A hot mini-Neptune in the radius valley orbiting solar analogue HD 110113

H. P. Osborn, D. J. Armstrong, V. Adibekyan, K. A. Collins, E. Delgado-Mena, S. B. Howell, C. Hellier, G. W. King, J. Lillo-Box, L. D. Nielsen, J. F. Otegi, N. C. Santos, C. Ziegler, D. R. Anderson, C. Briceno, C. Burke, D. Bayliss, D. Barrado, E. M. Bryant, D. J.A. BrownS. C.C. Barros, F. Bouchy, D. A. Caldwell, D. M. Conti, R. F. Diaz, D. Dragomir, M. Deleuil, O. D.S. Demangeon, C. Dorn, T. Daylan, P. Figueira, R. Helled, S. Hoyer, J. M. Jenkins, E. L.N. Jensen, D. W. Latham, N. Law, D. R. Louie, A. W. Mann, A. Osborn, D. L. Pollacco, D. R. Rodriguez, B. V. Rackham, G. Ricker, N. J. Scott, S. G. Sousa, S. Seager, K. G. Stassun, J. C. Smith, P. Strm, S. Udry, J. Villasenor, R. Vanderspek, R. West, P. J. Wheatley, J. N. Winn

Research output: Contribution to journalArticlepeer-review

Abstract

We report the discovery of HD 110113 b (TESS object of interest-755.01), a transiting mini-Neptune exoplanet on a 2.5-d orbit around the solar-analogue HD 110113 (Teff = 5730 K). Using TESS photometry and High Accuracy Radial velocity Planet Searcher (HARPS) radial velocities gathered by the NCORES program, we find that HD 110113 b has a radius of 2.05 ± 0.12 R⊕ and a mass of 4.55 ± 0.62 M⊕. The resulting density of $2.90^{+0.75}_{-0.59}$ g cm-3 is significantly lower than would be expected from a pure-rock world; therefore HD 110113 b must be a mini-Neptune with a significant volatile atmosphere. The high incident flux places it within the so-called radius valley; however, HD 110113 b was able to hold on to a substantial (0.1-1 per cent) H-He atmosphere over its ∼4 Gyr lifetime. Through a novel simultaneous Gaussian process fit to multiple activity indicators, we were also able to fit for the strong stellar rotation signal with period 20.8 ± 1.2 d from the RVs and confirm an additional non-transiting planet, HD 110113 c, which has a mass of 10.5 ± 1.2 M⊕ and a period of $6.744^{+0.008}_{-0.009}$ d.

Original languageEnglish (US)
Pages (from-to)4842-4857
Number of pages16
JournalMonthly Notices of the Royal Astronomical Society
Volume502
Issue number4
DOIs
StatePublished - Apr 1 2021

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Keywords

  • planets and satellites: detection
  • stars: individual: HD110113

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