Search for extrasolar planets in binary systems

Abstract

We are searching for extrasolar planets in binary systems to understand the planet formation in binary or multiple star systems by precise Doppler shift measurements, using HIgh Dispersion Echelle Spectrograph(HIDES) equipped on the Okayama Astrophysical Observatory's(OAO) 188cm telescope.Since 2003, we have monitored radial velocity variations about 10 pairs of visual binary systems every 1 or 2 month. We have reported about these stars in 2004 and 2005 autumn meeting.On last August, we have started a Doppler survey for SB1s(single-lined spectroscopic binary) with semi-major axis smaller than 10AU. The orbital elements of such binaries are well determined. We have selected target stars which orbital elements(period, eccentricity, amplitude) are already given. We can observationally investigate the distribution of binary's semi-major axis, which planets can stably exist, as a function of eccentricity.We will present the current status of the this survey and future works.