TOI-1696: A Nearby M4 Dwarf with a 3 R Planet in the Neptunian Desert

Mayuko Mori, John H. Livingston, Jerome De Leon, Norio Narita, Teruyuki Hirano, Akihiko Fukui, Karen A. Collins, Naho Fujita, Yasunori Hori, Hiroyuki Tako Ishikawa, Kiyoe Kawauchi, Keivan G. Stassun, Noriharu Watanabe, Steven Giacalone, Rebecca Gore, Ashley Schroeder, Courtney D. Dressing, Allyson Bieryla, Eric L.N. Jensen, Bob MasseyAvi Shporer, Masayuki Kuzuhara, David Charbonneau, David R. Ciardi, John P. Doty, Emma Esparza-Borges, Hiroki Harakawa, Klaus Hodapp, Masahiro Ikoma, Kai Ikuta, Keisuke Isogai, Jon M. Jenkins, Taiki Kagetani, Tadahiro Kimura, Takanori Kodama, Takayuki Kotani, Vigneshwaran Krishnamurthy, Tomoyuki Kudo, Seiya Kurita, Takashi Kurokawa, Nobuhiko Kusakabe, David W. Latham, Brian McLean, Felipe Murgas, Jun Nishikawa, Taku Nishiumi, Masashi Omiya, Hugh P. Osborn, Enric Palle, Hannu Parviainen, George R. Ricker, Sara Seager, Takuma Serizawa, Huan Yu Teng, Yuka Terada, Joseph D. Twicken, Akitoshi Ueda, Roland Vanderspek, Sébastien Vievard, Joshua N. Winn, Yujie Zou, Motohide Tamura

Research output: Contribution to journalArticlepeer-review

Abstract

We present the discovery and validation of a temperate sub-Neptune around the nearby mid-M dwarf TIC 470381900 (TOI-1696), with a radius of 3.09 ± 0.11 R and an orbital period of 2.5 days, using a combination of Transiting Exoplanets Survey Satellite (TESS) and follow-up observations using ground-based telescopes. Joint analysis of multiband photometry from TESS, Multicolor Simultaneous Camera for studying Atmospheres of Transiting exoplanets (MuSCAT), MuSCAT3, Sinistro, and KeplerCam confirmed the transit signal to be achromatic as well as refined the orbital ephemeris. High-resolution imaging with Gemini/'Alopeke and high-resolution spectroscopy with the Subaru InfraRed Doppler (IRD) confirmed that there are no stellar companions or background sources to the star. The spectroscopic observations with IRD and Infrared Telescope Facility SpeX were used to determine the stellar parameters, and it was found that the host star is an M4 dwarf with an effective temperature of T eff = 3185 ± 76 K and a metallicity of [Fe/H] = 0.336 ± 0.060 dex. The radial velocities measured from IRD set a 2σ upper limit on the planetary mass to be 48.8 M. The large radius ratio (R p/R ∼0.1) and the relatively bright near-infrared magnitude (J = 12.2 mag) make this planet an attractive target for further follow-up observations. TOI-1696 b is one of the planets belonging to the Neptunian desert with the highest transmission spectroscopy metric discovered to date, making it an interesting candidate for atmospheric characterizations with JWST.

Original languageEnglish (US)
Article number298
JournalAstronomical Journal
Volume163
Issue number6
DOIs
StatePublished - Jun 1 2022

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

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