About a year ago Stathis Athanasiou joined our team to work on cross-matching sources from the Hubble Space Telescope to those detected from the ASSESS observations. After a whole year of efforts he managed to complete his thesis and defend it successfully !
Details of the thesis
Title: Mass-loss rates of dusty massive stars in nearby galaxies
Abstract: The thesis was performed in the framework of the ERC project ASSESS which studies episodic mass loss in evolved massive stars. The fate of massive stars with initial masses greater than 8M_⨀ is largely determined by the mass-loss rate at the end of their lives. Red supergiants (RSGs) are the direct progenitors of Type II-P core collapse supernovae (SN), but the magnitude and impact of any mass loss during this phase are unknown. We determined the luminosity and mass-loss-rate values of 60 RSGs in the galaxy WLM using near and mid-IR photometry and the radiative transfer code DUSTY. Based on our findings, we estimate a median mass-loss rate of 10^(-4.9) M_⨀/year. This is significantly higher than mass-loss-rates found in the literature, primarily due to the absence of mid-infrared data at wavelengths longer than 5μm. Additionally archival images from HST were used to classify 378 dusty, evolved massive star candidates, selected photometrically in 12 nearby galaxies by the ASSESS project. The study resulted in the identification of 288 stars, 81 galaxies and 9 clusters. All the targets were examined one by one. These results will be incorporated in future papers of the ASSESS team that will provide a large catalogue of dusty massive stars.