Mass determination of the three long-period Neptune- and sub-Neptune-sized planets transiting TOI-282
Journal article, 2025
TOI-282 is a bright (V = 9.38) F8 main-sequence star known to host three transiting long-period (Pb = 22.9 d, Pc = 56.0 d, and Pd = 84.3 d) small (Rp ≈ 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 Rb = 2.69 ± 0.23 R⊕, Rc = 4.13-0.14+0.16 R⊕, and Rd = 3.11 ± 0.15 R⊕, respectively. We measured planetary masses of Mb = 6.2 ± 1.6 M⊕, Mc = 9.2 ± 2.0 M⊕, and Md = 5.8-1.1+0.9 M⊕, which imply mean densities of ρb = 1.8-0.6+0.7 g cm-3, ρc = 0.7 ± 0.2 g cm-3, and ρd = 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.
Planets and satellites: dynamical evolution and stability
Planets and satellites: composition
Planets and satellites: physical evolution
Planets and satellites: fundamental parameters
Planets and satellites: general
Author
A. Barone
University of Turin
Institut fur Weltraumforschung
F. Rodler
European Southern Observatory Santiago
D. Gandolfi
University of Turin
A. Bonfanti
Institut fur Weltraumforschung
P. Leonardi
University of Trento
University of Padua
L. Visca
University of Turin
Malcolm Fridlund
Leiden University
Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics
M. Brogi
University of Turin
Istituto nazionale di astrofisica (INAF)
L. Fossati
Institut fur Weltraumforschung
P. E. Cubillos
Istituto nazionale di astrofisica (INAF)
Institut fur Weltraumforschung
William D. Cochran
The University of Texas at Austin
Szilard Csizmadia
German Aerospace Center (DLR)
J.H. Livingston
National Astronomical Observatory of Japan
National Institutes of Natural Sciences
The Graduate University for Advanced Studies (SOKENDAI)
G. Nowak
Nicolaus Copernicus University (SGMK)
Enric Palle
Instituto de Astrofísica de Canarias
University of La Laguna
Carina Persson
Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics
S. Redfield
Wesleyan University
H. Schmerling
University of Cologne
A. M.S. Smith
German Aerospace Center (DLR)
Astronomy and Astrophysics
0004-6361 (ISSN) 1432-0746 (eISSN)
Vol. 704 A41Subject Categories (SSIF 2025)
Astronomy, Astrophysics, and Cosmology
DOI
10.1051/0004-6361/202556791