Cosmic grandeur: the Sculptor Galaxy

Infrared view of galaxy NGC 253

NGC 253 is one of the closest galaxies to our own. At infrared wavelengths shown here, dust clouds in the galaxy’s spiral arms become nearly transparent and a host of cool, red stars can be seen.

  • Sculptor Galaxy, also known as NGC 253
  • 13 million light-years from Earth
  • “Starburst” galaxy, in the throes of massive star formation

A new image of the Sculptor Galaxy (NGC 253) has been taken with the European Southern Observatory (ESO) VISTA telescope at the Paranal Observatory in Chile as part of one of its first major observational campaigns.

By observing in infrared light, VISTA’s view is less affected by dust in the galaxy, and reveals a myriad of cooler, red stars, as well as a prominent elongated belt of stars across the central region.

NGC 253 is one of the brightest galaxies in the sky. It is prominent enough to be seen with good binoculars and was discovered by Caroline Herschel from England in 1783.

A spiral galaxy that lies about 13 million light-years away, it is the brightest member of a small collection of galaxies called the Sculptor Group, one of the closest such groupings to our own Local Group of galaxies.

Part of its visual prominence comes from its status as a “starburst galaxy”, one in the throes of rapid star formation.

Infrared and visible light views of galaxy NGC 253

Comparison of the infrared (top) and visible light (bottom) views.

NGC 253 is also very dusty, which obscures the view of many parts of the galaxy. Seen from Earth, the galaxy is almost edge on, with the spiral arms clearly visible in the outer parts, along with a bright core at its centre.

See the full-size image here.

As VISTA works at infrared wavelengths it can see right through most of the dust that is such a prominent feature of the Sculptor Galaxy when viewed in visible light. Huge numbers of cooler stars that are barely detectable with visible-light telescopes suddenly can be seen.

The VISTA view reveals most of what was hidden by the thick dust clouds in the central part of the galaxy and allows a clear view of a prominent elongated section, or “bar”, of stars across the nuclear region — a feature that is not seen in visible light pictures. The majestic spiral arms now spread over the whole disc of the galaxy.

Astronomers are peeling away some of the mysteries of the Sculptor Galaxy. They are studying the myriad cool, red giant stars in the halo that surrounds the galaxy, measuring the composition of some of NGC 253’s small dwarf satellite galaxies, and searching for as yet undiscovered new objects such as globular clusters and ultra-compact dwarf galaxies that would otherwise be invisible without the deep VISTA infrared images.

Adapted from information issued by ESO / J. Emerson / VISTA / Cambridge Astronomical Survey Unit.

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