X-ray line emission from a fragmented stellar wind

Astrophysik, Institut für Physik, Universität Potsdam, Am Neuen Palais 10, 14469 Potsdam, Germany e-mail: lida, wrh@astro.physik.uni-potsdam.de

Corresponding author: A. Feldmeier, afeld@astro.physik.uni-potsdam.de

Received: 29 October 2002
Accepted: 13 February 2003

Abstract

We discuss X-ray line formation in dense O star winds. A random distribution of wind shocks is assumed to emit X-rays that are partially absorbed by cooler wind gas. The cool gas resides in highly compressed fragments oriented perpendicular to the radial flow direction. For fully opaque fragments, we find that the blueshifted part of X-ray line profiles remains flat-topped even after severe wind attenuation, whereas the red part shows a steep decline. These box-type, blueshifted profiles resemble recent Chandra observations of the O3 star ζ Pup. For partially transparent fragments, the emission lines become similar to those from a homogeneous wind.