DETAILED X-RAY LINE PROPERTIES OF θ[superscript 2] Ori A IN QUIESCENCE
Author(s)
Mitschang, Arik W.; Schulz, Norbert S.; Huenemoerder, David P.; Nichols, Joy S.; Testa, Paola; Huenemoerder, David P.; ... Show more Show less
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Alternative title
DETAILED X-RAY LINE PROPERTIES OF θ2 Ori A IN QUIESCENCE
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We investigate X-ray emission properties of the peculiar X-ray source θ[superscript 2] Ori A in the Orion Trapezium region using more than 500 ks of HETGS spectral data in the quiescent state. The amount of exposure provides tight constraints on several important diagnostics involving O, Ne, Mg, and Si line flux ratios from He-like ion triplets, resonance line ratios of the H- and He-like lines, and line widths. Accounting for the influence of the strong UV radiation field of the O9.5V star, we can now place the He-like line origin well within two stellar radii of the O-star's surface. The lines are resolved with average line widths of 341 ± 38 km s[superscript –1]. In the framework of standard wind models, this likely implies a rather weak wind with moderate post-shock velocities. The emission measure distribution of the X-ray spectrum, as reported previously, includes very high temperature components which are not easily explained in this framework. The X-ray properties are also not consistent with coronal emissions from an unseen low-mass companion nor with typical signatures from colliding wind interactions. The properties are more consistent with X-ray signatures observed in the massive Trapezium star θ[superscript 1] Ori C which has recently been successfully modeled with a magnetically confined wind model.
Date issued
2011-06Department
MIT Kavli Institute for Astrophysics and Space ResearchJournal
Astrophysical Journal
Publisher
Institute of Physics/American Astronomical Society
Citation
Mitschang, Arik W., Norbert S. Schulz, David P. Huenemoerder, Joy S. Nichols, and Paola Testa. “ DETAILED X-RAY LINE PROPERTIES OF θ[superscript 2] Ori A IN QUIESCENCE .” The Astrophysical Journal 734, no. 1 (May 20, 2011): 14. © 2011 American Astronomical Society.
Version: Final published version
ISSN
0004-637X
1538-4357