Nearby star-forming dwarf galaxies with small masses and low metallicity offer insights into the cosmic history of galaxy assembly. In this framework, we present results from the first combined study of variable stars and star formation history of the Milky Way (MW) ”Ultra-Faint” dwarf (UFD) galaxy Leo T, based on F606W and F814W multiepoch 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, including one fundamental-mode RR Lyrae star and 10 Anomalous Cepheids with periods shorter than 1 day, thus suggesting the occurrence of multiple star formation episodes in this UFD, one of which about 10 Gyr ago produced the RR Lyrae star. A quantitative analysis of the star formation history, based on the comparison of the observed color-magnitude diagram (CMD) with a library of artificially generated CMDs, confirms that Leo T has experienced a complex star formation history dominated by two enhanced periods about 1.5 and 8 Gyr ago, respectively.
A long history of star formation in a low mass stellar system, Leo T
Cignoni, M.Primo
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2015-01-01
Abstract
Nearby star-forming dwarf galaxies with small masses and low metallicity offer insights into the cosmic history of galaxy assembly. In this framework, we present results from the first combined study of variable stars and star formation history of the Milky Way (MW) ”Ultra-Faint” dwarf (UFD) galaxy Leo T, based on F606W and F814W multiepoch 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, including one fundamental-mode RR Lyrae star and 10 Anomalous Cepheids with periods shorter than 1 day, thus suggesting the occurrence of multiple star formation episodes in this UFD, one of which about 10 Gyr ago produced the RR Lyrae star. A quantitative analysis of the star formation history, based on the comparison of the observed color-magnitude diagram (CMD) with a library of artificially generated CMDs, confirms that Leo T has experienced a complex star formation history dominated by two enhanced periods about 1.5 and 8 Gyr ago, respectively.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
