Direct imaging search for extrasolar planets in the pleiades

Kodai Yamamoto, Taro Matsuo, Hiroshi Shibai, Yoichi Itoh, Mihoko Konishi, Jun Sudo, Ryoko Tanii, Misato Fukagawa, Takahiro Sumi, Tomoyuki Kudo, Jun Hashimoto, Nobuhiko Kusakabe, Lyu Abe, Wolfgang Brandner, Timothy D. Brandt, Joseph Carson, Thayne Currie, Sebastian E. Egner, Markus Feldt, Miwa GotoCarol Grady, Olivier Guyon, Yutaka Hayano, Masahiko Hayashi, Saeko Hayashi, Thomas Henning, Klaus Hodapp, Miki Ishii, Masanori Iye, Markus Janson, Ryo Kandori, Gillian R. Knapp, Masayuki Kuzuhara, Jungmi Kwon, Mike Mcelwain, Shoken Miyama, Jun Ichi Morino, Amaya Moro-Martin, June Nishikawa, Tetsuo Nishimura, Tae Soo Pyo, Eugene Serabyn, Hiroshi Suto, Ryuji Suzuki, Michihiro Takami, Naruhisa Takato, Hiroshi Terada, Christian Thalmann, Daigo Tomono, Edwin L. Turner, John Wisniewski, Makoto Watanabe, Toru Yamada, Hideki Takami, Tomonori Usuda, Motohide Tamura

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26 Scopus citations


We carried out an imaging survey for extrasolar planets around stars in the Pleiades (125 Myr, 135 pc) in the H and KS bands using HiCIAO combined with adaptive optics, AO188, on the Subaru telescope. We found 13 companion candidates fainter than 14.5 mag in the H band around 9 stars. Five of these 13 were confirmed to be background stars by measurement of their proper motion. One was not found in the second epoch observation, and thus was not a background or companion object. One had multi-epoch images, but the precision of its proper motion was not sufficient to conclude whether it was a background object. Four other candidates are waiting for second-epoch observations to determine their proper motion. Finally, the remaining two were confirmed to be 60MJ brown dwarf companions orbiting around HD 23514 (G0) and HII 1348 (K5), respectively, as had been reported in previous studies. In our observations, the average detection limit for a point source was 20.3 mag in the H band beyond 1:005 from the central star. On the basis of this detection limit, we calculated the detection efficiency to be 90% for a planet with 6 to 12 Jovian masses and a semi-major axis of 50-1000 AU. For this reason we extrapolated the distribution of the planet mass and the semi-major axis derived from radial velocity observations, and adopted the planet evolution model Baraffe et al. (2003, A&A, 402, 701). Since there was no detection of a planet, we estimated the frequency of such planets to be less than 17.9% (2) around one star of the Pleiades cluster.

Original languageEnglish (US)
Article number90
JournalPublications of the Astronomical Society of Japan
Issue number4
StatePublished - Aug 25 2013

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


  • Brown dwarfs
  • Infrared: stars
  • Methods: statistical
  • Stars: low-mass
  • Stars: planetary systems
  • Techniques: high angular resolution


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