ASCA X-RAY-SPECTRA OF THE ACTIVE SINGLE STARS BETA-CETI AND PI(1)-URSAE-MAJORIS

We present X-ray spectra obtained by ASCA of two single, active stars, the G dwarf pi(1) UMa, and the G9/KO giant beta Cet. The spectra of b oth stars require the presence of at least two plasma components with different temperatures, 0.3-0.4 keV and similar to 0.7 keV, in order f or acceptable fits to be obtained. The spectral resolving power and si gnal-to-noise ratio of the SIS spectra allow us to formally constrain the coronal abundances of a number of elements. In beta Cet, we find M g to be overabundant, while other elements such as O, Ne, and N are un derabundant, relative to the solar photospheric values. From the lower signal-to-noise ratio SIS spectrum of pi(1) UMa, we find evidence for underabundances of O, Ne, and Fe. These results are discussed in the context of the present understanding of elemental abundances in solar and stellar coronae.