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

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. HowellD. 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

Research output: Contribution to journalArticlepeer-review

Abstract

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.

Original languageEnglish (US)
Article numberA60
JournalAstronomy and Astrophysics
Volume653
DOIs
StatePublished - Sep 1 2021

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Keywords

  • Planets and satellites: gaseous planets
  • Planets and satellites: general
  • Stars: individual: TOI-674
  • Techniques: photometric
  • Techniques: radial velocities

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