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یه بغل ستاره ، همین حوالی !!!
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[تصویر:  13523707761.jpg]




The Milky Way and other galaxies in the universe harbor many young star
clusters and associations that each contain hundreds to thousands of
hot, massive, young stars known as O and B stars. The star cluster
Cygnus OB2 contains more than 60 O-type stars and about a thousand
B-type stars. Deep observations with NASA’s Chandra X-ray Observatory
have been used to detect the X-ray emission from the hot outer
atmospheres, or coronas, of young stars in the cluster and to probe how
these fascinating star factories form and evolve. About 1,700 X-ray
sources were detected, including about 1,450 thought to be stars in the
cluster. In this image, X-rays from Chandra (blue) have been combined
with infrared data from NASA’s Spitzer Space Telescope (red) and optical
data from the Isaac Newton Telescope (orange).




Young stars ranging in age from one million to seven million years were
found. The infrared data indicates that a very low fraction of the
stars have circumstellar disks of dust and gas. Even fewer disks were
found close to the massive OB stars, betraying the corrosive power of
their intense radiation that leads to early destruction of their disks.
There is also evidence that the older population of stars has lost its
most massive members because of supernova explosions. Finally, a total
mass of about 30,000 times the mass of the sun is derived for Cygnus
OB2, similar to that of the most massive star forming regions in our
Galaxy. This means that Cygnus OB2, located only about 5,000 light years
from Earth, is the closest massive star cluster.




NASA's Marshall Space Flight Center in Huntsville, Ala., manages the
Chandra program for NASA's Science Mission Directorate in Washington.
The Smithsonian Astrophysical Observatory controls Chandra's science and
flight operations from Cambridge, Mass.




Credits: X-ray: NASA/CXC/SAO/J.Drake et al, Optical: Univ. of Hertfordshire/INT/IPHAS, Infrared: NASA/JPL-Caltech

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