Giant Galactic Binoculars Discover Odd Features of Milky Way's Tiny Companion Galaxy

An international team of astronomers using new Large Binocular Telescope (LBT) in Arizona has found that the Hercules Dwarf Galaxy, a recently discovered tiny companion to our Milky Way at a distance of 430,000 light years, has truly unusual properties. While basically all of its known peers in the realm of these dwarf galaxies are rather round, this galaxy appears highly flattened, either the shape of a disk or of a cigar.

The stars in many large galaxies are arranged in a disk-like configuration, as in our own Milky Way. Yet in smaller galaxies like the Hercules Dwarf, which despite its name has only a 10-millionth as many stars as the Milky Way, a disk-like configuration has never been observed before. Among the millions of well-studied galaxies none has ever been observed to have a cigar-like shape.

An explanation for the galaxy’s unusual shape is that it is being disrupted by the gravitational forces of the Milky Way, similar to another of the Milky Way's satellites, the Sagittarius Dwarf, which is 10 times closer to the Milky Way’s center than the Hercules Dwarf Galaxy, and hence more highly affected by the destructive "tidal forces" of the massive black hole at the Milky Way's core.

"The Hercules Dwarf Galaxy is either unlike any of the millions of galaxies studied so far, or circles our Galaxy on an extremely plunging orbit: an exceptional, unparalleled object at any rate", says Matthew Coleman of the Max Planck Institute for Astronomy in Germany, who headed this study.

These inferences were enabled by the very deep images provided by the brand-new Large Binocular Telescope (LBT), the largest single telescope in the world, which is located on the 3,190-meter high Mount Graham in Arizona. Two giant mirrors with a diameter of 8.4 meters each, are hosted on the same mount acting as gigantic field glasses.

Due to the impressive first pictures and results, the astronomers are now very confident that the $120 million project is on the way to open a new door for spectacular observations of planets, stars and galaxies.

Posted by Casey Kazan, adapted from a Max Planck Institute release.