SPECTROSCOPIC EUVE OBSERVATIONS OF THE ACTIVE STAR AB DORADUS

We present observations of the pre-main-sequence, rapidly rotating (0. 515 day) late-type star, AB Doradus (HD 36705), made by the Extreme Ul traviolet Explorer (EUVE) satellite. A spectrum from 80 to 700 Angstro m with a resolution Delta lambda approximate to 0.5-2 Angstrom was acc umulated between 1993 November 4-11, with an effective exposure time o f about 40 hours. No obvious EUV hares were detected during the observ ation. The data constrain the coronal temperature structure between se veral 10(4) K up to roughly 2 x 10(7) K through a differential emissio n measure analysis using the optically thin MEKA plasma model. The res ulting differential emission measure (DEM) distribution shows: (1) dom inant emission from plasma between about 2 x 10(6) and 2 x 10(7) K, wh ich may show a substructure with two components around 3 x 10(6) and 1 0(7) K; (2) very little emission from plasma between 10(5) and 2 x 10( 6) K; and (3) emission from plasma below about 10(5) K. If solar photo spheric abundances are assumed, then the formal DEM solution also requ ires the presence of a strong high-temperature component (above about 3 x 10(7) K) in order to explain the strong continuum emission below a bout 150 Angstrom. We believe that this component of the solution is n ot physical: it is not present in the solution if we assume lower iron abundance, or if there is significant resonance scattering in some of the stronger (mainly iron) spectral lines with subsequent photon abso rption in the lower, dense atmosphere. Finally, the DEM analysis gives a best-fit value for the interstellar hydrogen column density of N-H = (2.4 +/- 0.5) x 10(18) cm(-2).