The region that houses the highest density of young stars in our Galaxy, the Arches cluster (see inset), is surrounded by a scorching cloud of 60-million-degree gas, researchers say. A mere 25,000 light years from Earth, the Arches cluster is a well-studied region. But this is the first time astronomers have seen a young star cluster enveloped in such high-energy X-ray emissions.
Astronomers have long recognized that large, young stars can themselves emit X-rays. But the new findings, presented earlier this week at the American Astronomical Society's meeting in Pasadena, Calif., indicate that the X-rays can also arise from collisions between the winds from these stars. Furthermore, these X-rays appear to be as energetic as those observed in starburst galaxies. "The Arches cluster is one of the best local analogues of starburst galaxiesthe most prodigious stellar nurseries known, Casey Law of the Harvard-Smithsonian Center for Astrophysics notes.As such, researchers may be able to learn a lot more about starburst galaxies just by poking around in our own galactic backyard.
The results may also throw light on another mysterious phenomenon. "Our data suggest that the gas within the Arches cluster may get so hot that it escapes from the cluster, Cornelia Lang of the University of Massachusetts remarks. The Arches and other clusters like it may contribute to the reservoir of mysterious hot gas long observed near the Milky Way.