http://arxiv.org/abs/1711.11251
The phenomenon of spectral mimicry refers to the fact that hypergiants and post-AGB supergiants – stars of different masses in fundamentally different stages of their evolution have similar optical spectra, and also share certain other characteristics (unstable and extended atmospheres, expanding gas-dust envelopes, high IR excesses). As a consequence, it is not always possible to distinguish post-AGB stars from hypergiants based on individual spectral observations in the optical range. Examples of spectral mimicry are presented using uniform, high-quality spectral material obtained on the 6-m telescope of the Special Astrophysical Observatory in the course of long-term monitoring of high-luminosity stars. It is shown that unambiguously resolving the mimicry problem for individual stars requires the determination of a whole set of parameters: luminosity, wind parameters, spectral energy distribution, spectral features, velocity field in the atmosphere and circumstellar medium, behavior of the parameters with time, and the abundances of chemical elements in the atmosphere.
V. Klochkova and E. Chentsov
Fri, 1 Dec 17
20/68
Comments: 17 pages, 7 figures, 1 table