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Astronomy and Astrophysics

HD 152248: evidence for a colliding wind interaction+

H. Sana1, G. Rauw1,* and E. Gosset1,**

1 Institut d'Astrophysique et de Géophysique - Université de Liège, Avenue de Cointe 5, 4000 Liège, Belgium

* Postdoctoral Researcher FNRS, Belgium
** Research Associate FNRS, Belgium

+ Based on observations collected at the European Southern Observatory (La Silla, Chile) and at the Cerro Tololo Inter-American Observatory (CTIO)


     We present the results of a four year spectroscopic campaign on the early-type binary system HD 152248. Our analysis yields a new classification as O7.5III(f) + O7III(f) in contradiction with previous classifications of the components as supergiants. We derive improved orbital elements and the corresponding masses M1=29.6 M and M2=29.9 M are somewhat larger than previously reported in the literature, though they are still significantly lower than the ones expected from evolutionary tracks. Both components of the system are rather close to fill their Roche lobe at periastron passage. We also investigate the equivalent width variations of the lines of the two components and we discuss their relation to the Struve-Sahade effect. Finally, we show that the line profile variability of the HeII 4686 and H lines is consistent with a strong wind interaction between the two stars very much as predicted by current colliding wind models.

Key Words
binaries: close -- binaries: spectroscopic -- Stars: early-type -- Stars: fundamental parameters -- Stars individual: HD 152248 -- Stars: winds, outflows

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