Mass determination of the three long-period Neptune- and sub-Neptune-sized planets transiting TOI-282

TOI-282 is a bright (V = 9.38) F8 main-sequence star known to host three transiting long-period ( P b = 22.9 d, P c = 56.0 d, and P d = 84.3 d) small ( R p ≈ 2–4 R ⊕ ) planets. The orbital period ratio of the two outermost planets, namely TOI-282 c and d, is close to the 3:2 commensurability, suggesting that the planets might be trapped in a mean motion resonance. We combined space-borne photometry from the TESS telescope with high-precision HARPS and ESPRESSO Doppler measurements to refine orbital parameters, measure the planetary masses, and investigate the architecture and evolution of the system. We performed a Markov chain Monte Carlo joint analysis of the transit light curves and radial velocity time series, and carried out a dynamical analysis to model transit timing variations and Doppler measurements along with N -body integration. In agreement with previous results, we found that TOI-282 b, c, and d have radii of R b = 2.69 ± 0.23 R ⊕ , R c = 4.13 −0.14 +0.16 R ⊕ , and R d = 3.11 ± 0.15 R ⊕ , respectively. We measured planetary masses of M b = 6.2 ± 1.6 M ⊕ , M c = 9.2 ± 2.0 M ⊕ , and M d = 5.8 −1.1 +0.9 M ⊕ , which imply mean densities of ρ b = 1.8 −0.6 +0.7 g cm −3 , ρ c = 0.7 ± 0.2 g cm −3 , and ρ d = 1.1 −0.2 +0.3 g cm −3 , respectively. The three planets may be water worlds, making TOI-282 an interesting system for future atmospheric follow-up observations with JWST and ELT.

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Journal
Astronomy and Astrophysics
Published
2025-10-29
DOI
https://doi.org/10.1051/0004-6361/202556791
Primary Topic
Stellar, planetary, and galactic studies
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article
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article

Mass determination of the three long-period Neptune- and sub-Neptune-sized planets transiting TOI-282

S. Redfield, A. M. S. Smith, S. Csizmadia, D. Gandolfi et al.
Astronomy and Astrophysics
Stellar, planetary, and galactic studies
article

Mass determination of the three long-period Neptune- and sub-Neptune-sized planets transiting TOI-282

S. Redfield, A. M. S. Smith, S. Csizmadia, D. Gandolfi, P. Leonardi, G. Nowak, C. M. Persson, Hendrik Schmerling, F. Rodler, A. Bonfanti, L. Visca, J. Livingston, Patricio E. Cubillos, M. Brogi, M. Fridlund, L. Fossati, William D. Cochran, A Barone, E. Pallé
article en

Abstract

TOI-282 is a bright (V = 9.38) F8 main-sequence star known to host three transiting long-period ( P b = 22.9 d, P c = 56.0 d, and P d = 84.3 d) small ( R p ≈ 2–4 R ⊕ ) planets. The orbital period ratio of the two outermost planets, namely TOI-282 c and d, is close to the 3:2 commensurability, suggesting that the planets might be trapped in a mean motion resonance. We combined space-borne photometry from the TESS telescope with high-precision HARPS and ESPRESSO Doppler measurements to refine orbital parameters, measure the planetary masses, and investigate the architecture and evolution of the system. We performed a Markov chain Monte Carlo joint analysis of the transit light curves and radial velocity time series, and carried out a dynamical analysis to model transit timing variations and Doppler measurements along with N -body integration. In agreement with previous results, we found that TOI-282 b, c, and d have radii of R b = 2.69 ± 0.23 R ⊕ , R c = 4.13 −0.14 +0.16 R ⊕ , and R d = 3.11 ± 0.15 R ⊕ , respectively. We measured planetary masses of M b = 6.2 ± 1.6 M ⊕ , M c = 9.2 ± 2.0 M ⊕ , and M d = 5.8 −1.1 +0.9 M ⊕ , which imply mean densities of ρ b = 1.8 −0.6 +0.7 g cm −3 , ρ c = 0.7 ± 0.2 g cm −3 , and ρ d = 1.1 −0.2 +0.3 g cm −3 , respectively. The three planets may be water worlds, making TOI-282 an interesting system for future atmospheric follow-up observations with JWST and ELT.

Astronomy and AstrophysicsVol. 704
Wesleyan University (US), Leiden University (NL), Austrian Academy of Sciences (AT), University of Padua (IT), University of Cologne (DE), University of Trento (IT), The Graduate University for Advanced Studies, SOKENDAI (JP), Istituto Nazionale di Fisica Nucleare, Galileo Galilei Institute for Theoretical Physics (IT), Deutsches Zentrum für Luft- und Raumfahrt e. V. (DLR) (DE), Osservatorio Astrofisico di Torino (IT), Planetary Systems (United States) (US), Astrobiology Center (JP), Rhenish Institute for Environmental Research (DE), Institute of Astronomy (RU), Instituto de Astrofísica de Canarias (ES), Nicolaus Copernicus Astronomical Center (PL), National Astronomical Observatory of Japan (JP), Leiden Observatory, University of Turin (IT), Chalmers University of Technology (SE), The University of Texas at Austin (US)
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Stellar, planetary, and galactic studies
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