Cool Stars 14 - Submitted Abstract # 110
This version created on 05 October 2006

Rotationally Modulated X-ray Emission from T Tauri Stars


Scott Gregory, University of St Andrews
Moira Jardine, University of St Andrews
Andrew Collier Cameron, University of St Andrews
Jean-Francois Donati,  Observatoire Midi-Pyrenees

We have modelled the rotational modulation of X-ray emission from T Tauri
stars assuming that they have isothermal, magnetically confined coronae.
By extrapolating surface magnetograms we find that T Tauri coronae are
compact and clumpy, such that rotational modulation arises from X-ray
emitting regions being eclipsed as the star rotates.  Emitting regions are
close to the stellar surface and inhomogeneously distributed about the
star.  However some regions of the stellar surface, which contain wind
bearing open field lines, are dark in X-rays.  From simulated X-ray light
curves, obtained using stellar parameters from the Chandra Orion Ultradeep
Project, we calculate X-ray periods and make comparisons with optically
determined rotation periods.  We find that X-ray periods are typically
equal to, or are half of, the optical periods.  Further, we find that
X-ray periods are dependent upon the stellar inclination, but that the
ratio of X-ray to optical period is independent of stellar mass and
radius.

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