|What is this?||The Small Magellanic Cloud, a satellite galaxy of our own Milky Way|
|Where is it in the sky?||In the constellation of Tucana|
|How big is it?||The Small Magellanic Cloud is around one twentieth of the size of the Milky Way|
|How far away is it?||It is around 200,000 light years away from the centre of the Milky Way|
|What do the colours represent?||Red and green show colder material seen by Herschel, while blue is warmer dust seen by Spitzer|
The Small Magellanic Cloud is a small galaxy that is orbitting our own Milky Way. At only around 7,000 light years across it is too small to have formed spiral arms, and has an irregular structure. In this image, combining data from both Herschel and NASA’s Spitzer space telescope, the dust between the stars shows two main regions: the bright bar on the right, and the “wing” of the galaxy stretching out to the left. Embedded in the cool dust (seen in red and green) are regions of active star formation (seen in blue and white), which are being heated by young stars within.
In visible light only the bar across the centre of the galaxy shines brightly, and can be even seen with the naked eye from the southern hemisphere. It is joined in the night sky by the larger, brighter Large Magellanic Cloud, and between them they allow the detailed study of star formation and evolution in a galaxy other than our own. The “Clouds of Magellan” are named after Portugese explorer Ferdinand Magellan who, while by no means the first to see them, observed them during his voyage of 1519.
“Studying these galaxies offers us the best opportunity to study star formation outside of the Milky Way,” said Margaret Meixner, an astronomer at the Space Telescope Science Institute, Baltimore, Md., and principal investigator for the mapping project. “Star formation affects the evolution of galaxies, so we hope understanding the story of these stars will answer questions about galactic life cycles.”
The Small Magellanic Cloud is the second largest satellite galaxy of the Milky Way, and the fifth largest galaxy in our Local Group (after the Milky Way, the Andromeda Galaxy, the Triangulum galaxy and the Large Magellanic Cloud). Its diminuitive size means that the composition of the material is slightly different from that in the larger galaxies, being slightly defficient in heavier elements such as carbon and oxygen. This slows the cycle of starbith and death, giving astronomers a close-up view of the environment in which stars were forming billions of years ago.