September 17 2009 03:12 UTC | Views: 880 | Comments: 0 Posted by: TonyF in SWIFT
NASA's Swift satellite has acquired the highest-resolution view of a
neighboring spiral galaxy ever attained in the ultraviolet. The galaxy,
known as M31 in the constellation Andromeda, is the largest and closest
spiral galaxy to our own
Between May 25 and July 26, 2008, Swift's Ultraviolet/Optical Telescope
(UVOT) acquired 330 images of M31 at wavelengths of 192.8, 224.6, and
260 nanometers. The images represent a total exposure time of 24 hours.
"Swift reveals about 20,000 ultraviolet sources in M31, especially hot,
young stars and dense star clusters," said Stefan Immler, a research
scientist on the Swift team at NASA's Goddard Space Flight Center in
Greenbelt, Md. "Of particular importance is that we have covered the
galaxy in three ultraviolet filters. That will let us study M31's
star-formation processes in much greater detail than previously
possible."
This mosaic of M31 merges 330
individual images taken by the Ultraviolet/Optical Telescope aboard
NASA's Swift spacecraft. It is the highest-resolution image of the
galaxy ever recorded in the ultraviolet. The image shows a region
200,000 light-years wide and 100,000 light-years high (100 arcminutes
by 50 arcminutes)
Image Credit: NASA/Swift/Stefan Immler (GSFC) and Erin Grand (UMCP)
M31, also known as the Andromeda Galaxy, is more than 220,000
light-years across and lies 2.5 million light-years away. On a clear,
dark night, the galaxy is faintly visible as a misty patch to the naked
eye.
In 1885, an exploding star in M31's central bulge became bright enough
to see with the naked eye. This was the first supernova ever recorded
in any galaxy beyond our own Milky Way. "We expect an average of about
one supernova per century in galaxies like M31," Immler said. "Perhaps
we won't have to wait too long for another one."
