* Astronomy

Title: Detection of an exoplanet around the evolved K giant HD 66141
Authors: B.-C. Lee, D. E. Mkrtichian, I. Han, M.-G. Park, K.-M. Kim

Aims. We have been carrying out a precise radial velocity (RV) survey for K giants to search for and study the origin of the lowamplitude and long-periodic RV variations. Methods. We present high-resolution RV measurements of the K2 giant HD 66141 from December 2003 to January 2011 using the fibre-fed Bohyunsan Observatory Echelle Spectrograph (BOES) at Bohyunsan Optical Astronomy Observatory (BOAO).
Results. We find that the RV measurements for HD 66141 exhibit a periodic variation of 480.5 ± 0.5 days with a semi-amplitude of 146.2 ± 2.7 m/s. The Hipparcos photometry and bisector velocity span (BVS) do not show any obvious correlations with RV variations. We find indeed 706.4 ± 35.0 day variations in equivalent width (EW) measurements of H_alpha line and 703.0 ± 39.4 day variations in a space-born measurements 1.25µ flux of HD 66141 measured during COBE/DIRBE experiment. We reveal that a mean value of long-period variations is about 705 ± 53 days and the origin is a rotation period of the star and variability that is caused by surface inhomogeneities. For the 480 day periods of RV variations an orbital motion is the most likely explanation. Assuming a stellar mass of 1.1 ± 0.1 solar masses? for HD 66141, we obtain a minimum mass for the planetary companion of 6.0 ± 0.3 Jupiter masses with an orbital semi-major axis of 1.2 ± 0.1 AU and an eccentricity of 0.07 ± 0.03.

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