Comments on the Existence of Circumstellar Clouds Derived from Interstellar MG Observations
Abstract
From observations of interstellar Mg i, ii resonance lines, Gurzadyan has proposed recently that for the majority of hot stars most of the line-of-sight gas originates in dense, circumstellar clouds. To support this conclusion, which is contrary to most current models of the interstellar gas, he has set out apparently strong theoretical arguments based on empirical evidence from the sample of stars considered. In this paper we have considered the same data and have included some additional observations of interstellar Mg lines. We suggest that an empirical relationship between Mg ii equivalent width and stellar effective temperature, which is central to the model proposed by Gurzadyan, may be explained by an observational selection effect. Further, we suggest that while circumstellar material may well contribute in part to observed column densities, there is no firm evidence that most of the gas is located in circumstellar clouds.
- Publication:
-
Astrophysics and Space Science
- Pub Date:
- August 1980
- DOI:
- 10.1007/BF00646919
- Bibcode:
- 1980Ap&SS..71..211G
- Keywords:
-
- Hot Stars;
- Interstellar Gas;
- Line Spectra;
- Magnesium;
- Stellar Envelopes;
- Stellar Models;
- Gas Ionization;
- Stellar Temperature;
- Astrophysics