The Boötes Dwarf Galaxy, also known as Boötes I, is a satellite galaxy to the Milky Way. It lies approximately 197,000 light years from Earth. It is located in the constellation Boötes, the Herdsman.
Boötes I is a rather faint galaxy. It has an apparent visual magnitude of 13.1 and an absolute magnitude of -5.8. The galaxy’s luminosity is only 100,000 times that of the Sun.
Boötes Dwarf Galaxy (with falsely coloured stars), photo: V Belokurov, IoA Cambridge, Sloan Digital Sky Survey
It is one of the least luminous galaxies ever discovered. In fact, when it was discovered in 2006, it was the single least luminous galaxy ever seen, beating the previous record holder, an exceptionally dim galaxy in the constellation Ursa Minor.
The Boötes Dwarf is also one of the Milky Way’s most remote companion galaxies.
Boötes I is a dwarf spheroidal galaxy that seems to be tidally disrupted by our own galaxy, the Milky Way, which it orbits.
It is a metal and gas-poor galaxy. Its stars are spread out from one another and they look like stars in a very old globular cluster, suggesting that the galaxy itself is ancient.