2013/05/26 by Roberta M. Humphreys, R. M. Humphreys, Kris Davidson +8 · 67 citations
Physics and Astronomy · #Astronomy #Astronomy and Astrophysical Research #Astrophysics #Gamma-ray bursts and supernovae #Physics #Red giant #Red supergiant #Solar mass #Stars #Stellar, planetary, and galactic studies #Supergiant #Supernova #astro-ph.SR
paper · pdf · doi:10.1088/0004-637x/773/1/46
published in The Astrophysical Journal 773(1), 46 (IOP Publishing) · To appear in the Astrophysical Journal
arxiv created 2013/05/26 · openalex publication_date 2013/07/24 · arxiv updated 2015/06/16 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/06
The progenitors of Type IIP supernovae (SNe) have an apparent upper limit to their initial masses of about 20 M ☉ , suggesting that the most massive red supergiants evolve to warmer temperatures before their terminal explosion. But very few post-red supergiants are known. We have identified a small group of luminous stars in M31 and M33 that are candidates for post-red supergiant evolution. These stars have A–F-type supergiant absorption line spectra and strong hydrogen emission. Their spectra are also distinguished by the Ca ii triplet and [Ca ii ] doublet in emission formed in a low-density circumstellar environment. They all have significant near- and mid-infrared excess radiation due to free–free emission and thermal emission from dust. We estimate the amount of mass they have shed and discuss their wind parameters and mass loss rates, which range from a few × 10 −6 to 10 −4 M ☉ yr −1 . On an H-R diagram, these stars will overlap the region of the luminous blue variables (LBVs) at maximum light; however, the warm hypergiants are not LBVs. Their non-spherical winds are not optically thick, and they have not exhibited any significant variability. We suggest, however, that the warm hypergiants may be the progenitors of the "less luminous" LBVs such as R71 and even SN1987A.