TOI-674b : An oasis in the desert of exo-Neptunes transiting a nearby M dwarf

Summary, in English

Context. The NASA mission TESS is currently doing an all-sky survey from space to detect transiting planets around bright stars. As part of the validation process, the most promising planet candidates need to be confirmed and characterized using follow-up observations. Aims. In this article, our aim is to confirm the planetary nature of the transiting planet candidate TOI-674b using spectroscopic and photometric observations. Methods. We use TESS, Spitzer, ground-based light curves, and HARPS spectrograph radial velocity measurements to establish the physical properties of the transiting exoplanet candidate TOI-674b. We perform a joint fit of the light curves and radial velocity time series to measure the mass, radius, and orbital parameters of the candidate. Results. We confirm and characterize TOI-674b, a low-density super-Neptune transiting a nearby M dwarf. The host star (TIC 158588995, V = 14.2 mag, J = 10.3 mag) is characterized by its M2V spectral type with M = 0.420 ± 0.010 M , R = 0.420 ± 0.013 R , and Teff = 3514 ± 57 K; it is located at a distance d = 46.16 ± 0.03 pc. Combining the available transit light curves plus radial velocity measurements and jointly fitting a circular orbit model, we find an orbital period of 1.977143 ± 3 × 10-6 days, a planetary radius of 5.25 ± 0.17 R , and a mass of 23.6 ± 3.3 M implying a mean density of ρp =0.91 ± 0.15 g cm-3. A non-circular orbit model fit delivers similar planetary mass and radius values within the uncertainties. Given the measured planetary radius and mass, TOI-674b is one of the largest and most massive super-Neptune class planets discovered around an M-type star to date. It is found in the Neptunian desert, and is a promising candidate for atmospheric characterization using the James Webb Space Telescope.

• Author: F. Murgas; N. Astudillo-Defru; X. Bonfils; I. Crossfield; J. M. Almenara; J. Livingston; K. G. Stassun; J. Korth; J. Orell-Miquel; G. Morello; J. D. Eastman; J. J. Lissauer; S. R. Kane; F. Y. Morales; M. W. Werner; V. Gorjian; B. Benneke; D. Dragomir; E. C. Matthews; S. B. Howell; D. Ciardi; E. Gonzales; R. Matson; C. Beichman; J. Schlieder; K. A. Collins; K. I. Collins; E. L.N. Jensen; P. Evans; F. J. Pozuelos; M. Gillon; E. Jehin; K. Barkaoui; E. Artigau; F. Bouchy; D. Charbonneau; X. Delfosse; R. F. Díaz; R. Doyon; P. Figueira; T. Forveille; C. Lovis; C. Melo; G. Gaisné; F. Pepe; N. C. Santos; D. Ségransan; S. Udry; R. F. Goeke; A. M. Levine; E. V. Quintana; N. M. Guerrero; I. Mireles; D. A. Caldwell; P. Tenenbaum; C. E. Brasseur; G. Ricker; R. Vanderspek; D. W. Latham; S. Seager; J. Winn; J. M. Jenkins
• Publishing year: 2021-09-01
• Language: English
• Publication/Series: Astronomy and Astrophysics
• Volume: 653
• Links: http://dx.doi.org/10.1051/0004-6361/202140718
• Document type: Journal article
• Publisher: EDP Sciences
• Keywords: Planets and satellites: gaseous planets; Planets and satellites: general; Stars: individual: TOI-674; Techniques: photometric; Techniques: radial velocities
• Status: Published
• ISBN/ISSN/Other: ISSN: 0004-6361