2007PASJ...59..237Y

begin{HTML}We analyzed the X-ray emission-line profiles of three early-type stars (z Pup, d Ori, and t Sco) obtained with Chandra. A phenomenological model, where X-ray sources are distributing in wind above some lower limit radius, can fit the line profiles of z Pup and d Ori; however, the fitting requires a much smaller absorption than expected from the mass-loss rate. This suggests that, if this phenomenological model represents the real X-ray emission region, there is substantial ionization or clumping of the stellar wind. The parameters derived from the line profile of t Sco indicate that the X-ray-emitting plasma is concentrated on the stellar surface, suggesting the existence of a confined plasma on the stellar surface.