AAS 200th meeting, Albuquerque, NM, June 2002
Session 61. The Future of Extreme Ultraviolet Astronomy
Display, Wednesday, June 5, 2002, 10:00am-7:00pm, SW Exhibit Hall

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[61.04] Heating AB Dor's corona: discriminating between different loop models

G.A.J. Hussain, A.A. van Ballegooijen (Harvard-Smithsonian CfA)

We have developed a code that allows us to reconstruct realistic 3-D coronal magnetic field models for single, rapidly rotating ZAMS stars. These models are produced using an advanced version of the magnetic field mapping technique called Zeeman Doppler imaging. We compute temperatures and densities using the 3-D model obtained for the active K0V, AB Doradus (Prot=0.5d, Lx/Lbol=10-3), by solving hydrostatic equilibrium and energy balance equations along field lines. Field lines where the gas pressure exceeds the magnetic pressure are assumed to be open. These models can therefore be used to evaluate the filling factor of the corona.

Three different types of loop models that can explain the observed EUVE emission measure distribution for AB Doradus are analysed. These include: (a) very dense, compact loops (typical heights, H=0.0004R*); (b) loops with heights between 0.1-0.4R* affected by continuum absorption in the EUV; and (c) longer loops (H=0.7R*) with expanding cross-sectional areas. At present none of these models reproduce EUVE, HST and Chandra observations of AB Dor fully. We discuss what is required from future EUV observations in order to place more constraints on these models.

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Bulletin of the American Astronomical Society, 34
© 2002. The American Astronomical Soceity.