The Tail of the Small Magellanic Cloud (2010 Jan 07)

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The Tail of the Small Magellanic Cloud

Explanation: A satellite galaxy of our Milky Way, the Small Magellanic Cloud is wonder of the southern sky, named for 16th century Portuguese circumnavigator Ferdinand Magellan. Some 200,000 light-years distant in the constellation Tucana, the small irregular galaxy's stars, gas, and dust that lie along a bar and extended "wing", are familiar in images from optical telescopes. But the galaxy also has a tail. Explored in this false-color, infrared mosaic from the Spitzer Space Telescope, the tail extends to the right of the more familiar bar and wing. Likely stripped from the galaxy by gravitational tides, the tail contains mostly gas, dust, and newly formed stars. Two clusters of newly formed stars, warming their surrounding natal dust clouds, are seen in the tail as red spots.

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The rapidly receding Large Magellanic Cloud (currently 157 kly distant) should be as far away as the Small Magellanic Cloud (currently 197 kly distant) in about 100 million years. Tidal effects from the Large Magellanic Cloud already exceed the tidal effects from the Milky Way by a factor of about ten. Is the Small Magellanic Cloud feeling these strong tidal effects from it's neighboring 'cloud?'

<<The infrared portrait of the Small Magellanic Cloud, taken by NASA's Spitzer Space Telescope, ...shows the main body of the Small Magellanic Cloud, which is comprised of the "bar" and "wing" on the left and the "tail" extending to the right. The bar contains both old stars (in blue) and young stars lighting up their natal dust (green/red). The wing mainly contains young stars. The tail contains only gas, dust and newly formed stars. Spitzer data has confirmed that the tail region was recently torn off the main body of the galaxy. Two of the tail clusters, which are still embedded in their birth clouds, can be seen as red dots. In addition, the image contains a galactic globular cluster in the lower left (blue cluster of stars) and emission from dust in our own galaxy (green in the upper right and lower right corners).

http://apod.nasa.gov/apod/ap100107.html

The data in this image are being used by astronomers to study the lifecycle of dust in the entire galaxy: from the formation in stellar atmospheres, to the reservoir containing the present day interstellar medium, and the dust consumed in forming new stars. The dust being formed in old, evolved stars (blue stars with a red tinge) is measured using mid-infrared wavelengths. The present day interstellar dust is weighed by measuring the intensity and color of emission at longer infrared wavelengths. The rate at which the raw material is being consumed is determined by studying ionized gas regions and the younger stars (yellow/red extended regions). The Small Magellanic Cloud, and its companion galaxy the Large Magellanic Cloud, are the two galaxies where this type of study is possible, and the research could not be done without Spitzer.

This image was captured by Spitzer's infrared array camera and multiband imaging photometer (blue is 3.6-micron light; green is 8.0 microns; and red is combination of 24-, 70- and 160-micron light). The blue color mainly traces old stars. The green color traces emission from organic dust grains (mainly polycyclic aromatic hydrocarbons). The red traces emission from larger, cooler dust grains.>>