The Physical Properties of Red Supergiants: Comparing Theory and Observations

Philip Massey (1), Emily M. Levesque (2), Bertrand Plez, (3), and K. A. G. Olsen (4)

(1) Lowell Observatory; (2) Institute for Astronomy, University of Hawaii; (3) GRAAL, Universite Montpellier II; (4) Gemini Science Center, NOAO

Red supergiants (RSGs) are an evolved stage in the life of intermediate massive stars (less than 25 solar masses). For many years, their location in the H-R diagram was at variance with the evolutionary models. Using the MARCS stellar atmospheres, we have determined new effective temperatures and bolometric luminosities for RSGs in the Milky Way, LMC, and SMC, and our work has resulted in much better agreement with the evolutionary models. We have also found evidence of significant visual extinction due to circumstellar dust. Although in the Milky Way the RSGs contribute only a small fraction (than than 1 percent) of the dust to the interstellar medium (ISM), in starburst galaxies or galaxies at large look-back times, we expect that RSGs may be the main dust source. We are in the process of extending this work now to RSGs of higher and lower metallicities using the galaxies M31 and WLM.

Reference: Invited review, Massive Stars as Cosmic Engines, IAU Symp 250, ed. F. Bresolin, P. A. Crowther, & J. Puls (Cambridge Univ. Press)
Status: Conference proceedings