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National Astronomical Observatory of Japan

Record-breaking Faint Satellite Galaxy of the Milky Way Discovered

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ocation of the satellite galaxies of the Milky Way Galaxy, including newly found Virgo I
Location of the satellite galaxies of the Milky Way Galaxy, including newly found Virgo I. A rendition created by Mitaka software that enables three dimensional viewing. Original size (120KB)

An international team led by researchers from Tohoku University has found an extremely faint dwarf satellite galaxy of the Milky Way. The team's discovery is part of the ongoing Subaru Strategic Survey using Hyper Suprime-Cam. The satellite, named Virgo I, lies in the direction of the constellation Virgo. At the absolute magnitude of -0.8 in the optical waveband, it may well be the faintest satellite galaxy yet found. Its discovery suggests the presence of a large number of yet-undetected dwarf satellites in the halo of the Milky Way and provides important insights into galaxy formation through hierarchical assembly of dark matter.

The team's finding is published in the Astrophysical Journal in its November 14, 2016 on-line version and November 20, 2016 in the printed version, Volume 832, Number 1. The title of the paper is "A New Milky Way Satellite Discovered in the Subaru/Hyper Suprime-Cam Survey" by D. Homma et al..

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