Astronomy and Astrophysics – Astrophysics
Scientific paper
2005-06-30
Astronomy and Astrophysics
Astrophysics
24 pages, 19 figures, accepted by A&A
Scientific paper
10.1051/0004-6361:20053522
We present the first automated fitting method for the quantitative spectroscopy of O- and early B-type stars with stellar winds. The method combines the non-LTE stellar atmosphere code FASTWIND from Puls et al. (2005) with the genetic algorithm based optimizing routine PIKAIA from Charbonneau (1995), allowing for a homogeneous analysis of upcoming large samples of early-type stars (e.g. Evans et al. 2005). In this first implementation we use continuum normalized optical hydrogen and helium lines to determine photospheric and wind parameters. We have assigned weights to these lines accounting for line blends with species not taken into account, lacking physics, and/or possible or potential problems in the model atmosphere code. We find the method to be robust, fast, and accurate. Using our method we analysed seven O-type stars in the young cluster Cyg OB2 and five other Galactic stars with high rotational velocities and/or low mass loss rates (including 10lac, zeta Oph, and tau Sco) that have been studied in detail with a previous version of FASTWIND. The fits are found to have a quality that is comparable or even better than produced by the classical ``by eye'' method. We define errorbars on the model parameters based on the maximum variations of these parameters in the models that cluster around the global optimum. Using this concept, for the investigated dataset we are able to recover mass-loss rates down to ~6d-8 Msun/yr to within an error of a factor of two. Comparison of our derived spectroscopic masses with those derived from stellar evolutionary models are in very good agreement, i.e. based on the limited sample that we have studied we do not find indications for a mass discrepancy.
de Koter Alex
Herrero Alicia
Mokiem M. R.
Najarro Francisco
Puls Jason
No associations
LandOfFree
Spectral analysis of early-type stars using a genetic algorithm based fitting method does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Spectral analysis of early-type stars using a genetic algorithm based fitting method, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Spectral analysis of early-type stars using a genetic algorithm based fitting method will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-235788