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Spectroscopic EUVE Observations of the Active Star AB Doradus

Published online by Cambridge University Press:  12 April 2016

Slavek M. Rucinski ,
Rolf Mewe ,
Jelle S. Kaastra ,
Osmi Vilhu  and
Stephen M. White
Slavek M. Rucinski
Affiliation:
Institute for Space and Terrestrial Science and York University, 4850 Keele St., Toronto, Ontario, M3J 3K1, Canada
Rolf Mewe
Affiliation:
Space Research Organization Netherlands (SRON), Sorbonnelaan 2, NL 3584 CA Utrecht, The Netherlands
Jelle S. Kaastra
Affiliation:
Space Research Organization Netherlands (SRON), Sorbonnelaan 2, NL 3584 CA Utrecht, The Netherlands
Osmi Vilhu
Affiliation:
Observatory and Astrophysics Laboratory, Box 14, FIN-00014, University of Helsinki, Finland
Stephen M. White
Affiliation:
Department of Astronomy, University of Maryland, College Park, MD 20742, USA

Abstract

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We present observations of the pre-Main Sequence, rapidly-rotating (0.515 day) late-type star, AB Doradus (HD 36705), made by the Extreme Ultraviolet Explorer (EUVE) satellite. A high-quality spectrum was accumulated between November 4-11, 1993, with an effective exposure time of about 40 hours. The data constrain the coronal temperature structure between several 104 K up to roughly 2 × 107 K through a differential emission measure analysis using an optically-thin plasma model. The resulting differential emission measure (DEM) distribution shows: a) dominant emission from plasma between about 2 × 106 K and 2 × 107 K, b) very little emission from plasma between 105 K and 2 × 106 K, and c) emission from plasma below about 105 K. If solar photospheric abundances are assumed, then the formal DEM solution also requires the presence of a strong high-temperature component (above about 3 × 107 K) in order to fit the strong continuum emission below about 150 Å; however, we believe that this component of the solution is not physical. The DEM analysis gives a best-fit value for the interstellar hydrogen column density of NH = (2.4 ± 0.5) × 1018 cm−2.

Type
III. Coronae of Cool Stars
Information
International Astronomical Union Colloquium , Volume 152: Astrophysics in the Extreme Ultraviolet , 1996 , pp. 159 - 164
Copyright
Copyright © Kluwer 1996

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