The luminosity of the famous red supergiant VY CMa (L ~ 4 - 5 x 10e5 Lsun) is well-determined from its spectral energy distribution and distance, and places it near the empirical upper luminosity limit for cool hypergiants. In contrast, its surface temperature is fundamentally ill-defined. Both contradict a recent paper by Massey, Levesque and Plez (2006). Implications for its location on the HR Diagram and its apparent size are discussed.
@article{arxiv.astro-ph/0610433,
title = {VY Canis Majoris: The Astrophysical Basis of Its Luminosity},
author = {Roberta M. Humphreys},
journal= {arXiv preprint arXiv:astro-ph/0610433},
year = {2007}
}