• DOI:10.1086/367553
• Corpus ID: 1062231

High-Resolution Chandra Spectroscopy of τ Scorpii: A Narrow-Line X-Ray Spectrum from a Hot Star

@article{Cohen2003HighResolutionCS,
  title={High-Resolution Chandra Spectroscopy of $\tau$ Scorpii: A Narrow-Line X-Ray Spectrum from a Hot Star},
  author={David H Cohen and Genevi{\`e}ve E. de Messi{\`e}res and J. J. Macfarlane and Nathan A. Miller and Joseph Patrick Cassinelli and Stanley P. Owocki and Duane A. Liedahl},
  journal={The Astrophysical Journal},
  year={2003},
  volume={586},
  pages={495-505}
}

• D. Cohen, G. D. Messières, +4 authors D. Liedahl
• Published 18 November 2002
• Physics
• The Astrophysical Journal

Long known to be an unusual early-type star by virtue of its hard and strong X-ray emission, τ Scorpii poses a severe challenge to the standard picture of O-star wind-shock X-ray emission. The Chandra HETGS spectrum now provides significant direct evidence that this B0.2 star does not fit this standard wind-shock framework. The many emission lines detected with the Chandra gratings are significantly narrower than what would be expected from a star with the known wind properties of τ Sco, although they are broader than the corresponding lines seen in late-type coronal sources. While line ratios are consistent with the hot plasma on this star being within a few stellar radii of the photosphere, from at least one He-like complex there is evidence that the X-ray-emitting plasma is located more than a stellar radius above the photosphere. The Chandra spectrum of τ Sco is harder and more variable than those of other hot stars, with the exception of the young magnetized O star θ1 Ori C. We discuss these new results in the context of wind, coronal, and hybrid wind-magnetic models of hot-star X-ray emission.