Arches Cluster
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Arches Cluster
A cluster of about 150 hot, young stars concentrated within a radius of about 1 light-year, making it the most compact cluster of stars in our Galaxy. It lies some 25,000 light-years away near the galactic center and is named after a series of arch-shaped filaments, detected at radio wavelengths, that lie in its vicinity. X-ray observations by the Chandra X-ray Observatory have shown an envelope of 60-million-degree gas around the cluster that is thought to be heated by intense stellar winds from the member stars colliding with the surrounding medium. Studies of the Arches Cluster can be used to learn more about the environments of starburst galaxies in which this process occurs on a much larger scale.
Arches Cluster This composite image shows an envelope of 60-million-degree gas around the Arches Cluster. Observations from the Chandra X-ray Observatory, shown as the diffuse emission in the inset box, overlays a Hubble Space Telescope infrared image of the same region, in which some of the individual stars in the cluster can be seen as pointlike sources. Both the X-ray and infrared observations are shown in context of the spectacular filamentary structures that appear in radio wavelengths and that give the cluster its name. The radio data were obtained using the Very Large Array. NASA/STScI/NRAO
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Arches Cluster
| Arches Cluster | |
|---|---|
 Arches Cluster of young, massive stars. This image was obtained with NACO adaptive optics system on ESO’s Very Large Telescope. |
|
| Observation data (J2000 epoch) | |
| Constellation | Sagittarius |
| Right ascension | 17h 45m 50.5s |
| Declination | –28° 49′ 28″ |
| Distance | 25 kly (8.5 kpc) |
| Physical characteristics | |
| Notable features | Optically obscured |
| See also: Open cluster, List of open clusters | |
The Arches Cluster is the densest known star cluster in the Milky Way, and is located about 100 light years away from the center of our galaxy, in the constellation Sagittarius. Due to extremely heavy optical extinction by dust in this region, the cluster is obscured in the visual bands, and is observed in the X-ray, infrared, and radio bands. The radius of the cluster is approximately one light year. It contains about 150 young, very hot stars that are many times larger and more massive than our Sun.[1] Such stars live for only a few million years before exhausting their hydrogen fuel, due to their extreme luminosity. The cluster also contains hot gas, produced in shocks by collisions among the massive, high-velocity stellar winds flowing outwards from the stars.
This star cluster and the Quintuplet cluster, another massive young cluster in the region, are estimated to be two to four million years old. Although possibly larger and denser than the Quintuplet Cluster, it appears to be slightly younger. The most evolved stars are barely edging away from the main sequence while the Quintuplet Cluster includes a number of hot supergiants as well as a red supergiant and the Luminous Blue Variable The Pistol Star. The most massive of their stars are expected to become supernovas, forming neutron stars or black holes, or else be torn apart by tidal forces from the black hole known to lie at the Galactic center.[citation needed]
Research
Work by Donald Figer, an astronomer at the Rochester Institute of Technology suggests that 150 solar masses is the upper limit of stars in the current era of the universe.[2] He used the Hubble Space Telescope to observe about a thousand stars in the Arches cluster and found no stars over that limit despite a statistical expectation that there should be several.
References
- ^ "Espinoza et al. The massive star initial mass function of the Arches cluster". Astronomy and Astrophysic. 2009. doi:10.1051/0004-6361/20078597.
- ^ "NASA's Hubble Weighs in on the Heaviest Stars in the Galaxy". NASA News. 2005-03-09. http://www.nasa.gov/home/hqnews/2005/mar/HQ_05071_HST_galaxy.html. Retrieved 2006-08-04.
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