The circumstellar shells and mass loss rates of four M supergiants

Abstract

view Abstract Citations (93) References (34) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The circumstellar shells and mass loss rates of four M supergiants. Bernat, A. P. Abstract A reanalysis of the physical structure of the circumstellar gas shells of four bright M super- giants, Betelgeuse, Antares, a Herculis, and Cephei, has been undertaken. The observational data include old Hale Observatories plates, recent McDonald Struve telescope plates, and McDonald 2.7 m photoelectric scans. These data are analyzed in the full expanding spherical geometry formulation of the radiative transfer equation. The results of the present analysis indicate that column densities in the gas shells must be revised downward compared with the previous plane-parallel results. However, the physical extents of the shells are considerably larger than previously assumed. These extents are inferred through ionization modeling, Weymann's Ca ii technique, and direct observation. Also inferred are schematic wavelength-dependent chromospheric color temperatures. These results lead to much larger mass loss rates (in the range 6.7 x l0- to 4.2 x 10- M0 yr-2) than previously inferred. The influence of these large rates of mass loss on the evolution of both stars and the Galaxy is briefly discussed. Subject headings: stars: circumstellar shells - stars: mass loss - stars: supergiants Publication: The Astrophysical Journal Pub Date: May 1977 DOI: 10.1086/155205 Bibcode: 1977ApJ...213..756B Keywords: M Stars; Mass Transfer; Radiative Transfer; Stellar Envelopes; Stellar Models; Supergiant Stars; Abundance; Chromosphere; Gas Ionization; Photoionization; Stellar Atmospheres; Stellar Evolution; Stellar Spectrophotometry; Astrophysics full text sources ADS |