title: Extrasolar Planets around Intermediate-Mass Stars

authors: Bun'ei Sato

abstract: Intermediate-mass (1.5-5 M_sun) stars have been gathering more attention of researchers as promising sites of planet formation. It is not only because some planetary systems were found around A-type dwarfs by direct imaging but also intensive Doppler surveys of intermediate-mass giants and subgiants, which are "evolved counterparts of A-type dwarfs", have unveiled remarkable properties of planets around them: higher occurrence rate and larger typical mass of giant planets, lack of inner planets within semimajor axes of 0.6 AU, and lack of metal-rich tendency in planet-host giants. All of these properties give us deep insights into formation and evolution of planets around intermediate-mass stars.

Since 2001, we have been carrying out a Doppler planet search program targeting 300 intermediate-mass GK giants at Okayama Astrophysical Observatory. We here show the latest results of the program and discuss properties of the planets around intermediate-mass stars by comparing them with those around lower-mass stars.