Query : 2008A&A...481..499K

2008A&A...481..499K - Astronomy and Astrophysics, volume 481, 499-506 (2008/4-2)

On the importance of the wind emission to the optical continuum of OB supergiants.


Abstract (from CDS):

Thermal wind emission in the form of free-free and free-bound emission is known to show up in the infrared and radio continuum of hot and massive stars. For OB supergiants with moderate mass loss rates and a wind velocity distribution with β≃0.8...1.0, no influence of the wind to the optical continuum, i.e. for λ≲1.0µm, is expected. Investigations of stellar and wind parameters of OB supergiants over the last few years suggest, however, that for many objects β is much higher than 1.0, reaching values up to 3.5. We investigate the influence of the free-free and free-bound emission on the emerging radiation, especially at optical wavelengths, from OB supergiants having wind velocity distributions with β≥1.0. For the case of a spherically symmetric, isothermal wind in local thermodynamical equilibrium (LTE) we calculate the free-free and free-bound processes and the emerging wind and total continuum spectra. We localize the generation region of the optical wind continuum and especially focus on the influence of a β-type wind velocity distribution with β>1 on the formation of the wind continuum at optical wavelengths. The optical wind continuum is found to be generated within about 2R* which is exactly the wind region where β strongly influences the density distribution. We find that for β>1, the continuum of a typical OB supergiant can indeed be contaminated with thermal wind emission, even at optical wavelengths. The strong increase in the optical wind emission is dominantly produced by free-bound processes.

Abstract Copyright:

Journal keyword(s): stars: early-type - stars: supergiants - stars: winds, outflows - stars: mass-loss - stars: circumstellar matter

Simbad objects: 2

goto Full paper

goto View the references in ADS

Number of rows : 2
N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
1 M 31 G 00 42 44.330 +41 16 07.50 4.86 4.36 3.44     ~ 12388 1
2 NAME Magellanic Clouds GrG 03 00 -71.0           ~ 6836 1

To bookmark this query, right click on this link: simbad:objects in 2008A&A...481..499K and select 'bookmark this link' or equivalent in the popup menu


© Université de Strasbourg/CNRS

    • Contact