| Title | Variability and Star Formation in Leo T, the Lowest Luminosity Star-forming Galaxy Known Today |
| Authors | Clementini, Gisella; Cignoni, Michele; Contreras Ramos, Rodrigo; Federici, Luciana; Ripepi, Vincenzo; Marconi, Marcella; Tosi, Monica; Musella, Ilaria |
| Bibcode | 2012ApJ...756..108C Search ADS ↗ |
| Abstract | We present results from the first combined study of variable stars and star formation history (SFH) of the Milky Way "ultra-faint" dwarf (UFD) galaxy Leo T, based on F606W and F814W multi-epoch archive observations obtained with the Wide Field Planetary Camera 2 on board the Hubble Space Telescope. We have detected 14 variable stars in the galaxy. They include one fundamental-mode RR Lyrae star and 11 Anomalous Cepheids with periods shorter than 1 day, thus suggesting the occurrence of multiple star formation episodes in this UFD, of which one about 10 Gyr ago produced the RR Lyrae star. A new estimate of the distance to Leo T of 409+29 - 27 kpc (distance modulus of 23.06 ± 0.15 mag) was derived from the galaxy's RR Lyrae star. Our V, V - I color-magnitude diagram (CMD) of Leo T reaches V ~ 29 mag and shows features typical of a galaxy in transition between dwarf irregular and dwarf spheroidal types. A quantitative analysis of the SFH, based on the comparison of the observed V, V - I CMD with the expected distribution of stars for different evolutionary scenarios, confirms that Leo T has a complex SFH dominated by two enhanced periods about 1.5 and 9 Gyr ago, respectively. The distribution of stars and gas shows that the galaxy has a fairly asymmetric structure. Based on archive data collected with the Wide Field Planetary Camera 2 on board the Hubble Space Telescope. |
| Objects | 1 Objects Search NED ↙ |
