另眼系列之仙女座(M31)
来源:[url=http://gallery.spitzer.caltech.edu/Imagegallery/image.php?image_name=sig06-024]http://gallery.spitzer.caltech.e ... mage_name=sig06-024[/url]Amazing Andromeda Galaxy
The many "personalities" of our great galactic neighbor, the Andromeda galaxy, are exposed in this new composite image from NASA's Galaxy Evolution Explorer and the Spitzer Space Telescope.
The wide, ultraviolet eyes of Galaxy Evolution Explorer reveal Andromeda's "fiery" nature -- hotter regions brimming with young and old stars. In contrast, Spitzer's super-sensitive infrared eyes show Andromeda's relatively "cool" side, which includes embryonic stars hidden in their dusty cocoons.
Galaxy Evolution Explorer detected young, hot, high-mass stars, which are represented in blue, while populations of relatively older stars are shown as green dots. The bright yellow spot at the galaxy's center depicts a particularly dense population of old stars.
Swaths of red in the galaxy's disk indicate areas where Spitzer found cool, dusty regions where stars are forming. These stars are still shrouded by the cosmic clouds of dust and gas that collapsed to form them.
Together, Galaxy Evolution Explorer and Spitzer complete the picture of Andromeda's swirling spiral arms. Hints of pinkish purple depict regions where the galaxy's populations of hot, high-mass stars and cooler, dust-enshrouded stars co-exist.
Located 2.5 million light-years away, the Andromeda is our largest nearby galactic neighbor. The galaxy's entire disk spans about 260,000 light-years, which means that a light beam would take 260,000 years to travel from one end of the galaxy to the other. By comparison, our Milky Way galaxy's disk is about 100,000 light-years across.
This image is a false color composite comprised of data from Galaxy Evolution Explorer's far-ultraviolet detector (blue), near-ultraviolet detector (green), and Spitzer's multiband imaging photometer at 24 microns (red).
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[[i] 本帖最后由 寻找拉玛 于 2008-8-19 15:33 编辑 [/i]] 来源:[url]http://gallery.spitzer.caltech.edu/Imagegallery/image.php?image_name=ssc2005-20a[/url]
Three Faces of Andromeda
NASA's Spitzer Space Telescope has captured stunning infrared views of the famous Andromeda galaxy to reveal insights that were only hinted at in visible light.
Spitzer's 24-micron mosaic (top panel) is the sharpest image ever taken of the dust in another spiral galaxy. This is possible because Andromeda is a close neighbor to the Milky Way at a mere 2.5 million light-years away.
The Spitzer multiband imaging photometer's 24-micron detector recorded 11,000 separate snapshots to create this new comprehensive picture. Asymmetrical features are seen in the prominent ring of star formation. The ring appears to be split into two pieces, forming the hole to the lower right. These features may have been caused by interactions with satellite galaxies around Andromeda as they plunge through its disk.
Spitzer also reveals delicate tracings of spiral arms within this ring that reach into the very center of the galaxy. One sees a scattering of stars within Andromeda, but only select stars that are wrapped in envelopes of dust light up at infrared wavelengths.
This is a dramatic contrast to the traditional view at visible wavelengths (lower left panel), which shows the starlight instead of the dust. The center of the galaxy in this view is dominated by a large bulge that overwhelms the inner spirals seen in dust. The dust lanes are faintly visible in places, but only where they can be seen in silhouette against background stars.
The multi-wavelength view of Andromeda (lower right panel) combines images taken at 24 microns (blue), 70 microns (green), and 160 microns (red). Using all three bands from the multiband imaging photometer allows astronomers to measure the temperature of the dust by its color. The warmest dust is brightest at 24 microns while the coolest is most evident at 160 microns. The blue/white areas have the hottest dust, as seen in the bulge and in the star-forming areas along the arms. The cooler dust floating further out in the ring and arms are in the redder regions.
The data were taken on August 25, 2004, the one-year anniversary of the launch of the space telescope. The observations have been transformed into this remarkable gift from Spitzer -- the most detailed infrared image of the spectacular galaxy to date. 来源:[url=http://gallery.spitzer.caltech.edu/Imagegallery/image.php?image_name=ssc2004-12a]http://gallery.spitzer.caltech.e ... ge_name=ssc2004-12a[/url]
Morphology of Our Galaxy's 'Twin'
NASA's Spitzer Space Telescope has captured these infrared images of a nearby spiral galaxy that resembles our own Milky Way. The targeted galaxy, known as NGC 7331 and sometimes referred to as our galaxy's twin, is found in the constellation Pegasus at a distance of 50 million light-years. This inclined galaxy was discovered in 1784 by William Herschel, who also discovered infrared light.
The evolution of this galaxy is a story that depends significantly on the amount and distribution of gas and dust, the locations and rates of star formation, and on how the energy from star formation is recycled by the local environment. The new Spitzer images are allowing astronomers to "read" this story by dissecting the galaxy into its separate components.
The main image, measuring 12.6 by 8.2 arcminutes, was obtained by Spitzer's infrared array camera. It is a four-color composite of invisible light, showing emissions from wavelengths of 3.6 microns (blue), 4.5 microns (green), 5.8 microns (yellow) and 8.0 microns (red). These wavelengths are roughly 10 times longer than those seen by the human eye.
The infrared light seen in this image originates from two very different sources. At shorter wavelengths (3.6 to 4.5 microns), the light comes mainly from stars, particularly ones that are older and cooler than our Sun. This starlight fades at longer wavelengths (5.8 to 8.0 microns), where instead we see the glow from clouds of interstellar dust. This dust consists mainly of a variety of carbon-based organic molecules known collectively as polycyclic aromatic hydrocarbons. Wherever these compounds are found, there will also be dust granules and gas, which provide a reservoir of raw materials for future star formation.
These shorter- and longer-wavelength views are shown separately as insets. Perhaps the most intriguing feature of the longer-wavelength image is a ring of dust girdling the galaxy center. This ring, with a radius of nearly 20,000 light-years, is invisible at shorter wavelengths, yet has been detected at sub-millimeter and radio wavelengths. It is made up in large part of polycyclic aromatic hydrocarbons. Spitzer measurements suggest that the ring contains enough gas to produce four billion stars like the Sun. Starlight was systematically subtracted from the longer-wavelength picture to enhance dust features.
Three other galaxies are seen below NGC 7331, all about 10 times farther away. From left to right are NGC 7336, NGC 7335 and NGC 7337. The blue dots scattered throughout the images are foreground stars in the Milky Way; the red ones are galaxies that are even more distant.
The Spitzer observations of NGC 7311 are part of a large 500-hour science project, known as the Spitzer Infrared Nearby Galaxy Survey, which will comprehensively study 75 nearby galaxies with infrared imaging and spectroscopy. [url=http://www.bjp.org.cn/apod/2006-06/09/content_6558.htm]http://www.bjp.org.cn/apod/2006-06/09/content_6558.htm[/url]
[align=center][align=center][b][font=宋体][size=12pt]红外波段的仙女座[/size][/font][/b][/align][/align][align=center][align=center][b][font=宋体][size=12pt][/size][/font][/b] [/align][/align][align=center][align=center][b][font=宋体][size=12pt][url=http://www.nasa.gov/home/index.html][color=#0000ff][/color][/url]版权：Pauline Barmby (Harvard-Smithsonian CfA) et al., JPL, Caltech, NASA[/size][/font][/b][/align][/align][b][font=宋体][size=12pt] [/size][/font][/b]
[b][font=宋体][size=12pt] 说明：[/size][/font][/b][font=宋体][size=12pt]这张详细的[url=http://www.spitzer.caltech.edu/Media/releases/ssc2006-14/index.shtml][color=#0000ff]斯皮策太空望远镜长焦图像[/color][/url]描绘了来自仙女座中尘埃（红色）和年老恒星（蓝色）放射出的红外光，仙女座是一个质量巨大的旋涡星系，距离我们仅仅250万光年。事实上，[url=http://www.seds.org/Messier/m/m031.html][color=#0000ff]仙女座[/color][/url]的直径是[url=http://antwrp.gsfc.nasa.gov/apod/ap050825.html][color=#0000ff]我们[/color][/url]银河系两倍还要多，它是[url=http://www.seds.org/Messier/more/local.html][color=#0000ff]附近[/color][/url]最大的星系。在[url=http://antwrp.gsfc.nasa.gov/apod/ap051222.html][color=#0000ff]可见光图像[/color][/url]中，仙女座中明亮恒星的数量确定了它那巨大的旋臂，但是这张红外影像中可以清晰看见被年轻恒星加热的巨大尘埃带，它们的恒星风甚至接近了星系的中心。为了探索仙女座的[url=http://coolcosmos.ipac.caltech.edu//][color=#0000ff]红外亮度[/color][/url]和恒星数目，这整张图像是由大约3,000张单个画面合成的。两个较小的伴星系，[url=http://antwrp.gsfc.nasa.gov/apod/ap001023.html][color=#0000ff]NGC205[/color][/url]（下部）和[url=http://antwrp.gsfc.nasa.gov/apod/ap991103.html][color=#0000ff]M32[/color][/url]（上部）也包含在这张合成图像的范围内。收集到的数据证明仙女座(aka M31)内有大约1[url=http://kokogiak.com/megapenny/thirteen.asp][color=#0000ff]万亿[/color][/url]颗恒星，而我们银河系只有4,000[url=http://kokogiak.com/megapenny/nine.asp][color=#0000ff]亿[/color][/url]颗。（翻译：陈昌） [/size][/font]
[font=宋体][size=12pt][img]http://www.bjp.org.cn/files/2006-06/09/F_e9f783645a934c17935574aa0cc5bd2a_m31-irac_f.jpg[/img][/size][/font] 仙女座大星系是我最喜欢的星系之一啊，今次看到拉玛又发出这样的图我心动不已啊！！太美丽了！！ 爱死仙女星系 好漂亮~~~::070821_10.jpg:: 那里的外星人也一定很可爱~~::070821_10.jpg:: 使得。。我还不懂星系的时候 偶然看到后 就很喜欢她Andromeda 看到仙女座星系，那我们的银河星系也不会差到哪去吧！
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