The TESS-Keck Survey. XII. A Dense 1.8 R _⊕ Ultra-short-period Planet Possibly Clinging to a High-mean-molecular-weight Atmosphere after the First Gigayear

April 2024 • 2024AJ....167..153R

Authors • Rubenzahl, Ryan A. • Dai, Fei • Howard, Andrew W. • Lissauer, Jack J. • Van Zandt, Judah • Beard, Corey • Giacalone, Steven • Murphy, Joseph M. Akana • Chontos, Ashley • Lubin, Jack • Brinkman, Casey L. • Tyler, Dakotah • MacDougall, Mason G. • Rice, Malena • Dalba, Paul A. • Mayo, Andrew W. • Weiss, Lauren M. • Polanski, Alex S. • Blunt, Sarah • Yee, Samuel W. • Hill, Michelle L. • Angelo, Isabel • Turtelboom, Emma V. • Holcomb, Rae • Behmard, Aida • Pidhorodetska, Daria • Batalha, Natalie M. • Crossfield, Ian J. M. • Dressing, Courtney • Fulton, Benjamin • Huber, Daniel • Isaacson, Howard • Kane, Stephen R. • Petigura, Erik A. • Robertson, Paul • Scarsdale, Nicholas • Mocnik, Teo • Fetherolf, Tara • Malavolta, Luca • Mortier, Annelies • Fiorenzano, Aldo • Pedani, Marco

Abstract • The extreme environments of ultra-short-period planets (USPs) make excellent laboratories to study how exoplanets obtain, lose, retain, and/or regain gaseous atmospheres. We present the confirmation and characterization of the USP TOI-1347 b, a 1.8 ± 0.1 R _⊕ planet on a 0.85 day orbit that was detected with photometry from the TESS mission. We measured radial velocities of the TOI-1347 system using Keck/HIRES and HARPS-N and found the USP to be unusually massive at 11.1 ± 1.2 M _⊕. The measured mass and radius of TOI-1347 b imply an Earth-like bulk composition. A thin H/He envelope (>0.01% by mass) can be ruled out at high confidence. The system is between 1 and 1.8 Gyr old; therefore, intensive photoevaporation should have concluded. We detected a tentative phase-curve variation (3σ) and a secondary eclipse (2σ) in TESS photometry, which, if confirmed, could indicate the presence of a high-mean-molecular-weight atmosphere. We recommend additional optical and infrared observations to confirm the presence of an atmosphere and investigate its composition.

Links

• PREPRINT http://arxiv.org/abs/2402.07451
• ELECTR https://doi.org/10.3847%2F1538-3881%2Fad28bb
• SIMBAD http://simbad.u-strasbg.fr/simbo.pl?bibcode=2024AJ....167..153R
• PDF https://iopscience.iop.org/article/10.3847/1538-3881/ad28bb/pdf
• DATA http://cdsarc.cds.unistra.fr/viz-bin/cat/J/AJ/167/153
• DATA https://archive.gemini.edu/searchform/publication=2024AJ....167..153R
• DATA https://doi.org/10.17909/fwdt-2x66
• DATA https://doi.org/10.17909/t9-nmc8-f686
• DATA https://doi.org/10.26133/NEA1