Direct imaging detection of methane in the atmosphere of GJ 504 b

Markus Janson, Timothy D. Brandt, Masayuki Kuzuhara, David S. Spiegel, Christian Thalmann, Thayne Currie, Mickaël Bonnefoy, Neil Zimmerman, Satoko Sorahana, Takayuki Kotani, Joshua Schlieder, Jun Hashimoto, Tomoyuki Kudo, Nobuhiko Kusakabe, Lyu Abe, Wolfgang Brandner, Joseph C. Carson, Sebastian Egner, Markus Feldt, Miwa GotoCarol A. Grady, Olivier Guyon, Yutaka Hayano, Masahiko Hayashi, Saeko Hayashi, Thomas Henning, Klaus W. Hodapp, Miki Ishii, Masanori Iye, Ryo Kandori, Gillian R. Knapp, Jungmi Kwon, Taro Matsuo, Michael W. McElwain, Kyle Mede, Shoken Miyama, Jun Ichi Morino, Amaya Moro-Martín, Takao Nakagawa, Tetsuro Nishimura, Tae Soo Pyo, Eugene Serabyn, Takuya Suenaga, Hiroshi Suto, Ryuji Suzuki, Yasuhiro Takahashi, Michihiro Takami, Naruhisa Takato, Hiroshi Terada, Daego Tomono, Edwin L. Turner, Makoto Watanabe, John Wisniewski, Toru Yamada, Hideki Takami, Tomonori Usuda, Motohide Tamura

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61 Scopus citations


Most exoplanets detected by direct imaging thus far have been characterized by relatively hot (≳1000 K) and cloudy atmospheres. A surprising feature in some of their atmospheres has been a distinct lack of methane, possibly implying non-equilibrium chemistry. Recently, we reported the discovery of a planetary companion to the Sun-like star GJ 504 using Subaru/HiCIAO within the Strategic Exploration of Exoplanets and Disks with Subaru survey. The planet is substantially colder (<600 K) than previously imaged planets, and has indications of fewer clouds, which implies that it represents a new class of planetary atmospheres with expected similarities to late T-type brown dwarfs in the same temperature range. If so, one might also expect the presence of significant methane absorption, which is characteristic of such objects. Here, we report the detection of deep methane absorption in the atmosphere of GJ 504 b, using the Spectral Differential Imaging mode of HiCIAO to distinguish the absorption features around 1.6 μm. We also report updated JHK photometry based on new K s-band data and a re-analysis of the existing data. The results support the notion that GJ 504 b has atmospheric properties distinct from other imaged exoplanets, and will become a useful reference object for future planets in the same temperature range.

Original languageEnglish (US)
Article numberL4
JournalAstrophysical Journal Letters
Issue number1
StatePublished - Nov 20 2013

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


  • planetary systems
  • stars: solar-type
  • techniques: photometric


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