Milky Way Galaxy Has Mirrorlike Symmetry
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, Massachusetts 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.
Image: A newly discovered star-forming arm at the fringes of the Milky Way may be a vast, outer extension of the arm Scutum-Centaurus. The finding suggests that the Milky Way has a rare symmetry, with one half of the galaxy the mirror image of the other half. (T. Dame/Robert Hurt)