부산대학교 도서관

The kinematics and chemical composition of stellar populations of different ages provide crucial information about the evolution of a galaxy. We aim to provide such information for IC 1613, an isolated, gas-rich, star-forming dwarf galaxy in the Local Group. We present here the results of a new spectroscopic study performed with MUSE, an integral-field spectrograph on the Very Large Telescope. We extracted from the data cubes more than 2000 sources from which we separated stellar objects for further spectroscopic analysis. The quality of the data set allowed us to obtain accurate classifications and line-of-sight velocities for about 800 stars. Our sample includes not only Red Giant Branch (RGB) and Main Sequence (MS) stars, but also a number of probable Be and C stars. We also obtained reliable metallicities for about 300 RGB stars. The kinematic analysis revealed for the first time the presence of stellar rotation with high significance. We found a general agreement with the velocity field of the neutral gas component, although the stars showed on average a larger velocity dispersion and slower rotation due to the asymmetric drift. When examining the kinematics of the different stellar components, MS stars appear to closely follow that of the gas, and the velocity dispersion seems to increase towards older stars. Chemical analysis of the RGB stars revealed mean properties comparable to those of other Local Group dwarf galaxies. Our work represents a step forward in understanding the internal processes governing the dynamical evolution of a low-mass galaxy.
Comment: Submitted to Astronomy & Astrophysics. Comments are welcomed