The European Southern Observatory has released an enormous 43,223 x 38,236 pixel view of one of the Milky Way's closest galactic neighbors – the Small Magellanic Cloud (SMC). Located a mere 200,000 light-years from Earth, the SMC is only a twelfth of the distance to the Andromeda galaxy, making it an excellent target for studies aimed at improving our understanding of alien galaxies.
The Small Magellanic Cloud, as its name would suggest, is not as large, nor as perfectly formed as the Milky Way. In fact, the 15,000 light-year wide dwarf galaxy owes its unusual appearance to a complex gravitational tug of war between itself, the Milky Way and its nearby twin – the Large Magellanic Cloud.
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Attempts to image the Large and Small Magellanic Clouds with optical telescopes are frustrated by dense clouds of interstellar dust, which work to absorb or scatter radiation in the visible light spectrum. This is a phenomenon known as dust extinction.
However, astronomers are able to peek behind the dust veil by observing the SMC in the infrared spectrum. Infrared light has a longer wavelength than visible light, a characteristic that allows it to travel through the cosmic clouds while avoiding significant dust extinction.
Enter the ESO's Visible and Infrared Survey Telescope for Astronomy (VISTA). VISTA is an enormous purpose-built infrared telescope located at the Paranal Observatory in Chile, on a peak adjacent to the world-renowned (and imaginatively named) Very Large Telescope.
The Small Magellanic Cloud is located in the constellation of Tuscana, and is easily visible to the naked eye on a clear night (Credit: ESO, IAU and Sky & Telescope)
At the heart of VISTA is a powerful three-tonne camera, which observes the heavens with 16 cutting-edge infrared detectors. This camera, in conjunction with the telescope's 4.1-meter (13.4-ft) primary mirror, is currently engaged in six distinct public surveys that task VISTA with charting vast swathes of the southern night sky in astonishing detail.
The newly released mega-image of the SMC is the result of one such effort, known as the VISTA Magellanic Survey (VMS). This ambitious project is, in part, seeking to create a three-dimensional map of the SMC and LMC, and to gain a better understanding of the stellar formation history and populations that have – and are – shaping the twin galaxies.
VISTA's latest SMC offering represents the largest infrared image of the satellite galaxy ever taken. The vista, which is dominated by a sea of stars belonging to the SMC, is also studded with thousands of background galaxies. A zoomable version of the image is available on the ESO website.
Prominently featured in the top right of the image is the bright globular cluster 47 Tucanae, which despite appearing as part of the SMC, is actually located within the Milky Way, some 17,000 light-years from Earth. Analysis of the image is already yielding insights into the stellar population of the SMC, including the revelation that most of the stars that populate the dwarf galaxy formed recently in comparison to other nearby galaxies.
Scroll down to see an animated close-up look at the Small Magellanic Cloud, courtesy of the ESO.
A paper related to the image has been published in the Monthly Notices of the Astronomical Society.