AAS Meeting #193 - Austin, Texas, January 1999
Session 45. Spectral Observations of Stars
Display, Thursday, January 7, 1999, 9:20am-6:30pm, Exhibits Hall 1

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[45.10] HST/STIS Echelle Spectra of the dM0e Star AU Mic Outside of Flares

J.L. Linsky (JILA), R.D. Robinson (IACS/CUA), L. Carkner (JILA), B. Woodgate (GSFC/NASA), G. Timothy (Nightsen Inc.)

We report on observations of the dM0e flare star AU Microscopii (HD197481) obtained with the Space Telescope Imaging Spectrograph (STIS) on 1998 Sept 6. We analyze 10105 seconds of observations obtained with the medium resolution E140M grating, which covers the complete 1170--1730 Å\ spectral range with a resolution of 45,800 (corresponding to 6.6 km/s). The data were obtained in the TIME-TAG mode to isolate time intervals of flaring. We report here on the 9200 seconds of data for which the star did not have a large flare.

In this beautiful data set we identify more than 70 emission lines including low temperature chromospheric lines (e.g., C~I, O~I), transition region lines (e.g., C~II--IV, N~IV, O~III-V, Si~II-IV), and the coronal line Fe~XXI 1354 Å. There are a number of intersystem lines that are useful for measuring electron densities. We discuss line redshifts and the broad wings of transition region lines that provide evidence of microflare heating. We also discuss the shapes of the Lyman-\alpha and He~II 1640~Å\ lines, and the interstellar absorption features seen in the H~I, D~I, C~II, and Mg~II resonance lines.

This work is supported by NASA grants to the University of Colorado and the Catholic University of America.

The author(s) of this abstract have provided an email address for comments about the abstract: jlinsky@jila.colorado.edu

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