HD 21520 b: a warm sub-Neptune transiting a bright G dwarf

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.

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Publication Details

Journal
Monthly Notices of the Royal Astronomical Society
Published
2024-09-05
DOI
https://doi.org/10.1093/mnras/stae2079
Citations
3
Primary Topic
Stellar, planetary, and galactic studies
Type
article
Field-Weighted Citation Impact
0.99

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article

HD 21520 b: a warm sub-Neptune transiting a bright G dwarf

Ismael Mireles, F. Bouchy, Andrew W. Mann, Crystal L. Gnilka et al.
3 citations
Monthly Notices of the Royal Astronomical Society
Stellar, planetary, and galactic studies
0.99
article

HD 21520 b: a warm sub-Neptune transiting a bright G dwarf

Ismael Mireles, F. Bouchy, Andrew W. Mann, Crystal L. Gnilka, Stephen R. Kane, Hui Zhang, Robert A. Wittenmyer, M. Lendl, Angelica Psaridi, Ε. Πάλλη, Peter Plavchan, David W. Latham, B. Lavie, Diana Dragomir, Karen A. Collins, Steve B. Howell, Brendan P. Bowler, Eric B. Ting, Sara Seager, Nora L. Eisner, Brett Addison, Richard P. Schwarz, Nicholas M. Law, Dominic Oddo, Jack Okumura, Colin Littlefield, Belinda Nicholson, G. Ricker, Hui-Gen Liu, Catherine A. Clark, Sarah Ballard, David Watanabe, Jonathan Horner, Avi Shporer, Dennis M. Conti, C. Hellier, N. C. Santos, Jennifer Medina, Jessie L. Christiansen, Matthew W. Mengel, John F. Kielkopf, D. J. Wright, Mélissa J. Hobson, X. Dumusque, Billy Edwards, Keivan G. Stassun, Molly Nies, S. G. Sousa, César Briceño, J. Villaseñor, Carl Ziegler, Joshua N. Winn
article en
3 citations

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.

Monthly Notices of the Royal Astronomical SocietyVol. 534(4)
University of California, Riverside (US), University of North Carolina at Chapel Hill (US), University of Geneva (CH), California Institute of Technology (US), Ames Research Center (US), Space Telescope Science Institute (US), Jet Propulsion Laboratory (US), University of Louisville (US), Universidad de La Laguna (ES), George Mason University (US), University of New Mexico (US), Universidade do Porto (PT), University of Southern Queensland (AU), American Association of Variable Star Observers (US), Vanderbilt University (US), Princeton University (US), Stephen F. Austin State University (US), Shanghai Astronomical Observatory (CN), NASA Exoplanet Science Institute (US), University of Florida (US), University of Oxford (GB), Institute of Astrophysics and Space Sciences (PT), Kavli Institute for Particle Astrophysics and Cosmology (US), Bay Area Environmental Research Institute (US), Université Bourgogne Franche-Comté (FR), Center for Astrophysics Harvard & Smithsonian (US), Instituto de Astrofísica de Canarias (ES), Observatoire Cantonal de Neuchâtel (CH), Cerro Tololo Inter-American Observatory (CL), Astronomy and Space (AU), Flatiron Health (United States) (US), Flatiron Institute (US), American Institute of Aeronautics and Astronautics (US), Space Research Organisation Netherlands (NL), Keele University (GB), Swinburne University of Technology (AU), Massachusetts Institute of Technology (US), East Stroudsburg University (US), The University of Texas at Austin (US), Nanjing University (CN)
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
Openalex Percentile: Top 23%
Stellar, planetary, and galactic studies
0.99
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