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D. S. Mitchell (UC, San Diego), S. Frink, A. Quirrenbach (Sterrewacht Leiden), D. A. Fischer (SFSU), G. W. Marcy (UC, Berkeley), R. P. Butler (Carnegie Institution of Washington)
We report the detection of sub-stellar companion candidates around four nearby K giant stars. These objects were detected using precise radial velocity measurements taken with the Hamilton echelle spectrograph at Lick Observatory as a part of our survey of 182 K giants. Two of the companions have minimum masses in the planetary regime, while the other two companions appear to be brown dwarfs.
HD 59686 harbors a companion with a minimum mass of 6.5 jupiter masses and an orbital period of 303 days. 91 Aqr has a companion with a minimum mass of 2.9 jupiter masses, and an orbital period of 182 days. The companion orbiting tau Gem has a minimum mass of 18.1 jupiter masses, and a period of 305 days. nu Oph harbors a companion with a minimum mass of 21.9 jupiter masses and an orbital period of 536 days.
Observations of these stars were taken using the iodine cell technique, and had typical radial velocity precision of 5 m/s. Observations of HD 59686 began in June 1999, and the other three stars were observed beginning in June 2000, with observations continuing to the present. Modeling of stellar pulsations and starspots indicate that they are not responsible for the radial velocity variations in these stars.
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Bulletin of the American Astronomical Society, 35#5
© 2003. The American Astronomical Soceity.