Abstract

We present ASCA and ROSAT X-ray observations of the classical T Tauri star TW Hya, the namesake of a small association that, at a distance of ~50 pc, represents the nearest known region of recent star formation. Analysis of ASCA and ROSAT spectra indicates characteristic temperatures of ~1.7 and ~9.7 MK for the X-ray emitting region(s) of TW Hya, with emission lines of highly ionized Fe dominating the spectrum at energies of ~1 keV. The X-ray data show variations in X-ray flux on timescales of ~<1 hr as well as indications of changes in the X-ray absorbing column on timescales of several years, suggesting that flares and variable obscuration are responsible for the large-amplitude optical variability of TW Hya on short and long timescales, respectively. Comparison with model calculations suggests that TW Hya produces sufficient hard X-ray flux to produce significant ionization of molecular gas within its circumstellar disk; such X-ray ionization may regulate both protoplanetary accretion and protoplanetary chemistry (Refer to PDF file for exact formulas).

Publication Date

11-10-1999

Comments

Also archived in: arXiv: astro-ph/9905126 v2 25 May 1999 Primary support for this work was provided by NASA ASCA data analysis grant NAG 5-4959 to Massachusetts Institute of Technology. Research by J. H. K., D. P. H., and N. S. S. at Massachusetts Institute of Technology is also supported by the Chandra X-ray Observatory Science Center as part of Smithsonian Astrophysical Observatory contract SVI-61010 under NASA Marshall Space Flight Center. Support for research by D. A. W. and J. H. K. was also provided by NASA Origins of Solar Systems program grant NAG 5-8295 to Vanderbilt University.ISSN:1538-4365 Note: imported from RIT’s Digital Media Library running on DSpace to RIT Scholar Works in February 2014.

Document Type

Article

Department, Program, or Center

Chester F. Carlson Center for Imaging Science (COS)

Campus

RIT – Main Campus

Share

COinS