New Challenges For Wind Shock Models: The Chandra Spectrum Of The Hot Star Delta Orionis

Authors

N. A. Miller
J. P. CassinelliFollow
W. L. WaldronFollow
J. J. MacFarlaneFollow
David H. Cohen, Swarthmore CollegeFollow

Document Type

Article

Publication Date

10-1-2002

Published In

Astrophysical Journal

Abstract

The Chandra spectrum of delta Ori A shows emission lines from hydrogen- and helium-like states of Si, Mg, Ne, and O, along with N VII Lyalpha and lines from ions in the range Fe XVII-Fe XXI In contrast to the broad lines seen in zeta Pup and zeta Ori (850 +/- 40 and 1000 +/- 240 km s(-1) half-width at half-maximum [HWHM], respectively), these lines are broadened to only 430 +/- 60 km s(-1) HWHM. This is much lower than the measured wind terminal velocity of 2000 km s(-1). The forbidden, intercombination, and resonance (fir) lines from He-like ions indicate that the majority of the X-ray line emission does not originate at the base of the wind, in agreement with the standard wind shock models for these objects. However, in that model the X-ray emission is distributed throughout an expanding, X-ray-absorbing wind, and it is therefore surprising that the emission lines appear relatively narrow, unshifted, and symmetric. We compare the observed line profiles to recent detailed models for X-ray line pro le generation in hot stars, but none of them offers a fully satisfactory explanation for the observed line profiles.

Comments

This work is freely available courtesy of IOP Publishing and the American Astronomical Society.

Recommended Citation

N. A. Miller et al. (2002). "New Challenges For Wind Shock Models: The Chandra Spectrum Of The Hot Star Delta Orionis". Astrophysical Journal. Volume 577, Issue 2. 951-960. DOI: 10.1086/342111
https://works.swarthmore.edu/fac-physics/18