AAS 196th Meeting, June 2000
Session 5. Be Star and Other Atmosphere Studies
Display, Monday, June 5, 2000, 9:20am-6:30pm, Empire Hall South

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[5.14] Observations of Magnetically Active Binary Stars using Phoenix

D. O'Neal (West Liberty State College), J. K. Mines (Washington and Jefferson College), J. E. Neff (College of Charleston), S. H. Saar (CfA)

We present observations of several magnetically-active, post-main sequence binary systems (all of the RS~CVn class) obtained with the NOAO Phoenix Infrared Spectrograph. Our high-resolution spectra are centered on the 6397cm-1 (1.563\mum) lines of OH. These lines are temperature-sensitive and thus are a good diagnostic of the area coverage of dark, cool starspots on the stars (O'Neal and Neff 1997). Our new observations, using Phoenix, are of higher resolution and greater signal-to-noise than those we presented previously.

By modeling the active stars as the sum of an inactive comparison star (to represent the active star's photosphere)and an M star (to represent the spots), we measure starspot filling factors on II~Peg, V1762~Cyg, \sigma~Gem, and \lambda~And. We find filling factors similar to those we previously measured for the same stars using TiO bands. We also (for the first time) fit the spectra of double-lined binary stars with this technique, enabling us to determine the level of starspot coverage on the active components. Our spectra also contain the highly Zeeman-sensitive (g=3) Fe~I~6388cm-1 line; analysis of this feature enables us to measure the mean field strength and area filling factor of the magnetic regions of the active stars. In the future we will apply Doppler imaging techniques, adapted to our H-band spectra, to our observations in order to derive images of the starspot distributions.

The authors were guest observers at Kitt Peak National Observatory, National Optical Astronomy Observatories.

The author(s) of this abstract have provided an email address for comments about the abstract: onealdb@wlsc.wvnet.edu

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