演講資訊

摘要：

We have used the IRSF Magellanic Clouds (MCs) Point Source Catalog to identify candidates of massive main sequence stars in the MCs. The OB star counts and their main sequence lifetimes are used to estimate average star formation rates (SFRs) in the past ～10 Myr. Using these OB star counts and assuming Salpeter's initial mass function, we find average SFRs of about 0.38 and 0.11 solar mass per year for the LMC and SMC, respectively. These SFRs are higher than those determined from the H-alpha luminosities for the LMC and SMC. We suggest that this discrepancy is likely caused by the escape of stellar UV radiation from the disk planes of the MCs. SFRs determined from combinations of H-alpha and infrared emission may be still subject to the optical thickness of the interstellar medium (ISM), and may be significantly underestimated, especially for galaxies with tenuous ISM, low metallicity and low dust content.