Ultraviolet Rings of M31
From
NASA’s Astronomy
Picture of the Day
A mere 2.5 million
light-years away the Andromeda Galaxy, also known as M31, really is just next
door as large galaxies go.
So close and spanning some
260,000 light-years, it took 11 different image fields from the Galaxy
Evolution Explorer (GALEX) satellite's telescope to produce this
gorgeous portrait of the spiral galaxy in ultraviolet
light.
While its spiral arms
stand out in visible
light images of Andromeda, the arms look more like rings in the GALEX
ultraviolet view, a view dominated by the energetic light from hot, young,
massive stars.
As sites of intense star
formation, the rings have been interpreted as evidence Andromeda collided with
its smaller neighboring elliptical galaxy M32 more than 200 million years ago.
The large Andromeda galaxy and
our own Milky Way are the most massive members of the local galaxy group.
