HD 21520 b: a warm sub-Neptune transiting a bright G dwarf
Year: 2024
Type: article
Abstract: ABSTRACT We report the discovery and validation of HD 21520 b, a transiting planet found with Transiting Exoplanet Survey Satellite and orbiting a bright G dwarf (V = 9.2, $T_{\rm eff} = 5871 \pm 62$ K, $R_{\star } = 1.04\pm 0.02\, {\rm R}_{\odot }$). HD 21520 b was originally alerted as a system (TOI-4320) consisting of two planet candidates with periods of 703.6 and 46.4 d. However, our analysis supports instead a single-planet system with an orbital period of $25.1292\pm 0.0001$ d and radius of $2.70 \pm 0.09\, {\rm R}_{{\oplus }}$. 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 $7.9^{+3.2}_{-3.0}\, {\rm M}_{{\oplus }}$, with a 3$\sigma$ upper limit of 17.7 ${\rm M}_{{\oplus }}$. Due to the bright nature of its host and likely significant gas envelope of the planet, HD 21520b is a promising candidate for further mass measurements and for atmospheric characterization.
Authors: 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
Institutions: East Stroudsburg University, University of New Mexico, University of Geneva, University of Southern Queensland, University of Oxford, Flatiron Institute, Universidade do Porto, Institute of Astrophysics and Space Sciences, Centro de Astrofísica da Universidade do Porto, Center for Astrophysics Harvard & Smithsonian, Ames Research Center, Stephen F. Austin State University, Keele University, Swinburne University of Technology, University of Florida, The University of Texas at Austin, Cerro Tololo Inter-American Observatory, California Institute of Technology, Jet Propulsion Laboratory, NASA Exoplanet Science Institute, American Association of Variable Star Observers, Space Research Organisation Netherlands, University of California, Riverside, University of Louisville, University of North Carolina at Chapel Hill, Bay Area Environmental Research Institute, Nanjing University, Universidad de La Laguna, Instituto de Astrofísica de Canarias, George Mason University, Massachusetts Institute of Technology, Chinese Academy of Sciences, Shanghai Astronomical Observatory, Space Telescope Science Institute, Princeton University, Vanderbilt University
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $3,012
Funders: National Science Foundation, National Aeronautics and Space Administration, George Mason University, California Institute of Technology, University of Florida, University of Louisville, University of Texas at Austin, Agencia Nacional de Investigación e Innovación, National Research Council Sri Lanka, Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung, University of Southern Queensland, Ministério da Ciência, Tecnologia e Inovação, Korea Astronomy and Space Science Institute, Jet Propulsion Laboratory, Australian Research Council
Awards: G1121736267, TITANIA: TIme variabiliTy As a New window on exoplanet clImAtes, Light from darkness: understanding extrasolar planets from their shadows, Catch me if you can: The race to rescue the smallest planets, G3648211085, G6799506111, NCCR PlanetS: Origin, evolution and characterisation of planets, G8505061131, MINERVA-Australis: A dedicated southern hemisphere exoplanet observatory
OpenAlex ID: W4402288657