Image of the Day: New View of Andromeda Galaxy

M31 lies 2.5 million light-years away in the constellation Andromeda and is the nearest large spiral galaxy to our own. Under a clear, dark sky, it can be seen as a misty patch with the naked eye. In a break from its usual task of searching for distant cosmic explosions, NASA's Swift satellite has acquired the highest-resolution view of a neighboring spiral galaxy ever attained in the ultraviolet (see below). The galaxy, known as M31 in the constellation Andromeda, is the largest and closest spiral galaxy to our own.

"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."

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.

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.

 

Several features are immediately apparent in the new mosaic. The first is the striking difference between the galaxy's central bulge and its spiral arms. "The bulge is smoother and redder because it's full of older and cooler stars," Immler explained. "Very few new stars form here because most of the materials needed to make them have been depleted."Dense clusters of hot, young, blue stars sparkle beyond the central bulge. As in our own galaxy, M31's disk and spiral arms contain most of the gas and dust needed to produce new generations of stars. Star clusters are especially plentiful in an enormous ring about 150,000 light-years across. What triggers the unusually intense star formation in Andromeda's "ring of fire"? Previous studies have shown that tides raised by the many small satellite galaxies in orbit around M31 help boost the interactions within gas clouds that result in new stars. 

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." 

"Swift is surveying nearby galaxies like M31 so astronomers can better understand star- formation conditions and relate them to conditions in the distant galaxies where we see gamma-ray bursts occurring," said Neil Gehrels, the mission's principal investigator at NASA Goddard. Since Swift's November 2005 launch, the satellite has detected more than 400 gamma-ray bursts -- massive, far-off explosions likely associated with the births of black holes.

Source:

http://www.nasa.gov/mission_pages/swift/bursts/uv_andromeda.html

Comments

[SiliconJon]

That the Andromeda galaxy is only 11X further away than the galaxy is itself wide is something I had not taken note of before. Pretty cool, but still amazingly far away by current capabilities.

[claudio]

Extraordinary picture : Fantastic.

Andromeda our neighbour large Galaxy of the 'Local Group' is believed to have a total mass just less than that of our Milky way even if much larger in the size of the disk.

The nice matter is that the two Galaxies are moving at fantastic speed to crash to each other ...in spite of any Hubble inflation theory of the universe...that however may be somewhat true on a very large scale.

Andromeda has a gigantic black hole in its center pictured by Chandra at X-ray spectrum....as the Milky way has the Sagittarius A our center giga-black hole.

Since we are at the outskirt of Sagittarius arm we DO not see much of the central zone of Milky way screened to our view by the immense dusts of the Sagittarius arm...while we can see and will know much more about Andromeda.....strange ...but true.

In some hundreds of Millions Years (or may be Billions years) the two sisters are destined to merge...with obvious dramatic encounter....and fatal situation for many of the constellations of the two.

We humans however will NOT be there.....presumably.....therefore the matter is a curiosity rather than an effective trouble.

Regards to the magnificent Andromeda and to the publisher of the Fantastic piture.