AAS 197, January 2001
Session 11. Extrasolar Planets and Very Low Mass Stars
Display, Monday, January 8, 2001, 9:30am-7:00pm, Exhibit Hall

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[11.07] Effects of Stellar Magnetic Activity on High Resolution Line Profiles and Radial Velocity Measurements.

N.S. Pearson (Bowling Green State University), S.H. Saar (SAO), A.P. Hatzes (U. Tautenburg), D. Paulsen (U. Texas, Austin)

We study very high resolution (\lambda/\Delta \lambda \approx 200,000), high S/N (350 - 550) echelle spectra of five G to early K type stars (\beta Com, \epsilon Eri, 61 UMa, 59 Vir, and \xi Boo A) and construct bisectors for ~30 unblended Fe I absorption lines in each. We collate the bisectors into subgroups based upon absorption line depth and excitation potential, calculate many statistical measures of the bisector position and shape, and average these measurements over the subgroups. We then search for relationships between the averaged bisector properties and various stellar properties, such as temperature, activity and v\ sin\ i; several significant trends are found. We investigate how the bisectors change over time with relation to stellar properties in an effort to find trends between the bisector properties, stellar magnetic surface features, and apparent radial velocity (\textit{v}r). Such correlations would allow for the correction of some of the scatter in measurements of the \textit{v}r, permitting easier detection of sub-jovian exoplanets. We find changes in certain bisector measures to be well correlated with \textit{v}r changes.

This work was supported by National Science Foundation grant AST-9731652.

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