Luminous variable stars in M31 and M33

Journal Article · Sun Jan 15 04:00:00 EST 1978 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/155797· OSTI ID:6502266

Humphreys, R M

Spectra and UBVRI photometry of eight luminous blue variables in M31 and M33 reveal the presence of both ultraviolet and infrared excess radiation. These supergiants, including four Hubble--Sandage variables, have spectra characterized by a strong ultraviolet continuum, no apparent Balmer discontinuity, and emission lines of H, He I, Fe II, and (Fe II). They have very low surface gravities combined with large radiated fluxes. Their luminosities are typically near low surface gravities combined with large radiated fluxes. Their luminosities are typically near -10 mag (m/sub ..nu..) at maximum light. AF And in M31 was measured at 2..mu.. and is the most distant single star yet observed at long wavelengths. In addition, a red variable in M31 as classified as an M supergiant with M/sub ..nu../ approx. -7.2 mag at maximum. The hot, very luminous supergiants are spectroscopically and photometrically similar to eta Car and S Dor and related objects in our Galaxy and the LMC. Together they form a recognizable group of luminous blue stars in four separate galaxies in the Local Group. 4 figures, 4 tables.

• Research Organization: Univ. of Minnesota, Minneapolis
• OSTI ID: 6502266
• Journal Information: Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 219:2; ISSN ASJOA
• 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
EMISSION SPECTRA
GALAXIES
GIANT STARS
GRAVITATIONAL FIELDS
LUMINOSITY
OPTICAL PROPERTIES
PHOTOMETRY
PHYSICAL PROPERTIES
SPECTRA
STARS
SUPERGIANT STARS
VARIABLE STARS