G and K giants are a class of radial velocity (RV) variables. One reason for this variability are planetary companions which are indicated in time series of stellar spectra. Since 2004 these spectra in the visual range were obtained with the high resolution coud\'e \'echelle spectrograph mounted on the 2m telescope of the Th\"uringer Landessternwarte Tautenburg (TLS) for a northern sample of 62 very bright K giants. In the South around 300 G and K giants were observed with HARPS mounted on the 3.6m telescope on La Silla. The TLS sample contains at least 11 stars (18 %) which show low-amplitude, long-period RV variations most likely due to planets. This percentage of planet frequency is confirmed by preliminary results of the HARPS study. Moreover the TLS survey seems to indicate that giant planets do not favour metal-rich stars, are more massive, and have longer periods than those found around solar-type host stars.
@article{arxiv.1102.0499,
title = {Exoplanets around G-K Giants},
author = {M. P. Döllinger and A. P. Hatzes and L. Pasquini and E. W. Guenther and M. Hartmann and J. Setiawan and L. Girardi and J. R. de Medeiros and L. da Silva},
journal= {arXiv preprint arXiv:1102.0499},
year = {2011}
}
Comments
Part of PlanetsbeyondMS/2010 proceedings http://arxiv.org/html/1011.6606