X-ray emission from O stars
Abstract
Young O stars are strong, hard, and variable X-ray sources, properties which strongly affect their circumstellar and galactic environments. After ~1 Myr, these stars settle down to become steady sources of soft X-rays. I use high-resolution X-ray spectroscopy and MHD modeling to show that young O stars like theta-1 Ori C are well explained by the magnetically channeled wind shock scenario. After their magnetic fields dissipate, older O stars produce X-rays via shock heating in their unstable stellar winds. Here too I use X-ray spectroscopy and numerical modeling to confirm this scenario. In addition to elucidating the nature and cause of the O star X-ray emission, modeling of the high-resolution X-ray spectra of O supergiants provides strong evidence that mass-loss rates of these O stars have been overestimated.
Cite
@article{arxiv.0802.0046,
title = {X-ray emission from O stars},
author = {David H. Cohen},
journal= {arXiv preprint arXiv:0802.0046},
year = {2009}
}
Comments
9 pages; color figures. To appear in IAU Symposium 250, "Massive Stars as Cosmic Engines," Kauai, HI, December 2007; eds. Bresolin, Crowther, & Puls, Cambridge University Press, 2008. The paper posted here has one additional figure (Fig. 6). A b/w version (sans extra figure) is available at http://astro.swarthmore.edu/~cohen/papers/cohen_OstarXrays_bw_kauai2007.pdf