2. file:///D|/karthi/images/nasa/182000main_image_feature_865_ys_4.txt
Resembling an aerial fireworks explosion, this dramatic image of the energetic star WR124, taken by the Hubble Space Telescope, reveals that it is surrounded by hot clumps of gas being ejected into space at speeds of over 100,000 miles per hour.
Also remarkable are vast arcs of glowing gas around the star, which are resolved into filamentary, chaotic substructures, yet with no overall global shell structure. Though the existence of clumps in the winds of hot stars has been deduced through spectroscopic observations of their inner winds, Hubble resolves them directly in the nebula M1-67 around WR124 as 100 billion-mile wide glowing gas blobs. Each blob is about 30 times the mass of the Earth.
The massive, hot central star is known as a Wolf-Rayet star. This extremely rare and short-lived class of super-hot star is going through a violent, transitional phase characterized by the fierce ejection of mass. The blobs may result from the furious stellar wind that is unstable as it flows into space. As the blobs cool, they eventually will dissipate into space and so don't pose any threat to neighboring stars.
The star is 15,000 light-years away, located in the constellation Sagittarius. The picture was taken with Hubble's Wide Field Planetary Camera 2 in March 1997. The image is false-colored to reveal details in the nebula's structure.
Image credit: NASA/Yves Grosdidier (University of Montreal and Observatoire de Strasbourg), Anthony Moffat (Universitie de Montreal), Gilles Joncas (Universite Laval), Agnes Acker (Observatoire de Strasbourg)
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4. file:///D|/karthi/images/nasa/182970main_image_feature_874_ys_4.txt
RCW 79 is seen in the southern Milky Way, 17,200 light-years from Earth in the constellation Centaurus. The bubble is 70-light years in diameter, and probably took about one million years to form from the radiation and winds of hot young stars.
The balloon of gas and dust is an example of stimulated star formation. Such stars are born when the hot bubble expands into the interstellar gas and dust around it. RCW 79 has spawned at least two groups of new stars along the edge of the large bubble. Some are visible inside the small bubble in the lower left corner. Another group of baby stars appears near the opening at the top.
NASA's Spitzer Space Telescope easily detects infrared light from the dust particles in RCW 79. The young stars within RCW79 radiate ultraviolet light that excites molecules of dust within the bubble. This causes the dust grains to emit infrared light that is detected by Spitzer and seen here as the extended red features.
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6. file:///D|/karthi/images/nasa/182970main_image_feature_875_ys_4.txt
Dust makes this cosmic eye look red. This eerie Spitzer Space Telescope image shows infrared radiation from the well-studied Helix Nebula (NGC 7293), which is a mere 700 light-years away in the constellation Aquarius. The two light-year diameter shroud of dust and gas around a central white dwarf has long been considered an excellent example of a planetary nebula, representing the final stages in the evolution of a sun-like star.
Spitzer data show the nebula's central star is itself immersed in a surprisingly bright infrared glow. Models suggest the glow is produced by a dust debris disk. Even though the nebular material was ejected from the star many thousands of years ago, the close-in dust could be generated by collisions in a reservoir of objects analogous to our own solar system's Kuiper Belt or cometary Oort cloud. Formed in the distant planetary system, the comet-like bodies have otherwise survived even the dramatic late stages of the star's evolution.
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8. file:///D|/karthi/images/nasa/183094main_image_feature_ys_876_4.txt
Scientists have made the first conclusive discovery of water vapor in the atmosphere of a planet beyond our solar system, or exoplanet.
This artist's rendering shows a gas-giant exoplanet transiting across the face of its star. Infrared analysis by NASA's Spitzer Space Telescope of this type of system provided the breakthrough.
The planet, HD 189733b, lies 63 light-years away in the constellation Vulpecula. It was discovered in 2005 as it transited its parent star
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11. file:///D|/karthi/images/nasa/183212main_image_feature_877_ys_4.txt
Variable star V838 Monocerotis lies near the edge of our Milky Way Galaxy, about 20,000 light-years from our sun. Still, ever since a sudden outburst was detected in January 2002, this enigmatic star has taken the center of an astronomical stage. As astronomers watch, light from the outburst echoes across pre-existing dust shells around V838 Mon, progressively illuminating ever more distant regions.
This stunning image of swirls of dust surrounding the star was recorded by the Hubble Space Telescope in September 2006. The picture spans about 14 light-years. Astronomers expect the expanding echoes to continue to light up the dusty environs of V838 Mon for at least the rest of the current decade. Researchers have now found that V838 Mon is likely a young binary star, but the cause of its extraordinary outburst remains a mystery
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18. file:///D|/karthi/images/nasa/M31%20Andromeda%20Galaxy%20photo.txt
M31 Andromeda Galaxy photo
M31 has played a pivotal historical role in astronomy. Early observers saw the soft, foggy patch of glowing light as just another spiral nebula but weren't yet equipped with the knowledge to appreciate its nature. The true nature of M31 began to became clear in 1923. In that year Edwin Hubble, using the just completed 100 inch Hooker telescope at the Mount Wilson observatory, made his monumental discovery of Cepheid Variable stars in M31 and in one stroke forever changed the astronomical paradigm of the universe as we know it. Appropriately interpreting the cepheid data, Hubble was the first to appreciate the faint nebula in Andromeda as an quot;island universequot;, an immense galaxy in its own right, similar to our Milky Way. Hubble's work opened the door to the modern interpretation of the universe which we now know consists of countless galaxies all receding from each other. M31 has the distinction of being the nearest of all spirals at a distance of 2.5 million light years. Its disk, tilted toward earth by some 13 degrees, exposes the grandeur of its spiral structure and star systems to telescopic exploration.
M31, along with its near twin, the Milky Way, represent the two dominant giant galaxies of our Local Group which consists of some 40 members. Contrary to most galaxies which are receding away from each other, M31 and the Milky Way are actually moving toward each other and a close encounter or even a full collision may be in store for both galaxies in several billion years. Studies of globular clusters in M31 have revealed at least 4 different subpopulations including some much younger than those that exist in the Milky Way. These findings point to the strong possibility that the galaxy we know as M31 may have been formed by the cannibalization of numerous smaller galactic neighbors.
file:///D|/karthi/images/nasa/M31%20Andromeda%20Galaxy%20photo.txt7/28/2007 11:28:31 PM