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Journal Articles The Astrophysical journal letters Year : 2022

HD 56414 b: A Warm Neptune Transiting an A-type Star

Steven Giacalone
  • Function : Author
Courtney D. Dressing
  • Function : Author
Matthew J. Hooton
  • Function : Author
Keivan G. Stassun
  • Function : Author
Samuel N. Quinn
  • Function : Author
George Zhou
  • Function : Author
Carl Ziegler
  • Function : Author
Roland Vanderspek
  • Function : Author
David W. Latham
  • Function : Author
S. Seager
  • Function : Author
Joshua N. Winn
  • Function : Author
Jon M. Jenkins
  • Function : Author
César Briceño
  • Function : Author
Chelsea X. Huang
  • Function : Author
David R. Rodriguez
  • Function : Author
Avi Shporer
  • Function : Author
Andrew W. Mann
  • Function : Author
David Watanabe
  • Function : Author
Bill Wohler
  • Function : Author

Abstract

We report the discovery in TESS data and validation of HD 56414 b (a.k.a. TOI-1228 b), a Neptune-size (R p = 3.71 ± 0.20 R ) planet with a 29 day orbital period transiting a young (age = 420 ± 140 Myr) A-type star in the TESS southern continuous-viewing zone. HD 56414 is one of the hottest stars (T eff = 8500 ± 150 K) to host a known sub-Jovian planet. HD 56414 b lies on the boundary of the hot Neptune desert in the planet radius-bolometric insolation flux space, suggesting that the planet may be experiencing mass loss. To explore this, we apply a photoevaporation model that incorporates the high near-ultraviolet continuum emission of A-type stars. We find that the planet can retain most of its atmosphere over the typical 1 Gyr main-sequence lifetime of an A-type star if its mass is ≥8 M . Our model also predicts that close-in Neptune-size planets with masses <14 M are susceptible to total atmospheric stripping over 1 Gyr, hinting that the hot Neptune desert, which has been previously observed around FGKM-type stars, likely extends to A-type stars.
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insu-03846754 , version 1 (10-11-2022)

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Steven Giacalone, Courtney D. Dressing, A. García Muñoz, Matthew J. Hooton, Keivan G. Stassun, et al.. HD 56414 b: A Warm Neptune Transiting an A-type Star. The Astrophysical journal letters, 2022, 935, ⟨10.3847/2041-8213/ac80f4⟩. ⟨insu-03846754⟩
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