P. Lamontagne, D. Weisserman, C. Cadieux, D. Lafreniere, A. L'Heureux, M. Plotnykov, L. Parc, A. K. Stefanov, L. Moranta, R. Doyon, F. Bouchy, J.-B. Delisle, L. D. Nielsen, G. Lo Curto, F. Baron, S. C. C. Barros, B. Benneke, X. Bonfils, M. Bryan, B. L. Canto Martins, R. Cloutier, N. B. Cowan, D. B. de Freitas, J. R. de Medeiros, X. Delfosse, E. Delgado-Mena, X. Dumusque, D. Ehrenreich, P. Figueira, J. I. González Hernández, I. de Castro Leao, C. Lovis, L. Malo, C. Melo, L. Mignon, C. Mordasini, F. Pepe, R. Rebolo, J. Rowe, N. C. Santos, D. Segransan, A. Suarez Mascareno, S. Udry, D. Valencia, G. A. Wade, M. Abreu, J. L. A. Aguiar, K. Al Moulla, G. Allain, R. Allart, J. -M. Almenara, T. Arial, H. Auger, L. Bazinet, N. Blind, D. Bohlender, E. Artigau, I. Boisse, A. Boucher, V. Bourrier, S. Bovay, P. M. H. Branco, C. H. Broeg, D. Brousseau, A. Cabral, A. Carmona, Y. Carteret, Z. Challita, D. Charbonneau, B. Chazelas, C. A. Clark, J. Coelho, M. Cointepas, K. I. Collins, K. A. Collins, U. Conod, E. A. S. Cristo, A. R. Costa Silva, A. Darveau-Bernier, L. Dauplaise, R. de Lima Gomes, J. P. Faria, D. O. Fontinele, T. Forveille, Y. G. C. Frensch, J. Gagne, F. Genest, L. Genolet, J. Gomes da Silva, F. Gracia Temich, N. Gromek, N. Grieves, O. Hernandez, M. Hobson, H. J. Hoeijmakers, N. Hubin, N. J. Cook, M. Jafariyazani, F. Jahandar, R. Jayawardhana, H. Kaufl, D. Kerley, J. Kolb, V. Krishnamurthy, B. Kung, P. Larue, H. Leath, O. Lim, A. M. Martins, E. C. Matthews, J. Matthews, J. Mayer, S. Metchev, L. Messamah, Y. Messias, D. Mounzer, N. Nari, A. Osborn, M. Ouellet, J. Otegi, L. Pasquini, V. M. Passegger, S. Pelletier, C. Peroux, C. Piaulet-Ghorayeb, E. Pompei, A.-S. Poulin-Girard, J. L. Rasilla, V. Reshetov, J. Saint-Antoine, M. Sarajlic, I. Saviane, R. Schnell, A. Segovia, J. V. Seidel, A. Silber, P. Sinclair, M. Sordet, D. Sosnowska, A. Srivastava, M. A. Teixeira, S. Thibault, P. Vallee, T. Vandal, V. Vaulato, J. P. Wardenier, B. Wehbe, I. Wevers, F. Wildi, V. Yariv, G. Zins
Abstract
We present an updated characterization of the planetary system orbiting the nearby M2 dwarf GJ 3090 (TOI-177; d=22 pc), based on new high-precision radial velocity (RV) observations from NIRPS and HARPS. With an orbital period of 2.85 d, the transiting sub-Neptune GJ 3090 b has a mass we refine to 4.52 ± 0.47 M⊕, which, combined with our derived radius of 2.18 ± 0.06 R⊕, yields a density of 2.40−0.30+0.33 g∉cm−3. The combined interior structure and atmospheric constraints indicate that GJ 3090 b is a compelling water-world candidate, with a volatile-rich envelope in which water likely represents a significant fraction. We also confirm the presence of a second planet, GJ 3090 c, a sub-Neptune with a 15.9 d orbit and a minimum mass of 10.0 ± 1.3 M⊕, which does not transit. Despite its proximity to the star's 18 d rotation period, our joint analysis using a multidimensional Gaussian process (GP) model that incorporates TESS photometry and differential stellar temperature measurements distinguishes this planetary signal from activity-induced variability. In addition, we place new constraints on a non-transiting planet candidate with a period of 12.7 d, suggested in earlier RV analyses. This candidate remains a compelling target for future monitoring. These results highlight the crucial role of multidimensional GP modelling in disentangling planetary signals from stellar activity, enabling the detection of a planet near the stellar rotation period that could have remained undetected with traditional approaches.
Keywords
instrumentation: spectrographs / planets and satellites: detection / planets and satellites: dynamical evolution and stability / planets and satellites: fundamental parameters / planet-star interactions
Astronomy & Astrophysics
Volume 706, Article Number A278, Number of pages 26
2026 February
