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arXiv · 1603.02017

High-Contrast Imaging of Intermediate-Mass Giants with Long-Term Radial Velocity Trends

Tsuguru Ryu·Bun'ei Sato·Masayuki Kuzuhara·Norio Narita·Yasuhiro H. Takahashi·Taichi Uyama·Tomoyuki Kudo·Nobuhiko Kusakabe·Jun Hashimoto·Masashi Omiya·Hiroki Harakawa·Lyu Abe·Hiroyasu Ando·Wolfgang Brandner·Timothy D. Brandt·Joseph C. Carson·Thayne Currie·Sebastian Egner·Markus Feldt·Miwa Goto·Carol A. Grady·Olivier Guyon·Yutaka Hayano·Masahiko Hayashi·Saeko S. Hayashi·Krzysztof G. Hełminiak·Thomas Henning·Klaus W. Hodapp·Shigeru Ida·Miki Ishii·Yoichi Itoh·Masanori Iye·Hideyuki Izumiura·Markus Janson·Eiji Kambe·Ryo Kandori·Gillian R. Knapp·Eiichiro Kokubo·Jungmi Kwon·Taro Matsuo·Satoshi Mayama·Michael W. McElwain·Kyle Mede·Shoken Miyama·Jun-Ichi Morino·Amaya Moro-Martin·Tetsuo Nishimura·Tae-Soo Pyo·Eugene Serabyn·Takuya Suenaga·Hiroshi Suto·Ryuji Suzuki·Michihiro Takami·Naruhisa Takato·Yoichi Takeda·Hiroshi Terada·Christian Thalmann·Edwin L. Turner·Makoto Watanabe·John Wisniewski·Toru Yamada·Michitoshi Yoshida·Hideki Takami·Tomonori Usuda·Motohide Tamura
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Abstract

A radial velocity (RV) survey for intermediate-mass giants has been operated for over a decade at Okayama Astrophysical Observatory (OAO). The OAO survey has revealed that some giants show long-term linear RV accelerations (RV trends), indicating the presence of outer companions. Direct imaging observations can help clarify what objects generate these RV trends. We present the results of high-contrast imaging observations or six intermediate-mass giants with long-term RV trends using the Subaru Telescope and HiCIAO camera. We detected co-moving companions to $\gamma$ Hya B ($0.61^{+0.12}_{-0.14} M_\odot$), HD 5608 B ($0.10 \pm 0.01 M_\odot$), and HD 109272 B ($0.28 \pm 0.06 M_\odot$). For the remaining targets($\iota$ Dra, 18 Del, and HD 14067) we exclude companions more massive than 30-60 $M_\mathrm{Jup}$ at projected separations of 1arcsec-7arcsec. We examine whether these directly imaged companions or unidentified long-period companions can account for the RV trends observed around the six giants. We find that the Kozai mechanism can explain the high eccentricity of the inner planets $\iota$ Dra b, HD 5608 b, and HD 14067 b.

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Tsuguru Ryu, Bun'ei Sato, Masayuki Kuzuhara, Norio Narita, Yasuhiro H. Takahashi, Taichi Uyama, Tomoyuki Kudo, Nobuhiko Kusakabe, Jun Hashimoto, Masashi Omiya, Hiroki Harakawa, Lyu Abe, Hiroyasu Ando, Wolfgang Brandner, Timothy D. Brandt, Joseph C. Carson, Thayne Currie, Sebastian Egner, Markus Feldt, Miwa Goto, Carol A. Grady, Olivier Guyon, Yutaka Hayano, Masahiko Hayashi, Saeko S. Hayashi, Krzysztof G. Hełminiak, Thomas Henning, Klaus W. Hodapp, Shigeru Ida, Miki Ishii, Yoichi Itoh, Masanori Iye, Hideyuki Izumiura, Markus Janson, Eiji Kambe, Ryo Kandori, Gillian R. Knapp, Eiichiro Kokubo, Jungmi Kwon, Taro Matsuo, Satoshi Mayama, Michael W. McElwain, Kyle Mede, Shoken Miyama, Jun-Ichi Morino, Amaya Moro-Martin, Tetsuo Nishimura, Tae-Soo Pyo, Eugene Serabyn, Takuya Suenaga, Hiroshi Suto, Ryuji Suzuki, Michihiro Takami, Naruhisa Takato, Yoichi Takeda, Hiroshi Terada, Christian Thalmann, Edwin L. Turner, Makoto Watanabe, John Wisniewski, Toru Yamada, Michitoshi Yoshida, Hideki Takami, Tomonori Usuda, Motohide Tamura. 2016-03-07. High-Contrast Imaging of Intermediate-Mass Giants with Long-Term Radial Velocity Trends. https://doi.org/10.3847/0004-637x/825/2/127

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