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Session: Stars, Planets and the Interstellar Medium

Name: Ms. Evangelia Christodoulou (NOA / NKUA)
Coauthors: Bonanos Alceste (National Observatory of Athens)
Munoz Sanchez Gonzalo (National Observatory of Athens)
de Wit Stephan (National Observatory of Athens)
Maravelias Grigoris (National Observatory of Athens)
Garcia Alvarez David (Instituto de Astrofisica de Canarias)
Antoniadis Kostas (National Observatory of Athens)
Type: Poster
Title: Near Infrared Spectroscopy of red supergiants in NGC 6822, IC 10 & WLM with EMIR
Abstract:

Near Infrared Spectroscopy of red supergiants in NGC 6822, IC 10 & WLM with EMIR The role of episodic mass loss in the evolution of massive stars remains largely unknown and thus it is not included in the stellar models. The ASSESS project is conducting an optical survey in the nearby Universe (12 galaxies with Z ~ 0.1 to 1.5 Zo) searching for evolved massive stars, primarily targeting those with infrared excess (i.e. circumstellar dust) which reveals mass loss. The results of this survey in the northern hemisphere have led to the secure spectral classification of twelve red supergiants (RSGs) in NGC 6822 and IC 10 (Ζ= 0.32 Zo and 0.45 Zo). Follow up spectroscopy has been acquired in the J-band for eight of them using the EMIR detector at the Grand Telescope of the Canarias. Also, we observed one target from the literature (WLM 14), expanding our metallicity range to 0.14 Zo, as we aim to study mass loss in the low metallicity regime. Such observations are needed because the effective temperature (Teff) measured from atomic lines in the J-band is more accurate than the one estimated using the TiO bands present in the optical spectra, as the latter form at larger radii and lower temperatures. Improved Teff estimations lead to more robust estimations of mass loss. We aspire to calibrate the temperature scale of RSG at low metallicities and use it to obtain mass loss measurements for the rest of our sample (~ 130 RSGs) for which infrared spectroscopy is not feasible. I will present initial results from the analysis of these observations.