| Description: | Leo T may sound like the name of one of Mr. Moszkowicz mates, it is however a very small dwarf companion galaxy of the Milky Way that was discovered a few months ago by a group of UK astronomers on optical images of the Sloan Survey. Leo T is located about 1 million lightyears from us, in direction of the constellation of The Lion (hence, of course, the name). Several of such small Galactic companions are known, but Leo T is unusual as it is, by far, the smallest, lowest luminosity galaxy with recent star formation; most other small companions contain only old stars. WSRT observations I did last weekend add to the mystery. The white contours represent the gas density as detected by the WSRT, overlaid on the optical image taken by the UK astronomers with the Wide-Field Camera on the Isaac Newton Telescope at La Palma. The figure shows that this galaxy has a lot of gas. In fact, it turns out that the gas mass is about the same as the mass in stars. This makes Leo T very remarkable since the dwarf companions of the Milky Way usually contain no gas, or at most very little. The recent star formation and the large amount of gas are likely to be connected, by we do not understand why this occurs in Leo T and not in other dwarf galaxies. Detailed studies of the stars and of the gas will now be done to try to understand why this galaxy is so different from the rest, and what this implies for dwarf galaxies in general. |
