Sweet Home
Milky Way a rare beauty
A newly discovered star-forming arm at the fringes of the Milky Way may be a vast, outer extension of the arm Scutum-Centaurus
A new study suggests the Milky Way doesn't need a makeover: It's already just about perfect. Astronomers base that assertion on their discovery of a vast section of a spiral, star-forming arm at the Milky Way's outskirts. The finding suggests that the galaxy is a rare beauty with an uncommon symmetry one half of the Milky Way is essentially the mirror image of the other half. Thomas Dame and Patrick Thaddeus of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., say the structure they've discovered is most likely the outer extension of the Scutum-Centaurus arm from the inner galaxy. The finding suggests that Scutum-Centaurus wraps all the way around the Milky Way, making it a symmetric counterpart to the galaxy's other major star-forming arm, Perseus. The two arms appear to extend from opposite ends of the galaxy's central, bar-shaped cluster of stars, each winding around the galaxy, the researchers note in an upcoming issue of Astrophysical Journal Letters. Dame found evidence for the new structure while reviewing galactic data on atomic hydrogen gas, which radiates at a radio wavelength of 21 centimeters. After tracing the extension of the arm in the 21-centimeter radio emission, "I was in the unique position of being able to walk up two flights of stairs to the roof of my building [at Harvard] and search for carbon monoxide emissions from molecular clouds using the CfA 1.2-meter radio telescope," says Dame. Molecular gas clouds contain the raw material for making stars.
For all latest news, follow The Daily Star's Google News channel.
Comments