Yellow Supergiants and Post-red Supergiant Evolution in the Large Magellanic Cloud

Abstract

The empirical evidence for an upper-mass limit for the red supergiant (RSG) progenitors of the Type II-P SNe at about 18 MSun, raises questions about the fate of the most luminous, most massive RSGs. These stars may evolve back to warmer temperatures to end their lives as hotter stars or collapse directly to black holes. The yellow hypergiants, many with extensive circumstellar dust and high mass loss, are excellent candidates for post-RSG evolution. We have identified six high-luminosity yellow supergiants (YSGs) in the LMC with circumstellar dust, including two of the fast yellow pulsating supergiants (FYPS). We discuss their spectral energy distributions, mass lost, and mass-loss rates. Together with three additional FYPS, these nine stars are about 1/3 of the YSGs above 10 5 L ⊙ . We conclude that the high-luminosity YSGs with surface pulsations and circumstellar dust, distinct from other YSGs, are candidates for post-RSG evolution in the LMC.