HEAD Division Meeting 1999, April 1999
Session 9. Stellar Coronae
Poster, Monday, April 12, 1999, 8:30am-6:10pm, Gold Room

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[9.03] ASCA Spectra of the Central Star of the Orion Nebula: a Magnetic O star

M. Gagne (Rutgers), J. P. Caillault, I. Song (Georgia), Y. Tsuboi (Kyoto), J.L. Linsky (JILA), J.R. Stauffer (CfA)

The discovery of 15-day periodic H-alpha and He II emission on the central star of the Orion Nebula, theta 1 Orionis C (O7 V), suggests that this O star is an oblique magnetic rotator. The subsequent detection of large-amplitude, periodic X-ray variations led Babel and Montmerle to propose that the O star's magnetically confined wind is shocked near the magnetic equator, producing an X-ray cooling disk. In this poster, we present ASCA SIS spectra of the Trapezium obtained at rotational phases 0.01, 0.45, and 0.77. Because many unresolved T Tauri stars and OB stars produce about half the ASCA SIS flux, ROSAT HRI images obtained at similar phases and an ASCA raytrace code have been used to help reconstruct the SIS spectra. By all indications, theta 1 Ori C is a very hot source (kT > 3.0 keV). Suprisingly, we see little or no evidence of variable wind attenuation.

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