X-ray emission from massive stars in CygOB2

J. F. ALBACETE COLOMBO, M. CARAMAZZA, E. FLACCOMIO, G. MICELA, & S. SCIORTINO

Lunteren - Holanda

Conferencia; Mass loss from stars and the evolution of stellar clusters; 2006

The Netherland council of research

The X-ray properties and stellar-wind parameters of 26 OBtype  stars of the CygOB2 region are examined. Absorption corrected X-rayluminosities (Lx) were calculated fitting our data with thermal emissionmodels. log(Lx)-log(Lbol) plane was constructed. Main-sequence (MS) starsare widely dispersed around the relation log(Lx/Lbol)~ -7(+-1), while evolved ones (luminosity classes I, and III) tends to follow a power-law dependence: log(Lx)~ 1.79(+-0.29) log(Lbol) - 38.2(+-11.7). We also test correlation of Lx with the quantity  W=Mdot.vinf.sqrt(R) (Modified Wind Momentum) for all OB stars of the region.