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ATLANTA - Peering deep into a distant galaxy, astronomers have obtained a glimpse of what may be the youngest massive star clusters ever observed.
The discovery, announced today at a meeting of the American Astronomical Society by astronomers from the University of Wisconsin-Madison and University of Colorado, is important because it provides astronomers with a look inside stellar nurseries at massive clusters of stars in their infancy.
Estimated to be as young as 500,000 years, the star clusters are in the very earliest stages of development, analogous to the first day of life in human terms, the astronomers says.
"This is exciting because it may reveal the types of environments where globular clusters form," says Henry (Chip) Kobulnicky, a UW-Madison astronomer. "No one has ever seen a star cluster of any type, much less a possible globular cluster, at such a young age."
The discovery was made with the help of the Very Large Array (VLA), a huge, highly sensitive radio telescope located near Socorro, N.M. Using the VLA, Kobulnicky and colleague Kelsey Johnson of the University of Colorado, were able to look deep into a galaxy known as Henize 2-10 and penetrate obscuring clouds of dust and ionized gas surrounding at least five clusters consisting of hundreds of young, massive stars.
Common in galaxies, star clusters are tightly packed groups of hundreds to thousands of stars that are much more luminous and massive than the sun. Their ages are typically estimated to be several million years old. Globular clusters are similar, but far older - 8 to 12 billion years - and consist of stars more like the sun.
Free of the obscuring clouds of dust and gas found around stars in the earliest stages of their existence, most star clusters can be seen with conventional optical telescopes. However, stars coming to life within cocoons of dust and gas are hidden from view, but can be detected by the radio waves that pass through the obscuring clouds.
What the Wisconsin-Colorado team observed, says Kobulnicky, were five clusters of stars with an estimated 500 to 1,000 massive stars each in Henize 2-10, a galaxy located 32 million light years from Earth in the constellation Pyxis. Packed into relatively small areas of space - roughly an area the size of the distance between the sun and Alpha Centauri, the star nearest the sun - such dense clusters of massive stars are believed to evolve over billions of years into globular clusters such as the ones that orbit the Milky Way.
Knowing about the first stages of their development, according to Kobulnicky, is important because it will provide some insight into how such objects, which appear to be common in all galaxies, come into being.
The work was supported by NASA through grants to the universities in Wisconsin and Colorado. The VLA is operated by the National Radio Astronomy Observatory, an arm of the National Science Foundation.
Terry Devitt
trdevitt@facstaff.wisc.edu
608-262-8282