Measuring mass-loss rates and constraining shock physics using X-ray line profiles of O stars from the Chandra archive

摘要: We quantitatively investigate the extent of wind absorption signatures in X-ray grating spectra all non-magnetic, effectively single O stars Chandra archive via line profile fitting. Under usual assumption a spherically symmetric with embedded shocks, we confirm previous claims that some objects show little or no absorption. However, many other do asymmetric and blueshifted profiles, indicative For these stars, are able to derive mass-loss rates from ensemble find values lower by an average factor 3 than those predicted current theoretical models, consistent Hα if clumping factors fcl ≈ 20 assumed. The same fitting indicates onset radius X-rays typically at r 1.5R*, terminal velocities for emitting component bulk wind. explore likelihood sample not significant their profiles have least emission arises colliding shocks close binary companion. one clear exception is ζ Oph, weak-wind star appears simply very low rate. also reanalyse results canonical supergiant Pup, using solar-metallicity opacity model M^˙=1.8×10−6 M_ ⊙yr^−1, recent multiwavelength determinations.