 7.2 Warranty7.3 Out of Warranty Service 151 Introduction1.1 DescriptionThe Opti-Check is a small, lightweight, highly durable handheld fluorometer ideal for quick measurements in the field. Dual-channel capability enables measurement for both cooling tower and boiler system applications. Simple to operate, the Opti-Check is a perfect tool for system verification. The Opti-Check can be configured with two channels: Fluorescein, PTSA or both.1.2 Quick View Diagrams1.3 Inspection and Setup1.3.1 InspectionUpon receiving your instrument, please inspect everything carefully and make sure allaccessories are present. All shipments include:•The Opti-Check•The User’s Manual on CD• 4 - AAA batteries•Cuvettes – Qty 4• Storage Pouch1.3.2 SetupBefore the Opti-Check can be used, the supplied batteries must be installed.1. On the back side of the instrument, remove the battery panel by loosening the centerscrew and then gently pulling on the screw. There is some resistance due to the o-ring which is used for watertight sealing (see Section 1.2 for diagram).2. Install the 4 - AAA batteries and verify the batteries are positioned correctly.3. Replace the battery panel and press it down into position.4. Hold the battery panel down in place and gently tighten the screw until it is snug.Do not over tighten the screw.Note: If the battery panel is very difficult to press down or remove, you can apply a small amount of silicon-based grease to lubricate the o-ring as needed.1.4 General Information, Precautions and Cleaning•The sample compartment cannot accept 10 mm square cuvettes because the cuvette wall thickness exceeds the 12 mm maximum outer dimension that the Opti-Check canaccept. The 10 mm size is the internal dimension of the cuvette and some plasticcuvettes may be too large.•Do not force oversized cuvettes into the sample compartment. This can damage the sample compartment. If the cuvette does not easily fit down inside the Opti-Check you will need to purchase different cuvettes.•Use caution around solvents because they may attack the plastic case of the Opti-Check.•If a sample is accidentally spilled inside the Sample Compartment, invert the Opti-Check to drain out the excess liquid. Then wipe the inside area dry with a clean soft towel ortissue.•If extra cleaning is needed, use a mild detergent to dampen the towel for cleaning.•Do not submerge the Opti-Check in water.•Do not expose the Opti-Check to temperatures outside the specified range of5 to 40 °C or damage may occur to the unit that will not be covered under warranty.2 Instrument Specifications2.1 General SpecificationsSpecification DescriptionSize 1.75” x 3.5” x 7.25”(4.45cm x 8.9cm x 18.4cm)Weight 13.9oz(0.4kg)Dynamic range 3 orders of magnitudeResolution 12bitsLCD Display 2 x 16 charactersCase Meets IP 67 Standard; dustproof and watertight Temperature 41-104 °F; 5-40 °CDetector PhotodiodeCalibration Type Single-point and blankError message Low battery, High blankCuvette Type MethacrylateWarm Up Time 5 secondsAuto Power Off After 3 minutes of inactivity2.2 Optical Configurations for Application (Channel)Application Light SourceMinimumDetection LimitLinear Range Excitation EmissionTemperatureCoefficientsFluorescein Dye Blue LED < 1 ppb 0 - 400 ppb 485 nm 540 nm0.0036/°CExponentialPTSA UV LED < 1 ppb 0 – 1000 ppb 365 nm 400 nm -0.00126/°C Exponential2.3 Cuvette informationCuvette type Size Usage Part No.Methacrylate plastic 10 mm Square(height 44.5 mm)Required for UV (< 400 nm), works for all applications.Do NOT use with solvents7000-9593 Instrument Operation and Calibration3.1 Instrument Power UpTo turn on the Opti-Check, press the <ON/OFF> button. After a 5 second warm up, the Opti-Check is ready for operation.Pressing the <ON/OFF> button again will turn the unit off or if left idle for 3 minutes the unit will turn itself off to save battery power.A set of new batteries will last for over 1,000 sample readings. If the batteries have lowpower or are not positioned properly, the following warning message will be displayed – “Batt Level < 20% !! Caution !!”.The contrast of the display can change with temperature and will get lighter as the unit gets colder. The contrast can be easily adjusted. Press the ↑ arrow button to darken thecontrast and press the ↓ arrow to lighten the display contrast.3.2 Detection Channel ConfigurationThe Opti-Check can be configured with one or two optical channels. To identify theconfiguration look at the label on the back side of the Opti-Check.The <A/B> button allows the user to toggle between the 2 channels. The display will show a label in the lower left corner of the Home screen to identify which channel is activated.3.3 Calibration OverviewThe Opti-Check can be calibrated using a Primary standard. A Primary Standard is one that contains the same fluorescent material that you are measuring in your unknown samples.The Opti-Check will give an actual quantitative concentration reading when a primarystandard of known concentration is used for calibration.The standard and samples must be in the linear detection range to get accurate quantitative results. Refer to Section 5.3 for more details about the linear range and quenching of the samples.For Dye tracing applications the calibration is normally performed with a primary standard made from the same dye that is being used for the testing. The primary standard will either be made to a known concentration, typically in ppb or µg/L units, or to a known dilution factor. Ideally the Primary Standard and Blank samples used for calibrating will be made with the same water the tests are being performed in.3.4 Calibration ProcedureIt is recommended for best accuracy, that you always calibrate before performing yoursample analysis. The Opti-Check will save the calibration settings for each channel until a new calibration is performed.If the temperature of your samples or the Opti-Check changes significantly, the readings may show a small shift and in this case, you should consider recalibrating.The Opti-Check is designed with “ambient light rejection”. The black sample compartment cover does NOT need to be closed when calibrating or reading samples.The orientation and cleanliness of the cuvettes can have an impact on the accuracy of your results. Refer to Section 4, Sample Analysis Guidelines for information to help ensure the best results for your analysis.3.4.1 Assign a Calibration Standard Value.This defines the numeric value that you want the standard to read. For example, if you calibrate with a primary standard that has a concentration of 100ppb, then you will setthe value to 100 and the implied unit of measure will be in ppb.3.4.1.1 Press the <STD VAL> button.3.4.1.2 Use the ↑ and ↓ arrow buttons to set the standard value. Pressing the arrowbutton once quickly will make a small incremental change to the value. Holdingeither arrow button will allow you to change the value using fast scrolling.3.4.1.3 When finished, Press the <ENT> or <ESC> button to accept the value and toreturn to the Home screen.3.4.2 Perform the Calibration.3.4.2.1 Press the <CAL> button.3.4.2.1 Press <ENT> to start the calibration.3.4.2.3 Insert your blank sample and press <ENT>. The Opti-Check will average thereading for 10 seconds and set the blanking zero point.3.4.2.4 Insert the standard sample and press <ENT>. The reading is averaged for 10seconds and the Standard Calibration value is set.3.4.2.5 Press <ENT> when the calibration is complete to accept the calibration. If<ENT> is not pressed within 10 seconds, you will be asked if you want to abortthe calibration. Press the ↑ or ↓ arrow button to abort or accept the calibrationrespectively.If at anytime during steps 1-4 you want to stop the calibration, press <ESC>.This will return you to the Home screen and will default the instrument to theprevious calibration.3.4.3 Calibration CheckOnce the Opti-Check calibration is accepted, press the <DIAG> button to see whatyour standard to blank ratio is. The standard to blank ratio is defined as the %FSblank as compared to the %FS standard. The %FS signal should be at least 5 timeslarger than the %FS Blank. It should be between 5 and 30.•If your %FS std:%FS blk ratio is greater than 30, dilute your CalibrationStandard accordingly and recalibrate. Check the ratio again.•If your ratio is less than 5 you'll have to find a different standard for calibration.•If your ratio falls between 5 and 30 after the initial calibration then you can start measuring samples.Analysis3.5 Sample1. Insert your sample. The Opti-Check is designed with “ambient light rejection”. Theblack sample compartment cover does NOT need to be closed when reading samples.The orientation and cleanliness of the cuvettes can have an impact on the accuracy ofyour results. Refer to Section 5 for more details.2. Press the <READ> button. The instrument will measure and average the fluorescencesignal for 5 seconds.3. The reading result will be displayed on the top line of the Home screen.4. The top left corner will then display “WAIT” for 5 seconds. Once “WAIT” disappears,another sample reading can be performed.Information3.6 Diagnostic1. Press <DIAG> to access the diagnostic screens.2. Press <ENT> to toggle to the %FS (Full Scale) values for the blank (Blk) and standard(STD) calibration points. The STD value should be at least 5 times larger than the Blkvalue to ensure consistent results. This is often referred to as the Standard to BlankRatio.3. Press <ESC> when finished to return to the Home screen.4 Sample Analysis Guidelines4.1 Handling Samples4.1.1 Take care not to spill samples into the sample chamber. Wipe up any spillspromptly.4.1.2 The cuvette MUST BE DRY on the outside when taking readings. Any moisture orcondensation on the outside of the cuvette can affect the reading.4.1.3 Fill the cuvette with at least 2mL solution volume or at least 2/3 full. Significant errorin the readings can result if the cuvette contains less than this minimum volume.4.1.4 The Opti-Check is very sensitive and even small amounts of material from a previoussample may contaminate the sample and result in errors. Use a clean cuvette for allreadings. If you are using the same cuvette for your samples it is very important thatyou thoroughly clean the cuvette between samples. A good way to confirm thecuvette cleanliness is to read a blank solution. If the reading is higher than thenormal blank reading, the cuvette is not clean.4.1.5 Any bubbles in the sample will affect the readings. Take care not to introducebubbles into samples. Remove any bubbles by lightly tapping with your finger on theoutside cuvette wall or cover the top of the cuvette and tilt the sample to helpdissipate bubbles.4.2 Positioning SamplesThe orientation of the cuvette in the sample compartment can give slightly different readings especially for low concentration samples. This is due to variations in the walls of the cuvette that are not readily visible to the eye. We recommend that the cuvette be marked at the top on one side and positioned in the sample compartment the same way each time for best results.4.3 Linear Range and QuenchingThe linear range is the concentration range in which the readout of the Opti-Check is directly proportional to the concentration of the fluorophore in the sample. The linear range begins with the lowest detectable concentration and spans to an upper limit concentration that is dependent on the properties of the fluorescent material and the cuvette optical path length.For Fluorescein dye in the 10 mm square cuvette, the upper limit of linearity is approximately 400 ppb.At concentrations above this upper limit, the fluorescence reading will not increase at a linear rate in comparison to the change in concentration. At concentrations 10 times higher than the upper limit, the readings will start to decrease even though the sampleconcentration is increasing.This effect is known as "sample quenching" and is due to light absorption losses in thesample. See the Figure 1 graph below.When you start to see visual color in the sample, this is an indicator that the sample may be above the upper limit of linearity. The linearity can be verified by diluting a sample 1:1 or another convenient dilution ratio. If the sample is within the linear range, the reading will decrease in direct proportion to the dilution. If the reading does not decrease in directproportion to the dilution or if the reading increases, the original sample concentration was above the linear range.Figure 1. Linearity and Calibration Response Curve4.4 Temperature ConsiderationsFluorescence is temperature sensitive. As the temperature of the sample increases, the fluorescence decreases. For best accuracy make sure your samples are at the sametemperature as the calibration standard. If you have the ability to measure sampletemperature, a temperature coefficient may be applied to your measurements, see section2.2.4.5 Data QualityThe Opti-Check is only as accurate as the standards that are used to calibrate it. This is why it is important to take care when preparing standards, samples, and blank. One should follow good laboratory practices when preparing all solutions and samples.5 Applications5.1 FluoresceinFluorescein is a fluorescent tracer dye that provides an accurate, cost effective method for monitoring industrial boiler applications. Fluorescein dye can be detected using the Blue channel on the Opti-Check between 485-540nm. The linear detection range is 0 to 400 ppb (active ingredient) in potable water.Turner Designs offers Fluorescein Dye (PN 10-508) Calibration standard 10 ppb andFluorescein Dye (PN 10-509) Calibration standard 400 ppb.5.2 PTSAPTSA is a fluorescent tracer dye that measures in the UV range on the Opti-Check between 365-400nm. It can provide an accurate, cost effective method for monitoring industrial cooling tower applications and it can also be used as a standard for UV sensors. The linear detection range is 0 to 1000 ppb.Turner Designs offers PTSA (PN 10-608) Calibration standard 100 ppb and PTSA (PN 10-609) Calibration standard 400 ppb.6 Quick Diagnosis Guide6.1 Power / Battery / Screen IssuesThe Opti-Check is, generally, a trouble-free solid-state instrument. However, there have been a few issues reported that can easily be diagnosed and/or resolved in the field. Please use this guide to address some common Power / Battery / Screen Issues:6.2 Reading and Calibration IssuesPlease use this guide to address some common Reading / Calibration Issues.7 Warranty7.1 TermsTurner Designs warrants the Opti-Check Fluorometer and accessories to be free fromdefects in materials and workmanship under normal use and service for a period of 12months from the data of shipment from Turner Designs, with the following restrictions:•Turner Designs is not responsible for replacing parts damaged by accident or neglect.Your instrument must be installed according to instructions in the User’s Manual.Damage from corrosion is not covered. Damage caused by customer modification of the instrument is not covered.•This warranty covers only Turner Designs products and is not extended to equipment used with our products. We are not responsible for accidental or consequentialdamages, except in those states where this limitation is not allowed. This warranty gives you specific legal rights and you may have other rights which vary from state to state.•Damage incurred in shipping is not covered.7.2 Warranty ServiceIf you purchased your Opti-Check Fluorometer from one of our partners you need to contact them for service.If you purchased your instrument directly from Turner Designs and need to obtain service during the warranty period, please take the following steps:7.2.1 Write, email, or call the Turner Designs Technical Support department and describeas precisely as possible the nature of the problem.Phone: 1 (877) 316-8049Email: *************************7.2.2 Carry out any adjustments or tests as suggested by the Technical SupportDepartment.7.2.3 If proper performance is not obtained you will be issued a Return Authorizationnumber (RMA). Package the unit, write the RMA number on the outside of theshipping carton, and ship the instrument, prepaid, to Turner Designs. If the failure iscovered under the warranty terms, the instrument will be repaired and returned freeof charge, for all customers in the contiguous continental United States.7.3Out-of-Warranty ServiceFollow steps for Warranty Service as listed above. If our Technical Support department can assist you by phone or correspondence, we will be glad to, at no charge. Repair service will be billed on a fixed price basis, plus any applicable duties and/or taxes. Shipment to Turner Designs should be prepaid. Your bill will include return shipment freight charges.Address for Shipment:Turner Designs845 W. Maude AvenueSunnyvale, CA 94085。
太空风景描述英文作文初中Title: A Journey Through Space: Describing Cosmic Landscapes。
Space, the final frontier, holds within its vast expanse a beauty beyond comprehension. As we embark on a journey through the cosmic landscapes, we are greeted by sights that inspire awe and wonder, each one more breathtaking than the last.First, let us venture into the heart of a nebula, where clouds of gas and dust dance gracefully amidst the darkness of space. The colors here are like a painter's palette, with hues of pink, blue, and purple swirling together in a mesmerizing display. Bright stars peek through the mist, casting a gentle glow upon the celestial canvas.Moving further into the cosmos, we encounter the majestic beauty of a spiral galaxy. Spiral arms stretch outwards, adorned with clusters of stars and nebulae,creating a scene of unparalleled grandeur. In the center, a supermassive black hole lurks, its gravitational pull shaping the very fabric of space-time around it.As we continue our journey, we come across the enigmatic terrain of a planetary system. Here, we witness the diverse landscapes of distant worlds, each one uniquein its own right. Mountains soar towards the heavens, their peaks dusted with snow and ice. Vast plains stretch out as far as the eye can see, dotted with craters and valleys carved by ancient impacts. And on some planets, oceans of liquid methane shimmer under the light of distant stars, their depths hiding untold mysteries.But perhaps the most awe-inspiring sight of all is the cosmic ballet of a supernova explosion. In a brilliant burst of light and energy, a dying star collapses in on itself, unleashing a shockwave that reverberates throughout the cosmos. For a brief moment, the night sky isilluminated with the brilliance of a thousand suns, casting shadows across the vastness of space.Yet amidst the beauty and wonder of the cosmos, thereis also a sense of humility. We are but specks of dust in the face of such grandeur, mere observers in the theater of the universe. And yet, it is this very sense of insignificance that fills us with awe and wonder, reminding us of the boundless possibilities that lie beyond the confines of our own world.In conclusion, the space is a realm of unparalleled beauty and majesty, where the wonders of the cosmos unfold in an endless symphony of light and color. From theswirling clouds of a nebula to the explosive fury of a supernova, each sight serves as a reminder of the vastness and complexity of the universe in which we reside. And as we gaze upon these cosmic landscapes, we are filled with a sense of awe and wonder, humbled by the sheer magnitude of it all.。
专业词汇(天体物理)1、Galactic background γ-ray radiation 银河γ背景辐射2、active galactic nuclei 活动星系核3、radio survey 射电巡天4、ultraviolet fluxes 紫外流量5、Roche-lobe overflow 洛希瓣超流6、abnormal redshift 反常红移7、absorption cross section 吸收截面8、acceleration mechanism 加速机制9、general electric synchrotron 广义电同步加速10、screening effect 屏蔽效应11、visible spectrum 可见光谱12、celestial matter 宇宙物质13、broad emission-line 宽发射线14、narrow emission-line 窄发射线15、planetary nebulae 行星状星云16、isotropic antenna 各向同性天线17、Seyfert galaxy 赛弗特星系18、ultraviolet continuum 紫外连续谱19、bolometric luminosity 光度20、variable time scale 可变时标21、continuum emission 连续辐射22、power law 幂率23、non-thermal 非热24、blazar spectra blazar光谱25、polarization 偏振26、doppler broadened 多普勒展宽27、碰撞激发 collisional excitation28、photoionization 光致电离29、horizon of the universe 宇宙视界30、Coulomb collision 库仑碰撞31、Coulomb coupling 库仑耦合32、Born approximation 玻恩近似33、absolute magnitude 绝对星等34、absolute parallax 绝对视差35、overmassive object 超大质量天体36、gravitational wave 引力波37、gravitational-wave astronomy 引力波天文学38、error distribution 误差分布39、chromatic aberration 色差40、characteristic function 特征函数41、CGRO 康普顿γ射线天文台（Compton Gamma-Ray Observatory）42、central lobe 中心瓣43、Rayleigh criterion 瑞利判据44、Rayleigh limit 瑞利极限45、quasi-stellar object 类星体（QSO）46、quiescent radiation 宁静辐射47、quiescent spectrum 宁静光谱48、radial-velocity survey 视向速度巡天49、absorption frequency 吸收频率50、background radiation 背景辐射51、light illumination 光照度52、radiant power 辐射功率53、anisotropic medium 各向异性介质54、plasma jet instability 各向异性等离子体喷流不稳定性55、cosmic rays 宇宙线56、Zeeman effect 塞曼效应57、annihilation radiation 湮灭辐射58、radiometric magnitude 辐射星等59、proton flux 质子流量60、Abell cluster 阿贝尔星系团61、autocorrelation coefficient 自相关系数62、dark matter 暗物质63、Maxwellion distribution 麦克斯韦分布64、black hole binary 黑洞双星65、blanketing factor 覆盖因子66、radio galaxy 射电星系67、Cauchy's dispersion formula 柯西色散公式68、intergalactic medium 星系际介质69、shock wave 激波70、background Compton scattering 背景康普顿散射71、dark energy 暗能量72、multiple galaxy 多重星系73、current density 流密度74、thermodynamic equilibrium 热动平衡75、thermal excitation 热激发76、synchrotron radiation 同步加速辐射77、synchro-cyclotron radiation 同步-回旋加速辐射78、center of curvature 曲率中心79、super-relativistic effect 极端相对论性效应80、active binary 活动双星81、compact binary 致密双星82、compact galaxy nucleus 致密星系核83、supernova explosion 超新星爆发84、supernova ejecta 超新星喷射物85、deflection angle 偏转角86、cosmic noise absorption 宇宙噪声吸收87、string theory 宇宙弦理论88、stripped plasma 全电离等离子体89、close binary star 密近双星90、stellar-mass black hole 恒星质量黑洞91、ultraviolet radiation 紫外辐射92、aberration 光行差93、spontaneous emission 自发发射94、curvature radiation 曲率辐射95、spontaneous transition 自发跃迁96、peculiar spectrum 特殊光谱97、particle horizon 粒子视界98、stimulated radiation 受激辐射99、stimulated emission 受激发射100、circular polarization 圆偏振101、damping radiation 阻尼辐射102、spherical harmonics 球谐函数103、parity nonconservation 宇称不守恒104、drifting zebras 漂移带105、parallax second 秒差距（parsec) (pc）106、geometric aberration 几何象差107、electric multipole radiation 电多极辐射108、Voigt effect 佛克特效应109、monotonic model 单调宇宙模型110、isochronous correspondence 等时对应111、gas nebula 气体星云112、cepheid parallax 造父视差113、diffusion equation 扩散方程114、advancing shock front 前进激波前115、advection dominated accretion 径移吸积流116、spherical potential 球对称势117、luminous emittance 发光度118、cosmic gusher 宇宙喷射源119、microwave background 微波背景120、herpolhode 空间极迹121、heat of desorption 退吸热122、termination shock 终端激波123、very hard binary 甚硬双星124、weak turbulence theory 弱湍流理论125、nova-like X-ray source 类新星 X 射线源126、longitudinal chromatic aberration 纵向色差127、statistical equilibrium 统计平衡128、Compton cross-section 康普顿截面129、irregular nebula 不规则星云130、stellar astrophysics 恒星天体物理131、background radiation intensity 背景辐射强度132、optical binary 光学双星133、astronomical coordinate system 天文坐标系统134、orbital inclination 轨道倾角135、critical mass 临界质量136、Kerr-Newman black hole 克尔-纽曼黑洞137、Kerr-Newman metric 克尔-纽曼度规138、chromatism 色差139、reflection at critical angle 临界角反射140、source brightness distribution 源亮度分布141、Laplace's nebular hypothesis 拉普拉斯星云假说142、photoionized plasma 光电离等离子体143、photoluminescence 光致发光144、relaxation time 弛豫时间145、cross-correlation function 互相关函数146、relaxed cluster 驰豫星团147、disk-like structure 盘状结构148、fast-spinning black hole 快自旋黑洞149、Fermi Gamma-ray Space Telescope 费米γ射线空间望远镜150、time reversal 时间反演。
物理专业英语词汇(A)1/8 fluctuation 1/8 起伏1/f noise 1/f 噪声1/n expansion 1/n 展开3k cosmic blackbody radiation 3k 宇宙⿊体辐射4 counter 4 计数器a battery a电池组a posteriori probability 后验概率a priori probability 先验概率a15 structure a15 结构abbe coefficient 阿贝数abbe invariant 阿贝不变量abbe number 阿贝数abbe prism 阿贝棱镜abbe refractometer 阿贝折射计abbe sine condition 阿贝正弦条件abel theorem 阿贝尔定理abelian group 可换群abelian integral 阿贝尔积分aberage life 平均寿命aberration 象差aberration constant 光⾏差常数aberration of light 光⾏差aberrational ellipse 光⾏差椭圆ablation 烧蚀abm state abm 态abnormal 反常的abnormal cathode fall 反常阴极势降abnormal crystallization 异常晶化abnormal dispersion 异常⾊散abnormal glow 反常辉光放电abnormal grain growth 反常晶粒⽣长abnormal liquid 反常液体abnormal reflection 异常反射abnormal series 反常系abrasion 磨损abrasion test 磨损试验abrasives 研磨材料abrikosov's structure of flux lines 阿布⾥科蓑磁通线结构absence of gravity 失重absolute 绝对的absolute acceleration 绝对加速度absolute angular momentum 绝对⾓动量absolute atomic weight 原⼦的绝对重量absolute black body 绝对⿊体absolute configuration 绝对组态absolute counting 绝对计数absolute electrometer 绝对静电计absolute electrostatic system 绝对静电制absolute error 绝对误差absolute geopotential 绝对位势absolute humidity 绝对湿度absolute index of refraction 绝对折射率absolute instability 绝对不稳定性absolute magnitude 绝对星等absolute measurement 绝对测量absolute motion 绝对运动absolute ohm 绝对欧姆absolute orbit 绝对轨道absolute permeability 绝对磁导率absolute permittivity 绝对电容率absolute pressure 绝对压⼒absolute rest 绝对静⽌absolute rest frame 绝对静⽌系absolute rotation 绝对转动absolute scale 绝对度标absolute space 绝对空间absolute stability 绝对稳定absolute system of units 绝对单位制absolute temperature 绝对温度absolute temperature scale 绝对温标absolute thermometer 绝对温度表absolute time 绝对时空间absolute topography 绝对形势absolute unit 绝对单位absolute vacuum gage 绝对真空计absolute velocity 绝对速度absolute viscosity 绝对粘度absolute vorticity 绝对涡度absolute weight 绝对重量absolute zero 绝对零度absolute zero point 绝对零度absorb 吸收absorbed dose 吸收剂量absorbent 吸收剂absorber 吸收体absorbing medium 吸收媒质absorptiometer 吸收计absorption 吸收absorption band 吸收带absorption coefficient 吸收系数absorption cross section 吸收截⾯absorption curve 吸收曲线absorption edge 吸收端absorption equilibrium 吸收平衡absorption factor 吸收因⼦absorption filter 吸收滤光器absorption hygrometer 吸收湿度表absorption index 吸收指数absorption jump 吸收跃迁absorption limit 吸收端absorption line 吸收线absorption method 吸收法absorption model 吸收模型absorption of sound 声的吸收absorption spectrometer 吸收光谱仪absorption spectroscopy 吸收光谱学absorption spectrum 吸收光谱absorption test 吸收试验absorptive 吸收的absorptive power 吸收本领absorptivity 吸收本领abstract algebra 抽象代数abstract group 抽象群abstract space 抽象空间abstraction 抽象abundance of elements 元素的丰度ac bias 交莲压ac circuit 交羚路ac galvanometer 交羚疗ac voltage 交羚压accelerated motion 加速运动accelerating chamber 加速室accelerating electrode 加速电极accelerating field 加速场accelerating gap 加速隙缝accelerating period 加速周期accelerating slit 加速隙缝accelerating tube 加速管accelerating voltage 加速电压acceleration 加速度acceleration cavity 加速共振腔acceleration gap 加速隙acceleration of gravity 重⼒加速度accelerator 加速器accelerometer 加速计acceptance 肯定acceptor 受主acceptor center 受中⼼acceptor impurity 受钟质acceptor level 受周级access 选取access speed 选取速度access time 选取时间accessibility 可达性accessible point 可达点accessories 附件accidental coincidence 偶然符合accidental degeneracy 偶然退化accidental error 偶然误差accidental reflection 偶然反射acclimation ⽓候驯化acclimatization ⽓候驯化acclimazation ⽓候驯化accommodation 第accommodation coefficient 适应系数accommodation of the eye 眼的第accord 和⾳accreting black hole model 吸积⿊洞模型accretion 吸积accretion disk 吸积盘accumulated dose 累积剂量accumulated error 累积误差accumulated temperature 积温accumulation 蓄集accumulation layer 累积层accumulation point 聚点accumulation ring 累积环accumulator ⼆次电池accuracy 准确度accuracy grade 准确度accuracy of measurement 测量精确度accuracy of readings 读数准确度accuracy rating 准确度acetone 丙酮achondrite ⽆球粒陨⽯achromat 消⾊差透镜achromatic 消⾊的achromatic color ⽆彩⾊achromatic condition 消⾊差achromatic lens 消⾊差透镜achromatic prism 消⾊差棱镜achromatic quarter wave prism 四分之⼀波长消⾊棱镜achromatic sensation ⽆⾊感觉achromatic stimulus ⽆⾊剌激achromatism 消⾊差acid 酸acnod 孤点acoumeter 测听计acount 计算acoustic 声的acoustic absorption coefficient 吸声系数acoustic absorptivity 吸声系数acoustic admittance 声导纳acoustic analysis 声分析acoustic conductivity 声导率acoustic diffraction 声衍射acoustic dispersion 声弥散acoustic disturbance 声扰动acoustic electron spin resonance 声电⼦⾃旋共振acoustic emission 声发射acoustic far field 远程声场acoustic field 声场acoustic filter 滤声器acoustic fraunhofer field 夫琅和费声场acoustic frequency ⾳频acoustic fresnel field ⾮涅⽿声场acoustic gravity wave 声⼒波acoustic image 声象acoustic impedance 声阻抗acoustic instrument 声学仪器acoustic interferometer 声波⼲涉计acoustic lens 声透镜acoustic line 声传输线acoustic load 声负载acoustic material 吸⾳材料acoustic measurement 声学量度acoustic microscope 超声显微镜acoustic mode 声学模acoustic near field 近程声场acoustic nuclear magnetic resonance 声核磁共振acoustic ohm 声欧姆acoustic paramagnetic resonance 声顺磁共振acoustic power 声功率acoustic pressure 声压acoustic radiator 声辐射体acoustic reactance 声抗acoustic resistance 声阻acoustic resonance 声共振acoustic resonator 声共振器acoustic shadow 声影acoustic signal 声信号acoustic sounding 声学探测acoustic streaming 声风acoustic transducer 声能转换器acoustic transformer 声变换器acoustic velocity 声速acoustic wave 声波acoustic wind 声风acoustical 声的acoustical holography 声全息学acoustical spectroscopy 声谱学acoustically induced birefringence 声诱发双折射acoustics 声学acoustimeter 声强计acoustodynamic 声动⼒学的acoustoelectric amplification 声电放⼤acoustoelectric effect 声电效应acoustoelectron interaction 声电⼦相互酌acoustoelectronics 声电⼦学acoustomagnetoelectric effect 声磁电效应acoustooptic effect 光声效应acoustooptical 声光的acoustooptical modulator 声光灯器acoustooptical q switch 声光 q 开关acoustooptical radiospectrometer 声光射电光谱仪acoustooptics 声光学acre 英亩acrobatic metal 特技的⾦属acryl resin 丙烯酸⼫actinic 有光化性的actinic photometer 光化光度计actinic rays 光化射线actinic value of light 光化度actinides 锕系actinism 光化酌actinium 锕actinium emanation 锕射⽓actinium series 锕系actinograph ⽇射仪actinoid nuclei 锕系元素核actinometer ⽇射表actinometry 辐射测量;光能强度测定actinomorphy 辐射对称性actinon 锕射⽓action 酌action at a distance 超距酌action centre of the atmosphere ⼤⽓活动中⼼action integral 酌积分action principle 酌原理action spectrum 酌谱action through medium 媒递酌action variable 酌变量activated 激化了的activated adsorption 活性吸附activated atom 激活原⼦activated molecule 激活分⼦activating agent 活化剂activation 活化activation analysis 放射化分析activation cross section 放射化截⾯activation energy 激活能activation method 激活法activator 活化剂active 活性的active carbon 活性炭active current 有效电流active front 活跃锋active galactic nucleus 活动星系核active galaxy 活动星系active hydrogen 活性氢active laser element 激活激光元件active laser spectroscopy 活性激光光谱学active laser substance 激活物质active lattice 放射性栅格active locking 受迫模同步active material 放射材料active network 有源络active oxygen 活性氧active power 有效功率active product 放射性产物active prominence 活动⽇珥active q switching 激活 q 开关active sun 活动太阳active volcano 活⽕⼭activity 放射性activity coefficient 活度系数activity unit 放射性单位actual 真实的actual load 有效的acumulative temperature 积温acute 尖锐acute angle 锐⾓acute angled 锐⾓的acute angled triangle 锐⾓三⾓形acute triangle 锐⾓三⾓形acuteness 锐度acyclic ⾮循环的ada ada 语⾔adamantine luster ⾦刚光泽adaptability 适应性adaptation 适应adaptive antenna ⾃适应天线adaptive optics ⾃适应光学adaptometer 适应测量计adatom 吸附原⼦add 加add circuit 加法电路addend 加数adder 加法器adding element 求和器addition 加法additional 加法的additional code 补码additional heating 附加加热additional mass 附加质量additive 加法的additive group 加法群additive method 加⾊法additive property 加和性additive theory of numbers 加性数论additivity 加和性address 地址address part 地址部分address register 地址寄存器adenosine triphosphate 三磷酸腺苷adequate 适合的adhere 粘着adherence 附着adhesion 附着adhesive force 附着⼒adhesives 粘接剂adiabat 绝热线adiabatic 绝热的adiabatic approximation 绝热近似adiabatic atmosphere 绝热⼤⽓adiabatic calorimeter 绝热式量热器adiabatic change 绝热变化adiabatic compression 绝热压缩adiabatic cooling 绝热冷却adiabatic curve 绝热线adiabatic demagnetization 绝热退磁adiabatic equilibrium 绝热平衡adiabatic expansion 绝热膨胀adiabatic exponent 绝热指数adiabatic free expansion 绝热⾃由膨胀adiabatic heating 绝热增温adiabatic hypothesis 绝热假说adiabatic index 绝热指数adiabatic invariant 绝热不变量adiabatic lapse rate 绝热温度梯度adiabatic magnetic susceptibility 绝热磁化率adiabatic nuclear demagnetization 绝热核去磁adiabatic potential curve 绝热势能曲线adiabatic potential surface 绝热位势⾯adiabatic principle 浸渐原理adiabatic process 绝热过程adiabatic pulsations 绝热脉动adiabatic temperature gradient 绝热温度梯度adiabatic theorem 绝热定理adiabaticity 绝热性adiabatics 绝热线adjacent angles 邻⾓adjacent side 邻边adjoint differential equation 伴随微分⽅程adjoint operator 伴随算符adjoint system 伴随系adjunct 代数余⼦式adjunction 附加adjustable point 可定点adjustment 蝶admissible 容许的admissible error 容许误差admissible value 容许值admittance 导纳admittance matrix 导纳矩阵adsorb 吸附adsorbate 吸附物adsorbed atom 吸附原⼦adsorbent 吸附剂adsorption 吸附adsorption capacity 吸附本领adsorption isotherm 等温吸附式adsorption structure 吸附结构advance of periastron 拱线运动advanced potential 超前势advancing wave 前进波advection 平流平移advection fog 平另advective 平聊aeolian tone 风吹声aerial 空⽓的aerial survey 航空测量aeroacoustics 空⽓声学aerobiology ⾼空⽣物学aeroclimatology ⾼空⽓候学aerodone 滑翔机aerodynamic balance 空⽓动⼒天秤aerodynamic drag 空⽓阻⼒aerodynamic focus ⽓动⼒学焦点aerodynamic heating ⽓动⼒加热aerodynamic lift ⽓动升⼒aerodynamic resistance 空⽓阻⼒aerodynamics 空⽓动⼒学aerogel ⽓凝胶aerohypsometer 航空测⾼计aerolite ⽯陨星aerological ⾼空⽓象学的aerological diagram ⾼空图解aerology ⾼空⽓象学aeromagnetics 航空磁学aeromechanics 空⽓⼒学aerometer ⽓体⽐重计aeronautical 航空的aeronautical meteorological observation 航空⽓象观测aeronautical meteorological station 航空⽓象站aeronautical meteorology 航空⽓象学aeronautics 航空学aeronomy ⾼层⼤⽓物理aerophysics 航空物理学aeroplane 飞机aeroport 航空航aerosol ⽓溶胶aerospace science 空间航空科学aerostatics ⽓体静⼒学affine 仿射的affine coordinates 仿射坐标affine geometry 仿射⼏何affine space 仿射空间affine transformation 仿射变换affinity 亲合势affirmation 肯定affix 标出afocal ⾮焦点的after discharge 后续放电after heat 残热afterglow 余辉afterimage 残留影象aftershock 余震age 陈化age determination 测定年代age equation 年龄⽅程age hardening 时效硬化age of the moon ⽉龄age theory 年龄理论ageostrophic wind ⾮地转风aggregate 聚合体aggregation 聚集aging 时效agonic line ⽆偏线agreement ⼀致agricultural climatology 农业⽓候学agricultural meteorology 农业⽓象学agroclimatology 农业⽓候学agrometeorology 农业⽓象学agrophysics 农业物理学aharonov bohm effect 阿哈拉诺夫玻姆效应air capacitor 空⽓电容器air cell 空⽓电池air chamber ⽓室air 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关于星云的浪漫句子英文1. The stars in the night sky are like tiny specks of stardust, sprinkled across the Nebulas, creating a galaxy of romance.2. The shimmering cosmic dust of the Orion constellation reminds me of your sparkling eyes, filled with love and wonder.3. As I gaze at the Milky Way, I am reminded of the ethereal beauty of our love, stretching across the endless expanse of space and time.4. Lost in the vastness of the universe, my heart finds solace in the twinkling of the stars, knowing that our love is as infinite as their light.5. The celestial dance of the planets and the stars mirrors the graceful way you move, captivating my heart with every step.6. Like a shooting star, our love streaks across the night sky, leaving behind trails of dreams and hope.7. The constellations align, creating a celestial map that guides me to your heart, my one true love.8. Just as the moon reflects the sun's brilliance, your love reflects and illuminates the deepest corners of my soul.9. The interstellar dust fills the void, just as your love fills the emptiness in my heart.10. The cosmic energy that binds the universe is akin to the deep connection that binds our souls together.11. Your voice is like a celestial melody, resonating with the harmony ofthe stars.12. Whenever I see a shooting star, I make a wish for our love to forever burn bright, just as they do.13. Lying on the grass, staring at the night sky, I feel like I am floating in a sea of stars, carried away by the magic of your love.14. Every time I see the Big Dipper, I am reminded of how you fill my life with love and laughter.15. Your love is like a black hole, pulling me in with its gravitational force, but unlike a black hole, it fills my life with light.16. Just like the ever-expanding universe, my love for you knows no bounds.17. Each unique star in the night sky represents a moment of our love story, frozen in time, illuminating the darkness.18. The celestial bodies in the night sky seem scattered, but they all have an invisible connection, just like our hearts.19. Our love is like a newly discovered star, shining brightly against the backdrop of the universe, capturing the attention of all who gaze upon it.20. The beauty of the night sky pales in comparison to the radiance of your smile.21. The stars are the brightest when you're by my side, as if they want to witness our love story unfold.22. Our love is like a meteor shower, showering the world with sparks ofjoy and wonder.23. The vastness of the universe seems insignificant when compared to the depth and magnitude of our love.24. The interstellar dust whispers secrets of the universe, and I am reminded of the secrets we share, known only to us.25. The beauty of the stars cannot be fully captured by words, just as the beauty of our love cannot be fully expressed.。
a rXiv:076.3938v1[astro-ph]26J un27Submitted for publication in the Special GALEX Ap.J.Suppl.Issue The UV-Optical Galaxy Color-Magnitude Diagram I:Basic Properties Ted K.Wyder 1,2,D.Christopher Martin 1,David Schiminovich 3,Mark Seibert 4,Tam´a s Budav´a ri 5,Marie A.Treyer 1,6,Tom A.Barlow 1,Karl Forster 1,Peter G.Friedman 1,Patrick Morrissey 1,Susan G.Neff7,Todd Small 1,Luciana Bianchi 5,Jos´e Donas 6,Timothy M.Heckman 8,Young-Wook Lee 9,Barry F.Madore 4,Bruno Milliard 6,R.Michael Rich 10,Alex S.Szalay 8,Barry Y.Welsh 11,Sukyoung K.Yi 9ABSTRACT We have analyzed the bivariate distribution of galaxies as a function of ultraviolet-optical colors and absolute magnitudes in the local universe.The sample consists of galaxies with redshifts and optical photometry from the Sloan Digital Sky Survey (SDSS)main galaxy sample matched with detections in the near-ultraviolet (NUV )and far-ultraviolet (F UV )bands in the Medium Imaging Survey being carried out by the Galaxy Evolution Explorer (GALEX)satellite.In the (NUV −r )0.1vs.M r,0.1galaxy color-magnitude diagram,the galaxiesseparate into two well-defined blue and red sequences.The(NUV−r)0.1colordistribution at each M r,0.1is not wellfit by the sum of two Gaussians due to anexcess of galaxies in between the two sequences.The peaks of both sequencesbecome redder with increasing luminosity with a distinct blue peak visible up toM r,0.1∼−23.The r0.1-band luminosity functions vary systematically with color,with the faint end slope and characteristic luminosity gradually increasing withcolor.After correcting for attenuation due to dust,wefind that approximatelyone quarter of the color variation along the blue sequence is due to dust with theremainder due to star formation history and metallicity.Finally,we present thedistribution of galaxies as a function of specific star formation rate and stellarmass.The specific star formation rates imply that galaxies along the blue se-quence progress from low mass galaxies with star formation rates that increasesomewhat with time to more massive galaxies with a more or less constant starformation rate.Above a stellar mass of∼1010.5M⊙,galaxies with low ratios ofcurrent to past averaged star formation rate begin to dominate.Subject headings:galaxies:evolution—galaxies:fundamental parameters—galaxies:luminosity function—galaxies:statistics—galaxies:surveys—ul-traviolet:galaxies1.IntroductionGalaxies exhibit bimodal distributions in a number of observed properties.The bimodal-ity in galaxy morphologies formed the basis of the original galaxy classification scheme of Hubble(1926).The colors and luminosities of galaxies have been long known to correlate with morphology(e.g.de Vaucouleurs1961;Chester&Roberts1964)with ellipticals being predominantly red and spirals and irregulars blue.More recently,large statistical samples of galaxies have become available,allowing us to investigate the bimodality of galaxies in a much more quantitative way.In particular, the bimodality appears quite strongly in the galaxy(u−r)color distribution which con-sists of two peaks with a minimum in between them at(u−r)≈2.1−2.2(Strateva et al. 2001).Galaxies in the red peak tend to be predominantly morphologically early-type and high surface brightness galaxies while those in the blue peak are dominated by morpho-logically late-type galaxies with lower surface brightness(Strateva et al.2001;Driver et al. 2006;Blanton et al.2003b;Ball et al.2006).Based upon a sample of low-redshift galaxies from the SDSS,Baldry et al.(2004)investigated the distribution of galaxies in the(u−r) vs.M r color-magnitude diagram(CMD).The galaxies in their sample separate into blueand red sequences with the distribution in color at each absolute magnitude well-fit by the sum of two Gaussians.The mean color as a function of M r for each sequence consists of an overall reddening with increasing luminosity with a steeper transition in the average color and width of both sequences at a stellar mass of∼2×1010M⊙.In addition to mass,one of the most important other factors suspected of contributing to the galaxy bimodality is the environment.While it has long been known that the mor-phologies of galaxies are correlated with the local density(Dressler1980),the dependence of galaxy colors and luminosities with local density is complicated.Although the ratio of the number of red to blue galaxies varies strongly with the local density,the mean color of the blue and red sequences varies relatively little with environment(Balogh et al.2004). On the other hand,the luminosity of blue sequence galaxies is nearly independent of envi-ronment while both luminous and faint red galaxies are found on average in higher density environments than intermediate luminosity red galaxies(Hogg et al.2003).The galaxy bimodality has also begun to be investigated based upon large samples of galaxy spectra from the Sloan Digital Sky Survey(SDSS).In particular,Kauffmann et al. (2003a)developed a method that uses the Balmer absorption line index HδA and the4000˚A break strength D n(4000)measured from the SDSSfiber spectra in the central3′′of each galaxy to constrain the star formation histories,dust attenuation,and stellar masses for their sample.Based upon these derived parameters,Kauffmann et al.(2003b)showed that galaxies tend to divide into two distinct groups around a stellar mass of3×1010M⊙, similar to the transition mass noted in the optical galaxy CMD(Baldry et al.2004).While galaxies below this mass tend to have younger stellar populations,more massive galaxies tend to be older.In related work,Brinchmann et al.(2004)used the emission lines in the SDSS spectra to determine star formation rates(SFRs)for a large sample of SDSS ing the specific star formation rate,i.e.the current SFR divided by the stellar mass M∗,Brinchmann et al.(2004)found that galaxies with108<M<109M⊙have log(SF R/M∗)=−9.6to−10,values consistent with an approximately constant SFR with time.Above1010M⊙,the specific SFRs decline with mass,implying star formation histories increasingly weighted to much older ages.The evolution of the galaxy color-magnitude diagram out to z∼1has begun to be explored(Willmer et al.2006;Faber et al.2006;Blanton2006).These results show that the galaxy bimodality is already in place at z∼1.However,the color of both sequences tends to become somewhat bluer with increasing redshift while the luminosity function of both red and blue galaxies shifts to higher luminosities(Blanton2006;Willmer et al.2006). Based upon combining the DEEP2and COMBO17surveys,Faber et al.(2006)argued that the number density of blue galaxies is more or less constant from z∼1to z∼0,while thenumber density of red galaxies has been increasing.Faber et al.(2006)proposed a scenarioto explain their data in which some blue galaxies migrate to the red sequence as a result of gas-rich mergers that use up the remaining gas in an interaction-induced starburst.These galaxies then migrate up the red sequence by a series of gas-free mergers.The origin of the galaxy bimodality and corresponding transition mass of a few×1010M⊙is beginning to be understood theoretically.Based upon a semi-analytic model utilizing some simple prescriptions for gas cooling,star formation,and supernova feedback coupled with merging histories of dark matter haloes,Menci et al.(2005)modeled the(u−r)vs.M r CMD of Baldry et al.(2004).In their model,feedback from supernovae is ineffectiveat regulating star formation for galaxies above a certain threshold halo mass.In these massive galaxies all of the gas is consumed relatively quickly and results in a red sequence galaxy at zero redshift.Blue sequence galaxies,on the other hand,tend to come from less massive progenitors where supernovae feedback is effective at regulating star formation,thus allowing star formation to continue down to the present.While their model is successfulat reproducing most of the optical CMD,it predicts too many blue galaxies at M r=−22 compared to the observations.A different explanation for the origin of bimodality has been suggested by Dekel&Birnboim (2006).According to this model,above a critical halo mass M shock∼1012M⊙,a shock is generated in the gas accreting onto the dark matter halo which heats most of the gas and prevents it from cooling and forming stars.In these massive haloes,star formation does happen at z 2due to cold gas that is able to penetrate the hot gas,leading to a burst of star formation,while for z 2heating from Active Galactic Nuclei(AGN)prevents gas from forming any more stars.This naturally leads to the most massive galaxies lying on the red sequence at z∼0.For galaxies residing in halos with masses less than1012M⊙,the gas is not shock heated,allowing coldflows to fuel star formation that is then regulated by supernova feedback.As a result,lower mass galaxies lie on the blue sequence and the location of the bright tip of the blue sequence is due to the onset of the shock in the accreting gas for more massive halos and the feedback from AGN.In this scenario,galaxies tend to move up the blue sequence with time until their masses go above M shock,or they merge into another more massive halo with mass above M shock,after which the gas in the galaxy is no longer allowedto cool and star formation ceases.Both Cattaneo et al.(2006)and Croton et al.(2006)have coupled semi-analytic models including the transition from shock heating to coldflows and feedback from supernova as well as AGN with the merging histories of dark matter haloes from N-body simulations.While the details of the modeling of the baryonic physics differs somewhat,both groups were able to reproduce the local galaxy CMD by tuning the various parameters affecting star formation and feedback in their models.In this paper,we investigate the galaxy bimodality as revealed in the UV minus optical colors of a large sample of galaxies observed by both the Galaxy Evolution Explorer(GALEX) and the SDSS.While significant contributions to the UV luminosity can come from older evolved stars in red sequence galaxies(e.g.Yi et al.2005;Rich et al.2005),in general the UV light in galaxies is dominated by massive stars with main sequence lifetimes up to∼108 yrs.As a result,the emerging UV luminosity is proportional to the recent star formation rate once corrected for light absorbed by dust(Kennicutt1998).The greater sensitivity of the GALEX bands to the recent star formation rate as compared to the SDSS u band would lead us to expect a greater separation between the red and blue sequences.While the measurements from the SDSS spectra are sensitive diagnostics of the stellar populations in galaxies,they are measured only in the central3′′of each galaxy,making somewhat uncertain aperture corrections necessary to account for the portion of each galaxy not sampled.While the UV data presented here is much more susceptible to dust attenuation than in the optical SDSS data,the UV measurements sample the entire galaxy and thus complement the SDSS measurements.2.Data and Analysis2.1.GALEX DataThe UV data presented here are derived from the GALEX Medium Imaging Survey (MIS)(Martin et al.2005).GALEX is a50cm diameter UV telescope that images the sky simultaneously in both a F UV and a NUV band,centered at1540˚A and2300˚A, respectively.Thefield-of-view of GALEX is approximately circular with a diameter of1.◦2 and resolution of about5.′′5FWHM in the NUV.The MIS pointings are chosen to overlap areas of sky with imaging and spectroscopy from the SDSS and consist of exposures of at least one to a few orbits with the mode of the exposure time distribution being1700sec. The dataset used in our analysis is taken from the union of the GALEXfirst data release (GR1)with the GALEX internal release IR1.1,a subset of which has been included in the second data release(GR2)publicly available from the GALEX archive.1The IR1.1data was processed with a pipeline very similar to that used in the GR1data and employed the same calibration as used in that release.Details of the GALEX detectors,pipeline,calibration and source extraction can be found in Morrissey et al.(2005,2007).The GALEX pipeline uses the SExtractor program(Bertin&Arnouts1996)to de-tect and make measurements of sources in the images.Throughout this paper,we use the”MAGAUTO aperture and theflatfield response,exposure time,and sky background at the source position.In addition to the sta-tistical errors,we have added in quadrature an assumed zero-point plusflatfield uncertainty of2%in the NUV and5%in the F UV(Morrissey et al.2007).The errors increase from the zeropoint uncertainty at the bright end up to≈0.2−0.3mag at23rd mag in both bands.2.2.GALEX-SDSS Matched SampleThe GALEX MIS catalogs were matched with the SDSS MPA/JHU DR4value-added catalogs.2These catalogs consist of line and index measurements from the SDSS spectra as well as many derived quantities and are described in more detail in a series of papers on the star formation rates,star formation histories,stellar masses,and metallicities of galaxies in the local universe(Kauffmann et al.2003a,b;Brinchmann et al.2004;Tremonti et al.2004). For each GALEX pointing,SDSS sources within0.◦6of the GALEXfield center were matched with the nearest GALEX source within a radius of4′′.When concatenating together the catalogs for all thefields,we removed duplicate GALEX detections in the overlap regions between adjacent pointings by using the SDSS identification numbers(Plate ID,MJD,Fiber ID)and selecting the GALEX match closest to itsfield center.After matching the GALEX and SDSS data,we further restricted the sample with various cuts intended to generate a complete statistical sample which are summarized in Table1.For the SDSS photometry,we selected galaxies targetted for spectroscopy in the SDSS main galaxy sample with r-band magnitudes in the range14.5<r<17.6.While the nominal magnitude limit of the SDSS main galaxy sample is r=17.77(Strauss et al.2002), in practice the limit varies as a function of position on the sky.After examining the galaxy number counts,we set the faint limit to r=17.6because the counts begin to turn-over below this level.While the median photometric error for the SDSS galaxies is only0.03mag,there are a small fraction with much larger errors.In order to remove these objects,we restrictedthe sample to galaxies with errorsσr<0.2mag.In addition to the photometry,we further restricted the sample to those galaxies with redshifts z in the range0.01<z<0.25and with redshift confidence z conf>0.67.In addition to the cuts on the SDSS data,we applied several cuts based upon the UV measurements.Since GALEX photometry and astrometry degrade near the edge of the detectors,we only included objects in the sample if their distance from the GALEX field center fovartifact≤1.This excludes from our sample galaxies that lie within regions expected to be contaminated by reflections from bright stars within thefield.Areas of the images with nuvIn the F UV sample,the red edge of the color distribution thus reflects the UV magnitude limit.The fraction of SDSS main sample galaxies that lie within0.◦55of a GALEX MISfield center and that have a GALEX match within our4′′search radius is shown in Figure4as a function of r magnitude.In the NUV sample,the completeness is roughly constant at about90%down to r≈16.5.Fainter than this magnitude,the completeness begins to drop off.There are very few galaxies with colors redder than(NUV−r)≈6.5.At the GALEX magnitude limit of23mag,a galaxy with this red a color would have r=16.5.Thus,the fraction of SDSS galaxies with a GALEX match begins to drop fainter than this r magnitude due to increasing numbers of red galaxies falling below the GALEX detection limit.For the F UV sample,the reddest galaxies have(F UV−r)≈7.5which corresponds to r=15.5at the limiting magnitude of F UV=23.As expected,the fraction of SDSS galaxies with an F UV match begins to decline at about this r magnitude.In both the F UV and NUV samples,the match completeness does not reach100% at bright r magnitudes.We have visually inspected all SDSS main sample galaxies with14.5<r<15.5that were observed by GALEX.For almost all of these galaxies,there isa galaxy visible in the GALEX images.However,the UV center measured by the GALEX pipeline for these non-matches lies more than4′′from the SDSS position.Sometimes the GALEX pipeline breaks the galaxy into more than one fragment,none of which are coincident with the SDSS position.In other cases,especially if the galaxy has a low UV surface brightness,the center can be offset from the SDSS position by more than our search radius even if the GALEX pipeline detects the galaxy as a single object.We assume that the level portion of the match completeness curves in Figure4gives the intrinsic completeness for GALEX detections of the SDSS main galaxy sample.The values we adopt are0.91and0.80 for the NUV and F UV,respectively.While the completeness of the SDSS photometric sample is nearly100%,some fraction of galaxies that meet the SDSS main galaxy sample selection do not have a redshift measured (Strauss et al.2002).Although some galaxies do not have a redshift due to low signal-to-noise in their spectra,the majority of targeted galaxies without redshifts are missed due to the constraint that SDSS spectroscopyfibers can not be placed closer than55′′to one another.Some of these missed galaxies can be observed in neighboring plates if that region of sky is covered by more than one plate.While the exact completeness is determined by the precise geometry of the spectroscopic plates,the result is that the spectroscopic completeness of the SDSS main galaxy sample is92-94%for the early release data(Strauss et al.2002; Blanton et al.2001).We have adopted a spectroscopic completeness of0.9.Multiplying the GALEX-SDSS match completeness by the SDSS spectroscopic completeness,we estimatedthe total completeness of our sample to be0.82in the NUV and0.72in the F UV.In calculating the volume densities below,we correct the number counts by these factors,(i.e. the factor f in equations(5)and(6)below).In addition to the spectroscopic incompleteness,there is an additional surface brightness selection that is imposed on the SDSS main galaxy sample.As a part of their study of the luminosity function of low luminosity galaxies,Blanton et al.(2005)investigated the com-pleteness as a function of surface brightness and found that the SDSS spectroscopic galaxy sample is greater than90%complete above a half light surface brightness ofµ50,r=22.4 mag arcsec−2with the completeness dropping to50%atµ50,r=23.4mag arcsec−2.Since lu-minosity and surface brightness are correlated,the surface brightness selection preferentially selects against dwarf galaxies.For galaxies brighter than M r=−18,Blanton et al.(2005) have afit a gaussian to the surface brightness distribution in a series of absolute magnitude bins and have used this model to extrapolate the number of galaxies likely missed due to the surface brightness selection at fainter luminosities.The fraction of galaxies missing from the sample increases from near zero at M r=−18to approximately40%at M r=−16.However, these low luminosity,low surface brightness galaxies do not make a significant contribution to the total luminosity density.Even after correcting for the surface brightness incomplete-ness,about90%of the r-band luminosity density is due to galaxies with M r<−17.Thus, the surface brightness selection is unlikely to affect our results for bright galaxies.However, we may be underestimating the number density of galaxies with−18<M r<−16by up to 40%.2.3.Absolute magnitudes and volume densitiesWe computed absolute magnitudes for our sample galaxies using,for example for the r-band,M r,0.1=m r−5log D L−25−K0.1,r(z)+(z−0.1)Q(1) where M r,0.1is the absolute magnitude,m r is the extinction corrected r-band magnitude, D L is the luminosity distance in Mpc,K0.1,r(z)is the K-correction needed to account for the shifting of the galaxy SEDs with respect to thefilter bandpass,and Q is a term to account for luminosity evolution in units of magnitudes per redshift.A positive value for Q means that galaxies get brighter with increasing redshift.Similar equations were used for the other bands.For calculating the luminosity distance we assumed a Hubble constant H0=70km s−1Mpc−1and aflat universe with matter density relative to the critical density ofΩm=0.3and dark energy density ofΩΛ=0.7.We calculated the K-corrections using the Know extended to handle GALEX data(Blanton&Roweis2007).Given the redshift of a galaxy,the Kwhile that of red galaxies is increasing.In order to asses the effect of color evolution on our results,we have recomputed the absolute magnitudes and volume densities described below for the NUV sample assuming evolution in the r-band of Q r=1.6and in the NUV of Q NUV=3.These choices correspond to a decrease in the(NUV−r)color of a galaxy across our redshift range from0.01<z<0.25 of0.34mag.We have compared many of the results presented in the following sections with and without allowing for color evolution.The morphology of the color-magnitude diagram remains largely unchanged with the peaks and widths of the red and blue sequences nearly the same.The largest effect of including color evolution is on the volume density of luminous blue galaxies since these galaxies are detectable across the entire redshift range and thus would have the largest color correction.Including color evolution also tends to increase somewhat the volume density of galaxies with very blue colors(NUV−r)<1.Specifically, including color evolution would increase the luminosity density of the bluest galaxies with 0<(NUV−r)<1by0.2dex in the r-band and by0.3dex in the NUV.Due to the large uncertainties remaining in the evolution of galaxy colors with redshift and the relatively minor effect it has on our results,we decided to neglect color evolution in our analysis.When correcting for Galactic extinction,we assumed the Cardelli et al.(1989)extinction law with R V=A V/E(B−V)=3.1.For the SDSS bands,the ratio of A(λ)/E(B−V)is 5.155,3.793,and2.751for u,g,and r,respectively,while for the F UV the ratio is8.24. Due to the presence of the2175˚A bump in the Galactic extinction law,the extinction in the NUV band is no longer strictly proportional to the reddening E(B−V).In order to quantify the effect this has on our extinction corrections,we used a small set of42 SEDs from Bruzual&Charlot(2003)that span a representative range of galaxy SEDs from quiescent ellipticals to rapidly star-forming galaxies.3For each intrinsic SED,we applied the Cardelli et al.(1989)extinction law and then computed the resulting NUV AB magnitude as a function of E(B−V).For each SED,wefit a a quadratic function of E(B−V):A NUV=a1E(B−V)+a2E(B−V)2.(2) For galaxies with some recent star formation,a1=8.24and a2=−0.67while for older galaxies with little or no recent star formation and a SED that falls steeply in the UV with decreasing wavelength,a1is slightly smaller and lies in the range7.5−8.0.For97%of our sample E(B−V)<0.1,and thus the quadratic term can be safely neglected.In addition, the maximum difference in the adopted value for A(NUV)for the range of values for a1 among the42SEDs,is only0.07mag at E(B−V)=0.1.Therefore,we assume the value A(NUV)/E(B−V)=8.2for all of our calculations.PHARE.html.As argued above,the fraction of SDSS main sample galaxies with GALEX detections is a strong function of the galaxy color.In Figures5and6,we plot contours of the fraction of SDSS galaxies with a GALEX match for the NUV and F UV samples,respectively.In both samples,the completeness for blue galaxies is more than90%while the completeness begins to drop for galaxies with(g−r)0.1>0.8.For the NUV sample the completeness along most of the red sequence is in the range30−60%while the completeness of the red sequence in the F UV sample is lower and in the range10−40%.It is important to note that this drop-offin the fraction of galaxies with a GALEX match is due to the GALEX magnitude limit and was taken into account below when computing the volume densities of galaxies as a function of absolute magnitude and color.We used the V max method(Schmidt1968)to determine the volume densities of galaxies in our samples.The value of V max for each galaxy is given by the maximum volume within which the galaxy could have been included in the sample,given our selection limits listed in Table1.We computed a separate V max for the F UV and NUV samples.First,we computed K0.1(z)for0.01<z<0.25for each galaxy using the best-fit SED derived from the output of the K3 π(1+z max)3−D L(z min)3∆M∆C 1that particular color and absolute magnitude bin centered on M r,0.1and(NUV−r)0.1.The corresponding uncertainty in each bin due to counting statistics is given byδΦ(M r,0.1,(NUV−r)0.1)=fV2max 1/2.(6)3.Results3.1.The Galaxy Color Magnitude DiagramThe number of galaxies in our(NUV−r)0.1and(F UV−r)0.1CMDs are plotted in Figures7and8,respectively.In both plots,the data are plotted as contours where the density of points is high while the locations of individual galaxies are plotted where the density is low.The uncertainty in the colors in both samples is dominated by the errors in the UV measurements.Thus the errors as a function of position in the CMDs are most strongly correlated with color.The median error as a function of color is plotted in Figures7 and8along the left-hand side of eachfigure.For blue galaxies,the uncertainty is dominated by the zero-point uncertainty in the GALEX data.For red galaxies,the errors span a larger range from0.1−0.4mag with a median of about0.2mag.The corresponding volume densities of galaxies as a function of position in the CMD are plotted in Figures9and10,where the weighting was derived from the V max values as in equation(5)with∆M=0.5mag and∆C=0.2mag.The peak of each sequence from the Gaussianfits described below are over-plotted as the dashed lines in the(NUV−r)diagram. The volume densities and the errors for the(NUV−r)diagram are given in Tables2and 3while those for the(F UV−r)diagram are given in Tables4and5.As we have argued in§2.2,the red edge of the color distribution in the NUV sample is real whereas the red edge of the F UV sample is a selection effect due to the F UVflux limit.This is reflected in the morphology of the galaxy distributions in Figures9and10, where the distribution turns over for the reddest colors in the NUV diagram and does not turn over entirely in the F UV diagram.Throughout the remainder of this paper,we focus on the NUV diagram.In both the F UV and NUV diagrams,the galaxies separate into two well-defined se-quences in addition to a population of galaxies that lie in between.As has been noted before in optical CMDs(e.g.Baldry et al.2004),the most luminous galaxies are on the red sequence,while both sequences become redder with increasing luminosity.In contrast to the optical(u−r)CMD,the blue sequence does not appear to merge at the bright end with the red sequence.An alternative view of the NUV sample is shown in Figure11where the volume density of galaxies is plotted as a function of the NUV luminosity.The sample reaches significantly fainter NUV absolute magnitudes for the red galaxies due to the SDSS r-band selection. Thus,the slope for the faintest NUV absolute magnitudes included in our sample as a function of color is a selection effect.As in Figure9,the sample separates into blue and red sequences.However,there is little,if any,trend of color with M NUV,0.1along either sequence.This is consistent with the conclusions from studies in the optical which indicate that one of the most important factors determining the evolution of a galaxy is its mass, which is much more closely related to the r-band luminosity than to the NUV luminosity (Kauffmann et al.2003b;Brinchmann et al.2004).3.2.Color Distributions as a Function of M r,0.1The volume-corrected number density of galaxies as a function of(NUV−r)0.1color is plotted in Figures12−14in0.5magnitude wide bins of M r,0.1.The error bars are the statistical errors only calculated using equation(6).Except for the most luminous bin,there is both a red and blue peak visible in each panel.Similar to previous optical CMDs,the red sequence dominates in the brighter bins.The red and blue sequences reach approximately equal strengths around M r,0.1=−21.75with the blue sequence becoming dominant at fainter luminosities.The relative number of red sequence galaxies reaches50%at about the same luminosity when dividing galaxies using the(u−r)color(Baldry et al.2004).Following Baldry et al.(2004),we attempted tofit Gaussians to the red and blue peaks in the color distributions in each M r,0.1bin although we employed a somewhat different√methodology.Wefit a single Gaussian of the form(1/。
