25.04.2017
Michalis Kourniotis/Alceste Bonanos
Observatory of Athens(Greece)
Yellow Hypergiants in M33
NELIOTA: ESA's NEO Lunar Impact Monitoring Project at the National Observatory of Athens
STRESZCZENIE
The evolution of massive stars surviving the red supergiant (RSG) stage remains unknown due to the rarity of such objects. The yellow hypergiants (YHGs) are the warm counterparts of post-RSG classes, which are characterized by atmospheric instability and high mass-loss rates. In the present work, I aim to increase the number of YHGs in M33 and thus to contribute to a better understanding of the late evolution of intermediate massive stars. I exploit archival infrared and long-term optical photometry to select dusty targets and detect variability typical of the outbursts of YHGs. Optical spectroscopy of the selected targets was obtained and SED-fitting was performed to provide evidence of extended atmospheric structures and circumstellar dust. The method suggests the discovery a YHG candidate and several dusty post-RSG candidates in M33, which are recommended for follow-up spectroscopy. Application of the method to other Local Group galaxies that are subject to the deep multi-band monitoring of PANSTARRS1 will increase the number of YHGs, thus providing observational constraints to the poorly-understood post-RSG evolution in diverse environments.

NELIOTA is an activity launched by the European Space Agency (ESA) at the National Observatory of Athens in February, 2015. It aims to determine the distribution and frequency of small near-earth objects (NEOs) by monitoring lunar impact flashes. The NELIOTA project has established an operational system that started monitoring the Moon for faint NEO impacts in early 2017, using the 1.2m Kryoneri telescope, located in the Northern Peloponnese, in Greece. The NELIOTA campaign will last for 22 months. In this talk, I will present the project and first results of the NELIOTA campaign.

O PRELEGENCIE
Michalis Kourniotis received his BSc from the Department of Mathematics of the University of Athens in 2005. He obtained his MSc degree in Applied Mathematics from the University of Athens in 2008 and his MSc degree in Astrophysics, Astronomy and Mechanics from the Department of Physics of the University of Athens in 2013, in collaboration with the Institute of Astronomy, Astrophysics, Space Applications and Remote Sensing of the National Observatory of Athens. He is currently a PhD candidate in the field of Observational Astrophysics.

Alceste Bonanos obtained her B.A. in Physics and Astronomy from Wellesley College (USA) in 2000, her M.A. in Astronomy from Harvard University (USA) in 2002 and her PhD in Astronomy from Harvard University (USA) in 2005. She was a Vera Rubin Fellow at the Carnegie Institution for Science (USA) from 2005-2008, and a Giacconi Fellow at the Space Telescope Science Institute (USA) from 2008-2009. She joined IAASARS, National Observatory of Athens, in September 2009 and since March 2017 is a Senior Researcher.