Jardine, Moira

Contact Email: mmj@st-andrews.ac.uk
Institute: Department of Physics and Astronomy, North
Haugh, St Andrews, Fife, KY16 9SS Scotland
First Coauthor: K. Wood
Institute: Department of Physics and Astronomy, North
Haugh, St Andrews, Fife, KY16 9SS Scotland
Second Coauthor: A.C. Cameron
Institute: Department of Physics and Astronomy, North
Haugh, St Andrews, Fife, KY16 9SS Scotland
Research URL:http://star-www.st-and.ac.uk/~mmj/
Subject Area: Single Stars
Waveband: X-rays
Technique: Imaging (Doppler)
Presentation: Poster Display
Title: The X-ray Corona of AB Dor
Abstract: Young solar-like stars are known to much more luminous than the Sun in X-rays. It is not clear however if this emission is enhanced because the corona is more extended, or more dense. The large emission measures and small rotational modulation suggest extremely large loop volumes containing the X-ray emitting gas. Calculations of plasma densities, however, suggest that the emission comes from small, compact regions close to the stellar surface, perhaps at sufficiently high latitudes to explain the lack of rotational self-eclipse. We present here a study of the nature of the X-ray emitting structures on the young K0 dwarf AB Dor (rotation period 0.5 days). We begin with maps of the surface magnetic field vectors acquired using Zeeman-Doppler imaging. We extrapolate the coronal magnetic field assuming it to be potential and then calculate the coronal density and emission measure for an isothermal gas in hydrostatic equilibrium. Large parts of the corona are dark in X-rays because the magnetic field lines are open. As a result, the observed 5 be obtained even with a corona that extends to several stellar radii.