TheSculptor Dwarf Galaxy (also known asSculptor Dwarf Elliptical Galaxy or theSculptor Dwarf Spheroidal Galaxy, and formerly as theSculptor System) is adwarf spheroidal galaxy that is a satellite of theMilky Way. Thegalaxy lies within theconstellationSculptor. It was discovered in 1937 by American astronomerHarlow Shapley using the 24-inch Bruce refractor atBoyden Observatory.[5][6] The galaxy is located about 290,000light-years away from theSolar System. The Sculptor Dwarf contains only 4 percent of the carbon and other heavy elements in our own galaxy, the Milky Way, making it similar to primitive galaxies seen at the edge of the universe.[7]
Themetallicity of Sculptor dwarf appears to be broken up into two distinct groups, one with [Fe/H] = −2.3 and the other with [Fe/H] = −1.5.[8] Similar to many of the otherLocal Group galaxies, the older metal-poor segment appears more extended than the younger metal-rich segment.[9] Using cosmological numerical simulations, it has been recently argued that Sculptor's two distinct stellar populations would be the tell-tale sign of a past merger between Sculptor and another small dwarf galaxy companion.[10]
The Sculptor Dwarf is home to the most metal-poor star outside of the Milky Way, known as AS0039, with a metallicity of [Fe/H] = −4.11. Unlike other known metal-poor stars, it has a lowcarbon abundance and an unusual ratio ofalpha elements, suggesting it may have been formed in the aftermath of aPopulation III star hypernova.[11]
Using bothHubble Space Telescope andGaia observations 12 years apart, about 100 stars in the galaxy were mapped accurately, and 3D motions of about 10 of those stars enable trajectories to be mapped as well.[12]
