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Locating Red Supergiants in the Galaxy NGC6822

Presentation #548.08 in the session “Stellar Evolution and Populations”.

Published onJan 11, 2021
Locating Red Supergiants in the Galaxy NGC6822

Using near-IR photometry, we are identifying red supergiants (RSG) in the irregular barred galaxy NGC6822 to compare with stellar evolutionary models. This research is complementary to our previous work, in which we located RSGs in the starburst galaxy IC10. These stars are the coolest of the evolved massive stars and have K and M spectral types and temperatures below 4100 K. Typically, they can be up to a thousand times the radius of the Sun and are therefore highly luminous. To find them in NGC6822, we first used GAIA parallax and proper motion values to filter out foreground red dwarfs before transforming the J and K magnitudes to effective temperatures and luminosities. Then, we used these values to apply RSG temperature and luminosity constraints. Next, we will compare our results to previous spectroscopically confirmed RSGs. Finally, we will use the color magnitude diagram to eliminate lower-mass AGB stars contaminants. Stellar evolutionary theory provides us with the expected quantity of RSG populations. Here, we propose a new sample of RSG candidates in NGC6822 that can be utilized as an observational test of such theory. By comparing our results in IC10 and NGC6822 with the RSG content studies done by our collaborators in M31, M33, and the LMC, our results can be used in further studies to test the effectiveness of RSG population projection methods. Additionally, by locating a population of RSGs in NGC6822, future possibilities for studying these massive stars with direct spectroscopic follow-up are created.

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