GALEX Celebrates Anniversary of First Light
Celebrating one year since the launch of GALEX on April 28, 2003, this ultraviolet image of Messier 81 and Messier 82 (M81 & M82), a pair of galaxies lying 10 Million Light Years distant, illustrates the satellite's unique window on the Universe. The diameter of the image on the sky is 1.2 degrees, or more than twice the diameter of the full moon.
The great spiral galaxy M81, similar in size and brightness to our Milky Way galaxy, is in the lower half of the image. The stars in its spiral arms have formed within the last 100 million years, as have most of the stars in a nearby dwarf galaxy just to the left of M81.
GALEX reveals that star formation is occurring quite distant from the nucleus of M81 in the faint blue extensions to the brighter spiral arms.
The nucleus, or center of M81, shines from the light of 10 billion year old stars near the end of their lives, which produce their energy by burning helium into carbon. These stars are cooler (and thus appear more red) then the younger hotter stars in the spiral arms of M81.
The upper half of the full GALEX field of view shows the remarkable star forming galaxy M82.
Star formation is so violent in this galaxy that gas and dust is being expelled perpendicular to its disk which we view on its side. Once thought to be an exploding galaxy; the flows are now known to be caused by the supernova explosions from the young stars in this turbulent galaxy. |
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