A super-Earth orbiting near the inner edge of the habitable zone around the M4.5 dwarf Ross 508. (30th June 2022)

• Record Type: Journal Article
• Authors: 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;
• Is Part Of: Publications of the Astronomical Society of Japan. Volume 74:Number 4(2022)
• Page Start: 904
• Page End: 922
• Publication Date: 2022-06-30
• Subjects: infrared: planetary systems -- planets and satellites: terrestrial planets -- techniques: radial velocities; Astronomy -- Periodicals; 520.5
• DOI: 10.1093/pasj/psac044
• Languages: English
• ISSNs: 0004-6264

Abstract

Abstract: 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 ( J mag = 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.