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Forensic Evidence of a Galac
…
| Title |
Forensic Evidence of a Galactic Collision |
| Description |
Astronomers have new evidence that the Andromeda spiral galaxy was involved in a violent head-on collision with the neighboring dwarf galaxy Messier 32 (M32) more than 200 million years ago. Infrared photographs taken with NASA's Spitzer Space Telescope revealed a never-before-seen dust ring deep within the Andromeda galaxy. When combined with a previously observed outer ring, the presence of both dust rings suggests that M32 plunged through the disk of Andromeda along Andromeda's polar axis approximately 210 million years ago. This image was obtained by the Infrared Array Camera (IRAC) at a wavelength of 8.0 microns. |
|
Forensic Evidence of a Galac
…
| Title |
Forensic Evidence of a Galactic Collision |
| Description |
Astronomers have new evidence that the Andromeda spiral galaxy was involved in a violent head-on collision with the neighboring dwarf galaxy Messier 32 (M32) more than 200 million years ago. Infrared photographs taken with NASA's Spitzer Space Telescope revealed a never-before-seen dust ring deep within the Andromeda galaxy. When combined with a previously observed outer ring, the presence of both dust rings suggests that M32 plunged through the disk of Andromeda along Andromeda's polar axis approximately 210 million years ago. This image was obtained by the Infrared Array Camera (IRAC) at a wavelength of 8.0 microns. |
|
Andromeda Makes a Splash
| Title |
Andromeda Makes a Splash |
| Description |
This infrared composite image from NASA's Spitzer Space Telescope shows the Andromeda galaxy, a neighbor to our Milky Way galaxy. The main image (top) highlights the contrast between the galaxy's choppy waves of dust (red) and smooth sea of older stars (blue). The panels below the main image show the galaxy's older stars (left) and dust (right) separately. Spiral galaxies tend to form new stars in their dusty, clumpy arms, while their cores are populated by older stars. The Spitzer view also shows Andromeda's dust lanes twisting all the way into the center of the galaxy, a region that is crammed full of stars. In visible-light pictures, this central region tends to be dominated by starlight. Astronomers used these new images to measure the total infrared brightness of Andromeda. Because the amount of infrared light given off by stars depends on their masses, the brightness measurements provided a novel method for "weighing" the Andromeda galaxy. According to this method, the mass of the stars in Andromeda is about110 billion times that of the sun, which is in agreement with past calculations. This means the galaxy contains about one trillion stars (because most stars are actually less massive than the sun). For comparison, the Milky Way is estimated to hold about 400 billion stars. A small, companion galaxy called NGC 205 is visible above Andromeda. Another companion galaxy called M32 can also been seen below the galaxy. The Andromeda galaxy, also known affectionately by astronomers as Messier 31, is located 2.5 million light-years away in the constellation Andromeda. It is the closest major galaxy to the Milky Way, making it the ideal specimen for carefully examining the nature of galaxies. On a clear, dark night, the galaxy can be spotted with the naked eye as a fuzzy blob. Andromeda'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, the Milky Way is about 100,000 light-years across. When viewed from Earth, Andromeda occupies a portion of the sky equivalent to seven full moons. Because this galaxy is so large, the infrared images had to be stitched together out of about 3,000 separate Spitzer exposures. The light detected by Spitzer's infrared array camera at 3.6 and 4.5 microns is sensitive mostly to starlight and is shown in blue and green, respectively. The 8-micron light shows warm dust and is shown in red. The contribution from starlight has been subtracted from the 8-micron image to better highlight the dust structures. |
|
Andromeda Makes a Splash
| Title |
Andromeda Makes a Splash |
| Description |
This infrared composite image from NASA's Spitzer Space Telescope shows the Andromeda galaxy, a neighbor to our Milky Way galaxy. The main image (top) highlights the contrast between the galaxy's choppy waves of dust (red) and smooth sea of older stars (blue). The panels below the main image show the galaxy's older stars (left) and dust (right) separately. Spiral galaxies tend to form new stars in their dusty, clumpy arms, while their cores are populated by older stars. The Spitzer view also shows Andromeda's dust lanes twisting all the way into the center of the galaxy, a region that is crammed full of stars. In visible-light pictures, this central region tends to be dominated by starlight. Astronomers used these new images to measure the total infrared brightness of Andromeda. Because the amount of infrared light given off by stars depends on their masses, the brightness measurements provided a novel method for "weighing" the Andromeda galaxy. According to this method, the mass of the stars in Andromeda is about110 billion times that of the sun, which is in agreement with past calculations. This means the galaxy contains about one trillion stars (because most stars are actually less massive than the sun). For comparison, the Milky Way is estimated to hold about 400 billion stars. A small, companion galaxy called NGC 205 is visible above Andromeda. Another companion galaxy called M32 can also been seen below the galaxy. The Andromeda galaxy, also known affectionately by astronomers as Messier 31, is located 2.5 million light-years away in the constellation Andromeda. It is the closest major galaxy to the Milky Way, making it the ideal specimen for carefully examining the nature of galaxies. On a clear, dark night, the galaxy can be spotted with the naked eye as a fuzzy blob. Andromeda'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, the Milky Way is about 100,000 light-years across. When viewed from Earth, Andromeda occupies a portion of the sky equivalent to seven full moons. Because this galaxy is so large, the infrared images had to be stitched together out of about 3,000 separate Spitzer exposures. The light detected by Spitzer's infrared array camera at 3.6 and 4.5 microns is sensitive mostly to starlight and is shown in blue and green, respectively. The 8-micron light shows warm dust and is shown in red. The contribution from starlight has been subtracted from the 8-micron image to better highlight the dust structures. |
|
Andromeda Makes a Splash
| Title |
Andromeda Makes a Splash |
| Description |
This infrared composite image from NASA's Spitzer Space Telescope shows the Andromeda galaxy, a neighbor to our Milky Way galaxy. The main image (top) highlights the contrast between the galaxy's choppy waves of dust (red) and smooth sea of older stars (blue). The panels below the main image show the galaxy's older stars (left) and dust (right) separately. Spiral galaxies tend to form new stars in their dusty, clumpy arms, while their cores are populated by older stars. The Spitzer view also shows Andromeda's dust lanes twisting all the way into the center of the galaxy, a region that is crammed full of stars. In visible-light pictures, this central region tends to be dominated by starlight. Astronomers used these new images to measure the total infrared brightness of Andromeda. Because the amount of infrared light given off by stars depends on their masses, the brightness measurements provided a novel method for "weighing" the Andromeda galaxy. According to this method, the mass of the stars in Andromeda is about110 billion times that of the sun, which is in agreement with past calculations. This means the galaxy contains about one trillion stars (because most stars are actually less massive than the sun). For comparison, the Milky Way is estimated to hold about 400 billion stars. A small, companion galaxy called NGC 205 is visible above Andromeda. Another companion galaxy called M32 can also been seen below the galaxy. The Andromeda galaxy, also known affectionately by astronomers as Messier 31, is located 2.5 million light-years away in the constellation Andromeda. It is the closest major galaxy to the Milky Way, making it the ideal specimen for carefully examining the nature of galaxies. On a clear, dark night, the galaxy can be spotted with the naked eye as a fuzzy blob. Andromeda'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, the Milky Way is about 100,000 light-years across. When viewed from Earth, Andromeda occupies a portion of the sky equivalent to seven full moons. Because this galaxy is so large, the infrared images had to be stitched together out of about 3,000 separate Spitzer exposures. The light detected by Spitzer's infrared array camera at 3.6 and 4.5 microns is sensitive mostly to starlight and is shown in blue and green, respectively. The 8-micron light shows warm dust and is shown in red. The contribution from starlight has been subtracted from the 8-micron image to better highlight the dust structures. |
|
Andromeda Makes a Splash
| Title |
Andromeda Makes a Splash |
| Description |
This infrared composite image from NASA's Spitzer Space Telescope shows the Andromeda galaxy, a neighbor to our Milky Way galaxy. The main image (top) highlights the contrast between the galaxy's choppy waves of dust (red) and smooth sea of older stars (blue). The panels below the main image show the galaxy's older stars (left) and dust (right) separately. Spiral galaxies tend to form new stars in their dusty, clumpy arms, while their cores are populated by older stars. The Spitzer view also shows Andromeda's dust lanes twisting all the way into the center of the galaxy, a region that is crammed full of stars. In visible-light pictures, this central region tends to be dominated by starlight. Astronomers used these new images to measure the total infrared brightness of Andromeda. Because the amount of infrared light given off by stars depends on their masses, the brightness measurements provided a novel method for "weighing" the Andromeda galaxy. According to this method, the mass of the stars in Andromeda is about110 billion times that of the sun, which is in agreement with past calculations. This means the galaxy contains about one trillion stars (because most stars are actually less massive than the sun). For comparison, the Milky Way is estimated to hold about 400 billion stars. A small, companion galaxy called NGC 205 is visible above Andromeda. Another companion galaxy called M32 can also been seen below the galaxy. The Andromeda galaxy, also known affectionately by astronomers as Messier 31, is located 2.5 million light-years away in the constellation Andromeda. It is the closest major galaxy to the Milky Way, making it the ideal specimen for carefully examining the nature of galaxies. On a clear, dark night, the galaxy can be spotted with the naked eye as a fuzzy blob. Andromeda'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, the Milky Way is about 100,000 light-years across. When viewed from Earth, Andromeda occupies a portion of the sky equivalent to seven full moons. Because this galaxy is so large, the infrared images had to be stitched together out of about 3,000 separate Spitzer exposures. The light detected by Spitzer's infrared array camera at 3.6 and 4.5 microns is sensitive mostly to starlight and is shown in blue and green, respectively. The 8-micron light shows warm dust and is shown in red. The contribution from starlight has been subtracted from the 8-micron image to better highlight the dust structures. |
|
Utraviolet Light Source in a
…
| Title |
Utraviolet Light Source in an Old Galaxy |
| Full Description |
Hubble Space Telescope's exquisite resolution has allowed astronomers to resolve, for the first time, hot blue stars deep inside an elliptical galaxy. The swarm of nearly 8,000 blue stars resembles a blizzard of snowflakes near the core (lower right) of the neighboring galaxy M32, located 2.5 million light-years away in the constellation Andromeda. Hubble confirms that the ultraviolet light comes from a population of extremely hot helium-burning stars at a late stage in their lives. Unlike the Sun, which burns hydrogen into helium, these old stars exhausted their central hydrogen long ago, and now burn helium into heavier elements. The observations, taken in October 1998, were made with the camera mode of the Space Telescope Imaging Spectrograph (STIS) in ultraviolet light. The STIS field of view is only a small portion of the entire galaxy, which is 20 times wider on the sky. For reference, the full moon is 70 times wider than the STIS field-of-view. Thirty years ago, the first ultraviolet observations of elliptical galaxies showed that they were surprisingly bright when viewed in ultraviolet light. Before those pioneering UV observations, old groups of stars were assumed to be relatively cool and thus extremely faint in the ultraviolet. Over the years since the initial discovery of this unexpected ultraviolet light, indirect evidence has accumulated that it originates in a population of old, but hot, helium-burning stars. Now Hubble provides the first direct visual evidence. |
| Date |
10/26/1999 |
| NASA Center |
Hubble Space Telescope Center |
|
The Trifid Nebula: Stellar S
…
| Title |
The Trifid Nebula: Stellar Sibling Rivalry |
|
Hubble Identifies Source of
…
| Title |
Hubble Identifies Source of Ultraviolet Light in an Old Galaxy |
|
Hubble Identifies Source of
…
| Title |
Hubble Identifies Source of Ultraviolet Light in an Old Galaxy |
|
NASA's Hubble Space Telescop
…
| Title |
NASA's Hubble Space Telescope Resolves a Planetary Nebula in the Large Magellanic Could |
| General Information |
What is an American Astronomical Society Meeting release? A major news announcement issued at an American Astronomical Society meeting, the premier astronomy conference. The NASA Hubble Space Telescope (HST) has imaged N66, a planetary nebula in the Large Magellanic Cloud (a satellite galaxy of our own Milky Way galaxy). The image was obtained at 10:41 p.m. EDT on June 26, 1991, using the European Space Agency's Faint Object Camera. |
|
NASA's Hubble Space Telescop
…
| Title |
NASA's Hubble Space Telescope Images the Dense Nucleus of Galaxy M32 |
|
Space Telescope Science Inst
…
| Title |
Space Telescope Science Institute Prepares a "Desktop Universe" For Astronomers |
|
Dwarf Elliptical Galaxy NGC
…
| Title |
Dwarf Elliptical Galaxy NGC 205 in the Local Group |
| Explanation |
Our Milky Way Galaxy [ http://antwrp.gsfc.nasa.gov/apod/milky_way.html ] is not alone. It is part of a gathering of about 25 galaxies known as the Local Group [ http://www.seds.org/messier/more/local.html ]. Members include the Great Andromeda Galaxy [ http://antwrp.gsfc.nasa.gov/apod/ap991114.html ] (M31), M32 [ http://antwrp.gsfc.nasa.gov/apod/ap991103.html ], M33 [ http://antwrp.gsfc.nasa.gov/apod/ap980721.html ], the Large Magellanic Cloud [ http://antwrp.gsfc.nasa.gov/apod/ap000222.html ], the Small Magellanic Cloud [ http://antwrp.gsfc.nasa.gov/apod/ap000430.html ], Dwingeloo 1 [ http://antwrp.gsfc.nasa.gov/apod/ap000109.html ], several small irregular galaxies [ http://www.seds.org/messier/irre.html ], and many dwarf elliptical [ http://nedwww.ipac.caltech.edu/level5/Ferguson/frames.html ] and dwarf spheroidal galaxies [ http://www.astro.uu.se/~ns/review.html ]. Pictured [ http://www.cfht.hawaii.edu/Science/Astros/Imageofweek/ciw061299.html ] on the lower left is one of the many dwarf ellipticals [ http://www.astro.psu.edu/users/pdurrell/dE.html ]: NGC 205 [ http://www.seds.org/messier/m/m110.html ]. Like M32 [ http://www.seds.org/messier/m/m032.html ], NGC 205 [ http://nedwww.ipac.caltech.edu/level5/Hodge/Hodge5_5.html ] is a companion to the large M31, and can sometimes be seen to the south of M31 [ http://www.seds.org/messier/m/m031.html ]'s center in photographs. The above image [ http://www.cfht.hawaii.edu/Science/Astros/Imageofweek/ciw061299.html ] shows NGC 205 to be unusual [ http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1998ApJ...499..209W ] for an elliptical galaxy [ http://antwrp.gsfc.nasa.gov/apod/elliptical_galaxies.html ] in that it contains at least two dust clouds [ http://antwrp.gsfc.nasa.gov/apod/ap990919.html ] (at 1 and 4 o'clock - they are visible but hard to spot) and signs of recent star formation [ http://antwrp.gsfc.nasa.gov/apod/stellar_nurseries.html ]. This galaxy is sometimes known as M110, although it was actually not part of Messier [ http://antwrp.gsfc.nasa.gov/apod/ap960626.html ]'s original catalog [ http://antwrp.gsfc.nasa.gov/apod/messier.html ]. |
|
Moon Over Andromeda
| Title |
Moon Over Andromeda |
| Explanation |
The Great Spiral Galaxy in Andromeda [ http://antwrp.gsfc.nasa.gov/apod/ap051222.html ] (aka M31), a mere 2.5 million light-years distant [ http://arxiv.org/abs/astro-ph/0511045 ], is the closest large spiral to our own Milky Way. Andromeda is visible to the unaided eye as a small, faint, fuzzy patch, but because its surface brightness is so low, casual skygazers [ http://www.physics.ucla.edu/~huffman/m31.html ] can't appreciate the galaxy's impressive extent in planet Earth's sky. This entertaining composite image compares the angular size [ http://chandra.harvard.edu/photo/scale.html ] of the nearby galaxy to a brighter, more familiar celestial sight. In it, a deep exposure of Andromeda [ http://www.caelumobservatory.com/gallery/m31abtp.shtml ], tracing beautiful blue star clusters in spiral arms far beyond the bright yellow core, is combined with a typical view of a nearly full Moon. Shown at the same angular scale, the Moon covers about 1/2 degree on the sky, while the galaxy is clearly [ http://www.regulusastro.com/regulus/papers/ m31/ ] several times that size. The deep Andromeda exposure also includes two bright satellite galaxies, M32 [ http://antwrp.gsfc.nasa.gov/apod/ap991103.html ] and M110 [ http://antwrp.gsfc.nasa.gov/apod/ap060908.html ] (bottom). |
|
Infrared Andromeda
| Title |
Infrared Andromeda |
| Explanation |
This wide, detailed Spitzer Space Telescope view [ http://www.spitzer.caltech.edu/Media/releases/ssc2006-14/ index.shtml ] features infrared light from dust (red) and old stars (blue) in Andromeda, a massive spiral galaxy a mere 2.5 million light-years away. In fact, with over twice the diameter of our own [ http://antwrp.gsfc.nasa.gov/apod/ap050825.html ] Milky Way, Andromeda is [ http://www.seds.org/Messier/m/m031.html ] the largest nearby [ http://www.seds.org/Messier/more/ local.html ] galaxy. Andromeda's population of bright young stars define its sweeping spiral arms in visible light images [ http://antwrp.gsfc.nasa.gov/apod/ap051222.html ], but here the infrared view clearly follows the lumpy dust lanes heated by the young stars as they wind even closer to the galaxy's core [ http://antwrp.gsfc.nasa.gov/apod/ap041227.html ]. Constructed to explore [ http://nedwww.ipac.caltech.edu/level5/ANDROMEDA_Atlas/ Hodge_contents.html ] Andromeda's infrared brightness [ http://coolcosmos.ipac.caltech.edu// ] and stellar populations, the full mosaic image is composed of about 3,000 individual frames. Two smaller companion galaxies, NGC 205 [ http://antwrp.gsfc.nasa.gov/apod/ap001023.html ] (below) and M32 [ http://antwrp.gsfc.nasa.gov/apod/ap991103.html ] (above) are also included in the combined fields. The data confirm that Andromeda (aka M31) houses around 1 trillion [ http://kokogiak.com/megapenny/thirteen.asp ] stars, compared to [ http://astronomy.swin.edu.au/~gmackie/billions.html ] 4 hundred billion [ http://kokogiak.com/megapenny/nine.asp ] for the Milky Way. |
|
Local Group Galaxy NGC 205
| Title |
Local Group Galaxy NGC 205 |
| Explanation |
The Milky Way Galaxy [ http://antwrp.gsfc.nasa.gov/apod/ap950908.html ] is not alone. It is part of a gathering of about 25 galaxies known as the Local Group [ http://www.csc.fi/jpr/galaxy/lbang.html ]. Members include the Great Andromeda Galaxy [ http://antwrp.gsfc.nasa.gov/apod/ap950724.html ] (M31), M32 [ http://antwrp.gsfc.nasa.gov/apod/ap960106.html ], M33 [ http://seds.lpl.arizona.edu/messier/m/m033.html ], the Large Magellanic Clouds [ http://antwrp.gsfc.nasa.gov/apod/ap950918.html ], the Small Magellanic Clouds [ http://antwrp.gsfc.nasa.gov/apod/ap950919.html ], Dwingeloo 1 [ http://antwrp.gsfc.nasa.gov/apod/ap951017.html ], several small irregular galaxies [ http://antwrp.gsfc.nasa.gov/apod/ap950728.html ], and many dwarf elliptical galaxies [ http://www.physics.mcmaster.ca/Grads/PRD2.html ]. Pictured is one of the many dwarf ellipticals: NGC 205. Like M32, NGC 205 is a companion to the large M31, and can sometimes be seen to the south of M31 [ http://seds.lpl.arizona.edu/messier/m/m031.html ]'s center in photographs. The above image [ http://crux.astr.ua.edu/gifimages/m110r.html ] shows this galaxy to be unusual for an elliptical galaxy [ http://antwrp.gsfc.nasa.gov/apod/ap950913.html ] in that it contains at least two dust clouds [ http://antwrp.gsfc.nasa.gov/apod/ap951107.html ] (at 7 and 11 o'clock - they are visible but hard to spot) and signs of recent star formation. This galaxy is sometimes known as M110, although it was actually not part of Messier [ http://antwrp.gsfc.nasa.gov/apod/lib/glossary.html#messier ]'s original catalog. |
|
Dwarf Elliptical Galaxy M32
| Title |
Dwarf Elliptical Galaxy M32 |
| Explanation |
Being the largest galaxy around can sometimes make you popular. Pictured is M31's companion galaxy M32 [ http://crux.astr.ua.edu/gifimages/m32.html ]. M31 [ http://antwrp.gsfc.nasa.gov/apod/ap950724.html ], the Andromeda galaxy, is the largest galaxy in our Local Group [ http://www.csc.fi/jpr/galaxy/lbang.html ] of galaxies - even our tremendous Milky Way Galaxy [ http://antwrp.gsfc.nasa.gov/apod/ap950908.html ] is smaller. Little M32 is visible in most pictures of M31 - it is the small circular spot north of M31's center. M32 is a dwarf elliptical galaxy [ http://www.physics.mcmaster.ca/Grads/PRD2.html ]. Elliptical galaxies [ http://sousun1.phys.soton.ac.uk/PH308/galaxies/ellipticals.html ] have little or no measurable gas [ http://antwrp.gsfc.nasa.gov/apod/lib/glossary.html#hydrogen ] or dust [ http://antwrp.gsfc.nasa.gov/apod/lib/glossary.html#dust ] - they are composed completely of stars [ http://antwrp.gsfc.nasa.gov/apod/lib/glossary.html#star ] and typically appear more red than spiral galaxies [ http://antwrp.gsfc.nasa.gov/apod/ap951218.html ]. Elliptical galaxies [ http://antwrp.gsfc.nasa.gov/apod/ap950913.html ] do not have disks - they generally have oblong shapes and therefore show elliptical profiles on the sky. |
|
The Aquarius Dwarf
| Title |
The Aquarius Dwarf |
| Explanation |
Our Milky Way Galaxy [ http://antwrp.gsfc.nasa.gov/apod/milky_way.html ] is not alone. It is part of a gathering of about 50 galaxies known as the Local Group [ http://www.seds.org/messier/more/local.html ]. Members include the Great Andromeda Galaxy [ http://antwrp.gsfc.nasa.gov/apod/ap021021.html ] (M31), M32 [ http://antwrp.gsfc.nasa.gov/apod/ap991103.html ], M33 [ http://antwrp.gsfc.nasa.gov/apod/ap021202.html ], the Large Magellanic Cloud [ http://antwrp.gsfc.nasa.gov/apod/ap010804.html ], the Small Magellanic Cloud [ http://antwrp.gsfc.nasa.gov/apod/ap000430.html ], Dwingeloo 1 [ http://antwrp.gsfc.nasa.gov/apod/ap000109.html ], several small irregular galaxies [ http://www.seds.org/messier/irre.html ], and many dwarf elliptical [ http://nedwww.ipac.caltech.edu/level5/Ferguson/frames.html ] and dwarf spheroidal galaxies [ http://www.astro.uu.se/~ns/review.html ]. Pictured above is the Aquarius Dwarf [ http://www.seds.org/~spider/spider/LG/aqr_dw.html ], a faint dwarf irregular galaxy over 3 million light years [ http://chandra.harvard.edu/photo/cosmic_distance.html ] away. An earlier [ http://antwrp.gsfc.nasa.gov/apod/ap970329.html ] APOD [ http://antwrp.gsfc.nasa.gov/apod/ap960204.html ] erroneously identified [ http://www.solstation.com/x-objects/sag-deg.htm ] the above image as the Sagittarius Dwarf [ http://www.seds.org/messier/more/sagdeg.html ]. |
|
M32: Blue Stars in an Ellipt
…
| Title |
M32: Blue Stars in an Elliptical Galaxy |
| Explanation |
Elliptical galaxies [ http://antwrp.gsfc.nasa.gov/apod/ap961106.html ] are known for their old, red stars. But is this old elliptical [ http://www.seds.org/messier/elli.html ] up to new tricks? In recent years, the centers of elliptical galaxies [ http://www.windows.umich.edu/cgi-bin/tour.cgi?link=/the_universe/Ellipticals.html ] have been found [ http://antwrp.gsfc.nasa.gov/apod/ap991103.html http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1998AJ....116.2297P ] to emit unexpectedly high amounts of blue and ultraviolet light [ http://imagine.gsfc.nasa.gov/docs/science/know_l1/emspectrum.html ]. Most blue light from spiral galaxies [ http://antwrp.gsfc.nasa.gov/apod/ap990926.html ] originates from massive young hot stars [ http://antwrp.gsfc.nasa.gov/apod/ap991103.html ap981025.html ], in contrast to the red light from the old cool stars thought to compose ellipticals. In the above recently released, false-color photograph [ http://oposite.stsci.edu/pubinfo/pr/1999/40/pr-photos.html ] by the Hubble Space Telescope [ http://www.stsci.edu/hst/ ], the center of nearby dwarf elliptical M32 has actually been resolved and does indeed show thousands of bright blue stars. The answer [ http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1999AAS...194.0713B ] is probably that these blue stars [ http://oposite.stsci.edu/pubinfo/pr/1999/40/index.html ] are also old and glow blue, reaching relatively high temperatures by the advanced process [ http://zebu.uoregon.edu/textbook/se.html ] of fusing helium [ http://antwrp.gsfc.nasa.gov/htmltest/gifcity/msblues.html ], rather than hydrogen [ http://antwrp.gsfc.nasa.gov/apod/lib/glossary.html#hydrogen ], in their cores. M32 [ http://antwrp.gsfc.nasa.gov/apod/ap960106.html ] appears in many pictures as the companion galaxy to the massive Andromeda Galaxy [ http://antwrp.gsfc.nasa.gov/apod/ap971101.html ] (M31). |
|
Infrared Andromeda
| Title |
Infrared Andromeda |
| Explanation |
This wide, detailed Spitzer Space Telescope view [ http://www.spitzer.caltech.edu/Media/releases/ssc2006-14/ index.shtml ] features infrared light from dust (red) and old stars (blue) in Andromeda, a massive spiral galaxy a mere 2.5 million light-years away. In fact, with over twice the diameter of our own [ http://antwrp.gsfc.nasa.gov/apod/ap050825.html ] Milky Way, Andromeda is [ http://www.seds.org/Messier/m/m031.html ] the largest nearby [ http://www.seds.org/Messier/more/ local.html ] galaxy. Andromeda's population of bright young stars define its sweeping spiral arms in visible light images [ http://antwrp.gsfc.nasa.gov/apod/ap051222.html ], but here the infrared view clearly follows the lumpy dust lanes heated by the young stars as they wind even closer to the galaxy's core [ http://antwrp.gsfc.nasa.gov/apod/ap041227.html ]. Constructed to explore [ http://nedwww.ipac.caltech.edu/level5/ANDROMEDA_Atlas/ Hodge_contents.html ] Andromeda's infrared brightness [ http://coolcosmos.ipac.caltech.edu// ] and stellar populations, the full mosaic image is composed of about 3,000 individual frames. Two smaller companion galaxies, NGC 205 [ http://antwrp.gsfc.nasa.gov/apod/ap001023.html ] (below) and M32 [ http://antwrp.gsfc.nasa.gov/apod/ap991103.html ] (above) are also included in the combined fields. The data confirm that Andromeda (aka M31) houses around 1 trillion [ http://kokogiak.com/megapenny/thirteen.asp ] stars, compared to [ http://astronomy.swin.edu.au/~gmackie/billions.html ] 4 hundred billion [ http://kokogiak.com/megapenny/nine.asp ] for the Milky Way. |
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