Hot planets around cool stars - Two short-period mini-Neptunes transiting the late K-dwarf TOI-1260

I. Y. Georgieva, C. M. Persson, O. Barragán, G. Nowak, M. Fridlund, D. Locci, E. Palle, R. Luque, I. Carleo, D. Gandolfi, S. R. Kane, J. Korth, K. G. Stassun, J. Livingston, E. C. Matthews, K. A. Collins, S. B. Howell, L. M. Serrano, S. Albrecht, A. BierylaC. E. Brasseur, D. Ciardi, W. D. Cochran, K. D. Colon, I. J.M. Crossfield, Sz Csizmadia, H. J. Deeg, M. Esposito, E. Furlan, T. Gan, E. Goffo, E. Gonzales, S. Grziwa, E. W. Guenther, P. Guerra, T. Hirano, J. M. Jenkins, E. L.N. Jensen, P. Kabáth, E. Knudstrup, K. W.F. Lam, D. W. Latham, A. M. Levine, R. A. Matson, S. McDermott, H. L.M. Osborne, M. Paegert, S. N. Quinn, S. Redfield, G. R. Ricker, J. E. Schlieder, N. J. Scott, S. Seager, A. M.S. Smith, P. Tenenbaum, J. D. Twicken, R. Vanderspek, V. Van Eylen, J. N. Winn

Research output: Contribution to journalArticlepeer-review

3 Scopus citations

Abstract

We present the discovery and characterization of two sub-Neptunes in close orbits, as well as a tentative outer planet of a similar size, orbiting TOI-1260 - a low metallicity K6 V dwarf star. Photometry from Transiting Exoplanet Survey Satellite(TESS) yields radii of Rb = 2.33 ± 0.10 and Rc = 2.82 ± 0.15 R⊕, and periods of 3.13 and 7.49 d for TOI-1260 b and TOI-1260 c, respectively. We combined the TESS data with a series of ground-based follow-up observations to characterize the planetary system. From HARPS-N high-precision radial velocities we obtain Mb = 8.6- 1.5+ 1.4 and Mc = 11.8- 3.2+ 3.4 M⊕. The star is moderately active with a complex activity pattern, which necessitated the use of Gaussian process regression for both the light-curve detrending and the radial velocity modelling, in the latter case guided by suitable activity indicators. We successfully disentangle the stellar-induced signal from the planetary signals, underlining the importance and usefulness of the Gaussian process approach. We test the system's stability against atmospheric photoevaporation and find that the TOI-1260 planets are classic examples of the structure and composition ambiguity typical for the 2-3 R⊕ range.

Original languageEnglish (US)
Pages (from-to)4684-4701
Number of pages18
JournalMonthly Notices of the Royal Astronomical Society
Volume505
Issue number4
DOIs
StatePublished - Aug 1 2021

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Keywords

  • planetary systems
  • planets and satellites: atmospheres
  • planets and satellites: composition
  • planets and satellites: individual: TOI-1260b, c
  • stars: low-mass
  • techniques: photometric
  • techniques: radial velocities

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