A super-Earth orbiting near the inner edge of the habitable zone around the M4.5 dwarf Ross 508

Harakawa, Hiroki; Takarada, Takuya; Kasagi, Yui; Hirano, Teruyuki; Kotani, Takayuki; Kuzuhara, Masayuki; Omiya, Masashi; Kawahara, Hajime; Fukui, Akihiko; Hori, Yasunori; Ishikawa, Hiroyuki Tako; Ogihara, Masahiro; Livingston, John; Brandt, Timothy D.; Currie, Thayne; Aoki, Wako; Beichman, Charles A.; Henning, Thomas; Hodapp, Klaus; Ishizuka, Masato; Izumiura, Hideyuki; Jacobson, Shane; Janson, Markus; Kambe, Eiji; Kodama, Takanori; Kokubo, Eiichiro; Konishi, Mihoko; Krishnamurthy, Vigneshwaran; Kudo, Tomoyuki; Kurokawa, Takashi; Kusakabe, Nobuhiko; Kwon, Jungmi; Matsumoto, Yuji; McElwain, Michael W.; Mitsui, Koyu; Nakagawa, Takao; Narita, Norio; Nishikawa, Jun; Nugroho, Stevanus K.; Serabyn, Eugene; Serizawa, Takuma; Takahashi, Aoi; Ueda, Akitoshi; Uyama, Taichi; Vievard, Sébastien; Wang, Ji; Wisniewski, John; Tamura, Motohide; Sato, Bun'ei
Bibliographical reference

Publications of the Astronomical Society of Japan

Advertised on:
8
2022
Number of authors
49
IAC number of authors
1
Citations
11
Refereed citations
9
Description
We report the near-infrared radial velocity (RV) discovery of a super-Earth planet on a 10.77 d orbit around the M4.5 dwarf Ross 508 (Jmag = 9.1). Using precision RVs from the Subaru Telescope IRD (InfraRed Doppler) instrument, we derive a semi-amplitude of $3.92^{+0.60}_{-0.58}\:\mbox{m}\:{\mbox{s}^{-1}}$, corresponding to a planet with a minimum mass $m \sin i = 4.00^{+0.53}_{-0.55}\, M_{\oplus }$. We find no evidence of significant signals at the detected period in spectroscopic stellar activity indicators or MEarth photometry. The planet, Ross 508 b, has a semi-major axis of $0.05366^{+0.00056}_{-0.00049}\:$au. This gives an orbit-averaged insolation of ≍1.4 times the Earth's value, placing Ross 508 b near the inner edge of its star's habitable zone. We have explored the possibility that the planet has a high eccentricity and its host is accompanied by an additional unconfirmed companion on a wide orbit. Our discovery demonstrates that the near-infrared RV search can play a crucial role in finding a low-mass planet around cool M dwarfs like Ross 508.
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