Exoplanets & Exomoons

HD 21520 b: A Warm Sub-Neptune Transiting A Bright G Dwarf

By Keith Cowing
Status Report
June 17, 2024
Filed under , , , , , , , , , , , , ,
HD 21520 b: A Warm Sub-Neptune Transiting A Bright G Dwarf
Phase folded TESS transit data with modeled allesfitter fit (grey), and residuals plot on the bottom. Also plotted are the phase folded points binned to 30 minutes (black). — astro-ph.EP

We report the discovery and validation of HD 21520 b, a transiting planet found with TESS and orbiting a bright G dwarf (V=9.2, Teff=5871±62 K, R=1.04±0.02R).

HD 21520 b was originally alerted as a system (TOI-4320) consisting of two planet candidates with periods of 703.6 and 46.4 days. However, our analysis supports instead a single-planet system with an orbital period of 25.1292±0.0001 days and radius of 2.70±0.09R. Three full transits in sectors 4, 30 and 31 match this period and have transit depths and durations in agreement with each other, as does a partial transit in sector 3. We also observe transits using CHEOPS and LCOGT.

SOAR and Gemini high-resolution imaging do not indicate the presence of any nearby companions, and MINERVA-Australis and CORALIE radial velocities rule out an on-target spectroscopic binary. Additionally, we use ESPRESSO radial velocities to obtain a tentative mass measurement of 7.9+3.2−3.0M, with a 3-σ upper limit of 17.7 M. Due to the bright nature of its host and likely significant gas envelope of the planet, HD 21520 b is a promising candidate for further mass measurements and for atmospheric characterization.

Molly Nies, Ismael Mireles, François Bouchy, Diana Dragomir, Belinda A. Nicholson, Nora L. Eisner, Sergio G. Sousa, Karen A. Collins, Steve B. Howell, Carl Ziegler, Coel Hellier, Brett Addison, Sarah Ballard, Brendan P. Bowler, César Briceño, Catherine A. Clark, Dennis M. Conti, Xavier Dumusque, Billy Edwards, Crystal L. Gnilka, Melissa Hobson, Jonathan Horner, Stephen R. Kane, John Kielkopf, Baptiste Lavie, Nicholas Law, Monika Lendl, Colin Littlefield, Huigen Liu, Andrew W. Mann, Matthew W. Mengel, Dominic Oddo, Jack Okumura, Enric Palle, Peter Plavchan, Angelica Psaridi, Nuno C. Santos, Richard P. Schwarz, Avi Shporer, Robert A. Wittenmyer, Duncan J. Wright, Hui Zhang, David Watanabe, Jennifer V. Medina, Joel Villaseñor, Eric B. Ting, Jessie L. Christiansen, Joshua N. Winn, Keivan G. Stassun, S. Seager, David W. Latham, George R. Ricker

Comments: Submitted to MNRAS
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2406.09595 [astro-ph.EP] (or arXiv:2406.09595v1 [astro-ph.EP] for this version)
Submission history
From: Ismael Mireles
[v1] Thu, 13 Jun 2024 21:27:51 UTC (13,937 KB)

Explorers Club Fellow, ex-NASA Space Station Payload manager/space biologist, Away Teams, Journalist, Lapsed climber, Synaesthete, Na’Vi-Jedi-Freman-Buddhist-mix, ASL, Devon Island and Everest Base Camp veteran, (he/him) 🖖🏻