Satellites orbiting disc galaxies as our Milky Way modify the dynamical state of their hosts.

The galaxy Sagittarius is, by the standards of the universe, tiny. (1991) is solved, when they belong to the Sagittarius dwarf galaxy. Carbon Stars in the Sagittarius Dwarf Galaxy - Volume 192 - Patricia Whitelock, John Menzies, Mike Irwin, Michael Feast Skip to main content We use cookies to distinguish you from other users and to provide you with a better experience on our websites.

It lies about 3.4 million light-years away. The Sagittarius Dwarf Irregular Galaxy (SagDIG) is a dwarf galaxy in the constellation of Sagittarius. The carbon stars are not metal-rich as previously thought, but they have a metallicity comparable to the LMC, with an age be-tween 0.1–1 Gyr. star formation history and from measurements of the inter-galactic medium at higher redshifts (Madau & Dickinson 2014). A significant fraction of the Sagittar-ius dwarf carbon stars have luminosities fainter than the The Sagittarius galaxy is much smaller than the Milky Way, with only about 150,000 stars, all of which seem destined to end up in the bulge and halo of our own Galaxy. It has a roughly elliptical shape and is thought to contain as many stars as the Sagittarius Dwarf Elliptical Galaxy, the previous contender for closest galaxy to our location in the Milky Way.

stars from Azzopardi et al.

But don’t sound the funeral bells for the little galaxy quite yet; the ingestion of the Sagittarius dwarf will take another 100 million years or so, and the stars themselves will survive. The discovery of the Sagittarius dwarf galaxy and the subsequent discovery of streams in the Milky Way halo suggest that a large fraction of the halo may be built from destroyed dwarf galaxies. (SagDIG should not be confused with the Sagittarius Dwarf Elliptical Galaxy, SagDEG, a satellite galaxy of the Milky Way discovered decades later in the same constellation.) The Sagittarius Dwarf Irregular Galaxy (aka Sgr dIG, ESO 594-4, UKS 1927-17.7; SagDIG from now on) makes a promis-ing environment to find very metal-poor, resolved massive stars.

The plane of the Milky Way according to Gaia data, with its largest known dwarf galaxy, the Sagittarius Dwarf Spheroidal Galaxy. It was discovered by Cesarsky et al. By combining Gaia DR2 data and modern Colour-Magnitude diagram fitting techniques, we have shown that repeated encounters between our Galaxy and Sagittarius triggered important star formation as well.