Temperatures and radii of O stars

Abstract

Angular diameters have been estimated for 18 O and 142 B stars using absolute intermediate-band photometry in the near infrared and they have been combined with integrated fluxes to yield effective temperatures. The effective temperatures of the O stars lie in the range 30000 K to about 47000 K. For a given subtype, the luminosity class I stars have lower effective temperatures than the main-sequence stars by about 1000 K. The absorption-line spectral types of the supergiants of types O and B reflect electron temperatures which are higher than can be maintained by the integrated flux which flows through the stellar atmosphere. Distances have been estimated for all the stars and linear diameters found. The average radius for an 08 to 09.5 supergiant is about 23.3 R⊙; the radii for luminosity class III and Class V O stars lie in the range 6.8 to 10.7⊙ R.

MV and Teff of B-Type Stars as Derived from 13-Color Photometry

“…Figs. 1 and 2 show the correlations between the values of Underhill et al (1979;UDPD) and ours (CM) for T eff anc * M V res P ective ly* Tne rms residual is 0.017 for log T e f f and 0.287 for M v .…”

“…We begin with B type stars as there is an excellent paper of Underhill et al (1979) which evaluates many physical quantities for 160 0-B type stars which are among the stars observed in the 13 color system. The present paper describes the procedure we adopted to get preliminary relations for deriving T e ff's and My's.…”

Model Atmospheres and Radiative Transfer in Chemically Peculiar Stars: Interpretational Significance of Non-LTE

“…Systematic studies of a sample of stars have been carried out, e.g. by Underhill et al (1979), Bohm-Vitense (1981), and Malagnini et al (1982. Generally, these authors have demonstrated that Kurucz's models reproduce the observed visual distribution fairly well, while the UV flux is reproduced somewhat worse, but still satisfactorily.…”

The evolution of massive stars; an observational viewpoint

“…Work is still hampered by uncertainty in the exact shape of the interstellar extinction curve, (Seaton, 1979) and uncertainties in the stellar model atmospheres (Kurucz, 1979). Underhill et al (1979) have conducted a careful survey of hot star continuum intensity data, and derived temperatures and luminosities. Their findings indicate a lower temperature for higher luminosity stars of a given spectral type, in general agreement with earlier indications (e.g.…”