Milky Way Gobbles Up A Treat.
A map of stars in the outer region of the Milky Way as traced by the Sloan Digital Sky Survey. Streams of stars are seen throughout both the Northern (top) and Southern Galactic hemispheres, corresponding to small galaxies and star clusters which are in the process of being ingested by the Milky Way. The newest discovery is designated as the Triangulum Stream.
Trick or treat… Smell my feet… The Milky Way likes to eat! According the Yale astronomers, the Milky Way has been caught in the act – the act of ingesting a “small snack”.
By utilizing the Sloan Digital Sky Survey, researchers have discovered a stellar stream that may be the leftovers of an ancient star cluster being incorporated into our own galaxy. “The Milky Way is constantly gobbling up small galaxies and star clusters,” said Ana Bonaca, a Yale graduate student and lead author of a study forthcoming in Astrophysical Journal Letters. “The more powerful gravity of our Milky Way pulls these objects apart and their stars then become part of the Milky Way itself.”
This isn’t the first snack for the Milky Way, however. Astronomers have found other evidence of our galaxy consuming neighboring dwarfs. Bonaca feels this new stellar remnant is different though… she feels it’s a star cluster rather than a galaxy because the stream is narrow.
“Our discovery is more of a light snack than a big meal for the Milky Way,” says Marla Geha, associate professor of astronomy at Yale and a co-author of the study. “Studying this digestion process in detail is important because it gives us new insight into how all galaxies form and evolve.”
Named the Triangulum Stream, this new band of stars is the first to be found in the southern galactic sky. New, deep images are assisting astronomers in reconstructing how the Milky Way’s mass is distributed and further refining its dynamic structure.
Our MIlky Way would look like this
“Galaxies are believed to form hierarchically through the merger of smaller galaxies and still smaller star clusters. Stellar streams form as they are ripped apart by the gravitational force of galaxies. This process may be the primary way galaxies such as the Milky Way grow in mass,” the researchers say.
The Triangulum Stream was identified when astronomers began studying a new region just surveyed by the SDSS-III, an international program that’s mapping the sky through the use of wide-field photometry. Bonaca, Geha and co-author Nitya Kallivayalil, a Yale postdoctoral fellow, relied specifically on the survey’s Data Release 8, which included information about vast new areas of the southern galactic sky.
Original Story Source: Yale News. Submitted by Tammy Plotner for “Dave Reneke’s World of Space and Astronomy News”.
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