POSTER PAPER 6.08
The X-ray Corona of AB Dor
M. Jardine, K. Wood, A.C. Cameron, J.-F. Donati
Institute: Department of Physics and Astronomy, University of St
Andrews
Institute: Laboratoire dAstrophysique, Observatoire Midi-Pyrenees
Contact Email: mmj@st-andrews.ac.uk
Abstract:
We use surface magnetic maps from Zeeman-Doppler imaging to
extrapolate the coronal magnetic field of the young solar-like star AB
Dor (Prot)= 0.514 days). We assume that the coronal field is
potential and find that much of the corona is filled with open
magnetic field lines. We calculate the pressure and density within
the corona, assuming that the gas is isothermal (T=107 K) and in
hydrostatic equilibrium. Using a Monte Carlo radiative transfer code
we determine the X-ray emission measure and rotational modulation. We
find that the open field regions can cause the observed rotational
modulation of 5%-15% (Kurster et al. 1997) even for an optically
thin corona that extends to over 3Rstar. The corona is highly
structured with a low filling factor (0.1% to 1%). By varying the
base density, we find that densities in excess of 1010 cm-3
are needed to explain the observed emission measures of
1052 -- 1053 cm-3 (Vilhu et al. 2001).
Index Keywords: AB Dor; Doppler Imaging; MHD; Corona
Previous: Messina
Up: Poster Index
Up: Top Index
Manuscript submitted: 2001-Sep-06
"The Future of Cool-Star Astrophysics", 2003, Eds. A. Brown,
G. M. Harper, & T. R. Ayres.
Proceedings of 12th Cambridge Workshop on Cool Stars, Stellar Systems,
& The Sun,
© 2003 University of Colorado.