This enormous image (zoomable version), captured with ESO’s Visible and Infrared Survey Telescope (VISTA), is the largest infrared image (43,223 x 38,236 pixels, 661 MB) ever taken of the Small Magellanic Cloud, a spectacular, naked-eye companion galaxy to our own Milky Way.
This VISTA image of the Small Magellanic Cloud shows millions of stars. Image credit: ESO / VISTA / VMC.
The Small Magellanic Cloud lies approximately 200,000 light-years away, in the southern constellation of Tucana. It is a dwarf galaxy, the more petite twin of the Large Magellanic Cloud.
Both are also rather peculiarly shaped, as a result of interactions with one another and with the Milky Way itself.
Their relative proximity to Earth makes the Magellanic Clouds ideal candidates for studying how stars form and evolve.
However, while the distribution and history of star formation in these dwarf galaxies were known to be complex, one of the biggest obstacles to obtaining clear observations of star formation in galaxies is interstellar dust.
Enormous clouds of these tiny grains scatter and absorb some of the radiation emitted from the stars — especially visible light — limiting what can be seen by telescopes here on Earth. This is known as dust extinction.
The Small Magellanic Cloud is full of dust, and the visible light emitted by its stars suffers significant extinction.
Fortunately, not all electromagnetic radiation is equally affected by dust. Infrared radiation passes through interstellar dust much more easily than visible light, so by looking at the infrared light from a galaxy we can learn about the new stars forming within the clouds of dust and gas.
ESO’s VISTA telescope, part of Paranal Observatory in Chile, was designed to image infrared radiation.
The VISTA Survey of the Magellanic Clouds (VMC) is focused on mapping the star formation history of these galaxies, as well as mapping their 3D structures.
Millions of Small Magellanic Cloud stars have been imaged in the infrared thanks to this survey, providing an unparalleled view almost unaffected by dust extinction.
The whole frame of this massive image is filled with stars belonging to the Small Magellanic Cloud.
It also includes thousands of background galaxies and several bright star clusters, including 47 Tucanae at the right of the picture, which lies much closer to us than the dwarf galaxy.
The wealth of new information in the new image has been analyzed by a team of astronomers led by Stefano Rubele of the University of Padova. They have used cutting-edge stellar models to yield some surprising results.
The VMC has revealed that most of the stars within the Small Magellanic Cloud formed far more recently than those in larger neighboring galaxies.
This research was presented in a paper published in the Monthly Notices of the Royal Astronomical Society (arXiv.org preprint) in 2015.
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Stefano Rubele et al. 2015. The VMC survey – XIV. First results on the look-back time star formation rate tomography of the Small Magellanic Cloud. MNRAS 449 (1): 639-661; doi: 10.1093/mnras/stv141
