AAS 202nd Meeting, May 2003
Session 32 Stellar Atmospheres and Circumstellar Material
Poster, Tuesday, May 27, 2003, 10:00am-6:30pm, West Exhbit Hall

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[32.07] Measurements of Activity in 1000 Planet Search Stars

J. T. Wright, G. M. Marcy, D. A. Fischer (UC Berkeley), R. P. Butler (Carnegie Institute of Washington, DTM)

The California & Carnegie Planet Search Program has been regularly observing several hundred late-type main-sequence stars at high spectral resolution as the core of its ongoing survey of bright stars to find extrasolar planets through precision radial velocity measurements. One source of error in the measured velocities is that due to ``photospheric jitter'': flows and inhomogeneities on the stellar surface can produce variations in the measured radial velocity of a star and can even mimic the signature of planetary companions. Fortunately, in addition to providing a precision radial velocity, each observation provides a measurement of the strength of the stellar chromospheric Calcium II H & K emission cores. These measurements are a standard metric of stellar activity which can provide an estimate of the photospheric jitter and rotation period of a star, both critical values for understanding and interpreting the noise present in radial velocity measurements. Here, we present our calculated activity levels, expressed as Mt. Wilson S values, and derived rotation periods for about 1000 stars in the planet search program from the Keck telescope.

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Bulletin of the American Astronomical Society, 35 #3
© 2003. The American Astronomical Soceity.