Статья

Evidence for Accretion: High‐Resolution X‐Ray Spectroscopy of the Classical T Tauri Star TW Hydrae

Joel H. KastnerChester F. Carlson Center for Imaging Science, Rochester Institute of Technology, 54 Lomb Memorial Drive, Rochester, NY 14623David P. HuenemoerderMassachusetts Institute of Technology, Center for Space Research, 70 Vassar Street, Cambridge, MA 02139Norbert S. SchulzMassachusetts Institute of Technology, Center for Space Research, 70 Vassar Street, Cambridge, MA 02139C. R. CanizaresMassachusetts Institute of Technology, Center for Space Research, 70 Vassar Street, Cambridge, MA 02139David A. WeintraubDepartment of Physics and Astronomy, Vanderbilt University, Nashville, TN 37235

2002en

ABI

Аннотация

We present high resolution X-ray spectra of the X-ray bright classical T Tauri star, TW Hydrae, covering the wavelength range of 1.5-25 °A. The differential emission measure derived from fluxes of temperature-sensitive emission lines shows a plasma with a sharply peaked temperature distribution, peaking at log T = 6.5. Abundance anomalies are apparent, with iron very deficient relative to oxygen, while neon is enhanced relative to oxygen. Density-sensitive line ratios of Ne ix and O vii indicate densities near (log ne)=13. A flare with rapid (~1 ks) rise time was detected during our 48 ksec observation; however, based on analysis of the emission-line spectrum during quiescent and flaring states, the derived plasma parameters do not appear strongly time-dependent. The inferred plasma temperature distribution and densities are consistent with a model in which the bulk of the X-ray emission from TW Hya is generated via mass accretion from its circumstellar disk. Assuming accretion powers the X-ray emission, our results for (log ne) suggest an accretion rate of ~10^−8M⊙ yr^−1 (Refer to PDF file for exact formulas).

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Идентификаторы

DOI: 10.1086/338419

Цитирования и источники

Цитирований: 2Использованных источников: 0

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