The many "personalities" of our great galactic neighbor, the Andromeda
galaxy, are exposed in this new composite image from NASA's Galaxy
Evolution Explorer and the Spitzer Space Telescope.
The wide, ultraviolet eyes of Galaxy Evolution Explorer reveal Andromeda's
"fiery" nature -- hotter regions brimming with young and old stars. In
contrast, Spitzer's super-sensitive infrared eyes show Andromeda's
relatively "cool" side, which includes embryonic stars hidden in their
dusty cocoons.
Galaxy Evolution Explorer detected young, hot, high-mass stars, which are
represented in blue, while populations of relatively older stars are shown
as green dots. The bright yellow spot at the galaxy's center depicts a
particularly dense population of old stars.
Swaths of red in the galaxy's disk indicate areas where Spitzer found
cool, dusty regions where stars are forming. These stars are still
shrouded by the cosmic clouds of dust and gas that collapsed to form them.
Together, Galaxy Evolution Explorer and Spitzer complete the picture of
Andromeda's swirling spiral arms. Hints of pinkish purple depict regions
where the galaxy's populations of hot, high-mass stars and cooler,
dust-enshrouded stars co-exist.
Located 2.5 million light-years away, the Andromeda is our largest nearby
galactic neighbor. The galaxy's entire disk spans about 260,000
light-years, which means that a light beam would take 260,000 years to
travel from one end of the galaxy to the other. By comparison, our Milky
Way galaxy's disk is about 100,000 light-years across.
This image is a false color composite comprised of data from Galaxy
Evolution Explorer's far-ultraviolet detector (blue), near-ultraviolet
detector (green), and Spitzer's multiband imaging photometer at 24 microns
(red).
