Free Astronomy Magazine November-December 2015

SPACE CHRONICLES A shy galactic neighbour by ESO T he Sculptor Dwarf Galaxy — also known as the Sculptor Dwarf Elliptical or the Sculp- tor Dwarf Spheroidal — is a dwarf spheroidal galaxy, and is one of the fourteen known satellite galaxies or- biting the Milky Way (this faint galaxy should not be confused with the much brighter Sculptor Galaxy, NGC 253, in the same constellation). These galactic hitchhikers are locat- ed close by in the Milky Way’s exten- sive halo, a spherical region ex- tending far beyond our galaxy’s spi- ral arms. As indicated by its name, this galaxy is located in the southern constellation of Sculptor and lies about 280,000 light-years away from Earth. Despite its proximity, the gal- axy was only discovered in 1937, as its stars are faint and spread thinly across the sky. Although difficult to pick out, the Sculptor Dwarf Galaxy was among the first faint dwarf galaxies found orbiting the Milky Way. The tiny gal- axy’s shape intrigued astronomers at the time of its discovery, but nowa- days dwarf spheroidal galaxies play a more important role in allowing astronomers to dig deeply into the Universe’s past. The Milky Way, like all large gal- axies, is thought to have formed T he Sculptor Dwarf Galaxy, pic- tured in a new image from the Wide Field Imager camera, in- stalled on the 2.2-metre MPG/ESO telescope at ESO’s La Silla Obser- vatory, is a close neighbour of our galaxy, the Milky Way. De- spite their proximity, both galax- ies have very distinct histories and characters. This galaxy is much smaller, fainter and older than the Milky Way and appears here as a cloud of faint stars fil- ling most of the picture. [ESO]