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

doi:10.3847/0004-637X/825/2/127

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

Astrophys J. 2016 Jul 10;825(2):127. doi: 10.3847/0004-637X/825/2/127. Epub 2016 Jul 12.

Authors

Tsuguru Ryu^{1

2}, Bun'ei Sato³, Masayuki Kuzuhara³, Norio Narita^{1

2

4}, Yasuhiro H Takahashi⁵, Taichi Uyama⁵, Tomoyuki Kudo⁶, Nobuhiko Kusakabe⁴, Jun Hashimoto⁴, Masashi Omiya², Hiroki Harakawa², Lyu Abe⁷, Hiroyasu Ando², Wolfgang Brandner⁸, Timothy D Brandt⁹, Joseph C Carson^{10

8}, Thayne Currie⁶, Sebastian Egner⁶, Markus Feldt⁸, Miwa Goto¹¹, Carol A Grady^{12

13

14}, Olivier Guyon⁶, Yutaka Hayano⁶, Masahiko Hayashi², Saeko S Hayashi⁶, Krzysztof G Hełminiak⁶, Thomas Henning⁸, Klaus W Hodapp¹⁵, Shigeru Ida³, Miki Ishii², Yoichi Itoh¹⁶, Masanori Iye², Hideyuki Izumiura^{1

17}, Markus Janson¹⁸, Eiji Kambe¹⁷, Ryo Kandori², Gillian R Knapp¹⁸, Eiichiro Kokubo^{1

2}, Jungmi Kwon⁵, Taro Matsuo¹⁹, Satoshi Mayama¹, Michael W McElwain²⁰, Kyle Mede⁵, Shoken Miyama²¹, Jun-Ichi Morino², Amaya Moro-Martin^{22

23}, Tetsuo Nishimura⁶, Tae-Soo Pyo⁶, Eugene Serabyn²⁴, Takuya Suenaga^{1

2}, Hiroshi Suto^{2

4}, Ryuji Suzuki², Michihiro Takami²⁵, Naruhisa Takato⁶, Yoichi Takeda^{1

2}, Hiroshi Terada², Christian Thalmann²⁶, Edwin L Turner^{19

27}, Makoto Watanabe²⁸, John Wisniewski²⁹, Toru Yamada³⁰, Michitoshi Yoshida³¹, Hideki Takami², Tomonori Usuda², Motohide Tamura^{2

4

5}

Affiliations

¹ SOKENDAI, The Graduate University for Advanced Studies, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan.
² National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan.
³ Department of Earth and Planetary Sciences, Tokyo Institute of Technology, Ookayama, Meguro-ku, Tokyo 152-8551, Japan.
⁴ Astrobiology Center, 2-21-1 Osawa, Mitaka, Tokyo, 181-8588, Japan.
⁵ Department of Astronomy, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.
⁶ Subaru Telescope, National Astronomical Observatory of Japan, 650 North Aohoku Place, Hilo, HI96720, USA.
⁷ Laboratoire Lagrange (UMR 7293), Universite de Nice-Sophia Antipolis, CNRS, Observatoire de la Coted'azur,28 avenue Valrose, 06108 Nice Cedex 2, France.
⁸ Max Planck Institute for Astronomy, Königstuhl 17, 69117 Heidelberg, Germany.
⁹ Astrophysics Department, Institute for Advanced Study, Princeton, NJ, USA.
¹⁰ Department of Physics and Astronomy, College of Charleston, 58 Coming St., Charleston, SC 29424, USA.
¹¹ Universitäts-Sternwarte Munchen, Ludwig-Maximilians-Universität, Scheinerstr. 1, 81679 Munchen,Germany.
¹² Exoplanets and Stellar Astrophysics Laboratory, Code 667, Goddard Space Flight Center, Greenbelt, MD 20771, USA.
¹³ Eureka Scientific, 2452 Delmer, Suite 100, Oakland CA96002, USA.
¹⁴ Goddard Center for Astrobiology.
¹⁵ Institute for Astronomy, University of Hawaii, 640 N. A'ohoku Place, Hilo, HI 96720, USA.
¹⁶ Nishi-Harima Astronomical Observatory, Center for Astronomy,University of Hyogo, 407-2, Nishigaichi, Sayo, Hyogo, 679-5313, Japan.
¹⁷ Okayama Astrophysical Observatory, National Astronomical Observatory of Japan, Kamogata, Okayama 719-0232, Japan.
¹⁸ Department of Astrophysical Science, Princeton University, Peyton Hall, Ivy Lane, Princeton, NJ08544, USA.
¹⁹ Department of Astronomy, Kyoto University, Kitashirakawa-Oiwake-cho, Sakyo-ku, Kyoto, Kyoto 606-8502, Japan.
²⁰ Exoplanets and Stellar Astrophysics Laboratory, Code 667, Goddard Space Flight Center, Greenbelt, MD20771, USA.
²¹ Hiroshima University, 1-3-2, Kagamiyama, Higashihiroshima, Hiroshima 739-8511, Japan.
²² Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA.
²³ Center for Astrophysical Sciences, Johns Hopkins University, Baltimore MD 21218, USA.
²⁴ Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, 171-113, USA.
²⁵ Institute of Astronomy and Astrophysics, Academia Sinica, P.O. Box 23-141, Taipei 10617, Taiwan.
²⁶ ETH Zurich, Institute for Astronomy, Wolfgang-Pauli-Strasse 27, 8093 Zurich, Switzerland.
²⁷ Kavli Institute for Physics and Mathematics of the Universe, The University of Tokyo, 5-1-5, Kashiwanoha, Kashiwa, Chiba 277-8568, Japan.
²⁸ Department of Cosmosciences, Hokkaido University, Kita-ku, Sapporo, Hokkaido 060-0810, Japan.
²⁹ H. L. Dodge Department of Physics & Astronomy, University of Oklahoma, 440 W Brooks St Norman, OK 73019, USA.
³⁰ Astronomical Institute, Tohoku University, Aoba-ku, Sendai, Miyagi 980-8578, Japan.
³¹ Hiroshima Astrophysical Science Center, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526, Japan.

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 of six intermediate-mass giants with long-term RV trends using the Subaru Telescope and HiCIAO camera. We detected co-moving companions to γ Hya $B ({0.61}_{- 0.14}^{+ 0.12} M_{⊙})$ , HD 5608 B (0.10 ± 0.01M _⊙), and HD 109272 B (0.28 ± 0.06M _⊙). For the remaining targets(ι Dra, 18 Del, and HD 14067) we exclude companions more massive than 30-60 M _Jup at projected separations of 1''-7''. 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 ι Dra b, HD 5608 b, and HD 14067 b.

Keywords: binaries: general; –methods: observational; –planetary systems – stars: individual(γ Hya, ι Dra, HD 5608, HD 14067, HD 109272); –techniques: high angular resolution; –techniques: radial velocities.

Grants and funding

SCMD-Astrophysics/Science Astrophysics NASA/United States