Circumstellar gas and dust shells of M Giants and Supergiants

Journal Article · Fri Sep 01 04:00:00 EDT 1978 · Astrophys. J., Suppl. Ser.; (United States)

DOI:https://doi.org/10.1086/190542· OSTI ID:6536202

Hagen, W

Optical and infrared observations are combined to study the circumstellar (CS) envelopes of late-type giants and supergiants. Coude spectrograms at 6.7 A mm/sup -1/ and echellograms at 5.1 A mm/sup -1/ were obtained to observe violet-displaced CS line cores. The solution of the equation of transfer in an expanding, extended atmosphere is used to derive the column density of CS matter from the observed line asymmetries. Infrared fluxes are presented from new infrared photometry, and infrared photometry and spectrophotometry from the literature. The predicted energy distributions from model dust shells including the effects of self-absorption by dust are used to derive the column densities of CS dust from the observed height of the 10 ..mu..m silicate feature.Comparison of the derived amounts of CS gas and dust reveals a large variation in the gas-to-dust ratio from star to star, with the metals in the stars of spectral type M6 and later appearing almost entirely as grains. The inner radii of the envelopes are not well determined; the observed shells probably lie outside an extended turbulent region above the photosphere. Particle densities at the inner shell radii range from 10/sup 7/ to 10/sup 8/ cm/sup -3/. Mass loss rates range from 10/sup -8/ to 10/sup -6/ Msun yr/sup -1/ and are shown to be relatively insensitive to the gas-to-dust ratio, indicating that the mechanism of mass loss may be something other than radiation pressure on dust grains.

• Research Organization: Institute for Astronomy, University of Hawaii
• OSTI ID: 6536202
• Journal Information: Astrophys. J., Suppl. Ser.; (United States), Journal Name: Astrophys. J., Suppl. Ser.; (United States) Vol. 38:1; ISSN APJSA
• Country of Publication: United States
• Language: English

Related Subjects

640102* -- Astrophysics & Cosmology-- Stars & Quasi-Stellar
Radio & X-Ray Sources
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
COSMIC DUST
DUSTS
GIANT STARS
INFRARED SPECTRA
INTERSTELLAR GRAINS
MASS TRANSFER
PARTICLES
PHOTOMETRY
RED GIANT STARS
SPECTRA
STARS
SUPERGIANT STARS