By means of deep FORS1/VLT and ACS/Hubble Space Telescope observations of a wide area in the stellar system ? Cen we measured the luminosity function of main-sequence stars down to R = 22.6 and IF814W = 24.5. The luminosity functions obtained have been converted into mass functions and compared with analytical initial mass functions (IMFs) available in the literature. The mass function obtained, reaching M ~ 0.15Msolar, can be well reproduced by a broken power law with indices ? = -2.3 for M > 0.5Msolar and ? = -0.8 for M < 0.5Msolar. Since the stellar populations of ? Cen have been proved to be actually unaffected by dynamical evolution processes, the mass function measured in this stellar system should represent the best approximation of the IMF of a star cluster. The comparison with the MF measured in other Galactic globular clusters suggests that possible primordial differences in the slope of the low-mass end of their MF could exist.
Sollima A., Ferraro F. R., Bellazzini M. (2007). The mass function of Omega Centauri down to 0.15 Msolar. MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 381, 1575-1582 [10.1111/j.1365-2966.2007.12324.x].
The mass function of Omega Centauri down to 0.15 Msolar
SOLLIMA, ANTONIO;FERRARO, FRANCESCO ROSARIO;
2007
Abstract
By means of deep FORS1/VLT and ACS/Hubble Space Telescope observations of a wide area in the stellar system ? Cen we measured the luminosity function of main-sequence stars down to R = 22.6 and IF814W = 24.5. The luminosity functions obtained have been converted into mass functions and compared with analytical initial mass functions (IMFs) available in the literature. The mass function obtained, reaching M ~ 0.15Msolar, can be well reproduced by a broken power law with indices ? = -2.3 for M > 0.5Msolar and ? = -0.8 for M < 0.5Msolar. Since the stellar populations of ? Cen have been proved to be actually unaffected by dynamical evolution processes, the mass function measured in this stellar system should represent the best approximation of the IMF of a star cluster. The comparison with the MF measured in other Galactic globular clusters suggests that possible primordial differences in the slope of the low-mass end of their MF could exist.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
