An Entire Galaxy, Seen in Ultraviolet

Written by Fraser Cain

NASA's Swift satellite is pretty jittery as space telescopes go. It's designed to wait until it detects a gamma ray burst, and then swing around quickly to start observing. But it's actually equipped with some sensitive instruments, including a wonderful telescope designed for observing in the ultraviolet. In between searching for gamma ray bursts, Swift found the time to build up the most detailed ultraviolet image of an entire galaxy ever taken.

The ultraviolet spectrum is outside the normal range of visual light that we can see with our eyes. But it can sure affect you. Spend to much time out in the sunlight, and the ultraviolet radiation will give you a sunburn.

Young, hot, newly forming stars also give off a tremendous amount of ultraviolet radiation. Look at a galaxy in the ultraviolet, and you see the regions of star formation.

And that's just what Swift did. The space telescope zeroed in on M33 - the Triangulum Galaxy. The galaxy is about half the size of the Milky Way, and located about 2.9 million light-years from Earth.

Even though it's relatively small, M33 is awash in star formation.

"The ultraviolet colors of star clusters tell us their ages and compositions," says Swift team member Stephen Holland of NASA Goddard. "With Swift’s high spatial resolution, we can zero in on the clusters themselves and separate out nearby stars and gas clouds. This will enable us to trace the star-forming history of the entire galaxy.”