Free access article

Issue A&A Volume 413, Number 2, January II 2004 Page(s) 693 - 709 Section Formation and evolution of planetary systems DOI 10.1051/0004-6361:20031463

A&A 413, 693-709 (2004)
DOI: 10.1051/0004-6361:20031463

Bright OB stars in the Galaxy

I. Mass-loss and wind-momentum rates of O-type stars: A pure H analysis accounting for line-blanketing

N. Markova¹, J. Puls², T. Repolust² and H. Markov<sup>1

1</sup>  Institute of Astronomy and Isaac Newton Institute of Chile Bulgarian Branch, Bulgarian National Astronomical Observatory, PO Box 136, 4700 Smoljan, Bulgaria
    e-mail: rozhen@mbox.digsys.bg
²  Universitäts-Sternwarte München, Scheinerstrasse 1, 81679 Munchen, Germany

(Received 20 December 2002 / Accepted 11 September 2003)

Abstract
We study mass-loss and wind momentum rates of 29 Galactic O-type stars with luminosity classes I, III and V by means of a pure H profile analysis and investigate to what extent the results compare to those originating from a state-of-the-art, complete spectral analysis. Our investigation relies on the approximate method developed by Puls et al. (1996) which we have modified to account for the effects of line-blanketing. Effective temperatures and gravities needed to obtain quantitative results from such a simplified approach have been derived by means of calibrations based on most recent spectroscopic NLTE analyses and models of Galactic stars by Repolust et al. (2003) and Martins et al. (2002). Comparing (i) the derived wind-densities to those determined by Repolust et al. (2003) for eleven stars in common and (ii) the Wind-momentum Luminosity Relationship (WLR) for our sample stars to those derived by other investigations, we conclude that our approximate approach is actually able to provide consistent results. Additionally, we studied the consequences of "fine tuning" some of the direct and indirect parameters entering the WLR, especially by accounting for different possible values of stellar reddening and distances. Combining our data set with the corresponding data provided by Herrero et al. (2002) and Repolust et al. (2003) we finally study the WLR for the largest sample of Galactic O-type stars gathered so far, including an elaborate error treatment. The established disagreement between the theoretical predictions and the "observed" WLRs being a function of luminosity class is suggested to be a result of wind clumping. Different strategies to check this hypothesis are discussed, particularly by comparing the H mass-loss rates with the ones derived from radio observations.

Key words: stars: early-type -- stars: mass-loss -- stars: winds, outflows -- stars: distances -- stars: fundamental parameters

Offprint request: N. Markova, markova@usm.uni-muenchen.de

SIMBAD Objects in preparation

© ESO 2004

What is OpenURL?