HADES RV Programme with HARPS-N at TNG
The low masses of M dwarfs create attractive opportunities for exoplanet radial-velocity (RV) detections. These stars, however, exhibit strong stellar activity that may attenuate or mimic planetary signals. We present a velocimetric analysis of one such M dwarf, GJ 3998 ( d = 18.2 pc), with two published short-period super-Earths: GJ 3998 b and GJ 3998 c. We use additional data from the HARPS-N spectrograph to confirm these two planets and to look for more. We carry out joint modelling of: (i) RV planetary signals, (ii) stellar rotation in RV and activity indicators through Gaussian processes, and (iii) long-term trends in RV and activity indicators. We constrain the rotational period of GJ 3998 to P rot = 30.2 ± 0.3 d and discover long-term sinusoidal imprints in RV and the full width at half maximum with a period of P cyc = 316 −8 +14 d. We confirm GJ 3998 b and GJ 3998 c, and detect a third planet: GJ 3998 d, whose signal had previously been attributed to stellar activity. GJ 3998 d has an orbital period of 41.78 ± 0.05 d, a minimum mass of 6.07 −0.96 +1.00 M ⊕ , and a mean insolation flux of 1.2 −0.2 +0.3 Φ ⊕ . This makes it one of the few known planets receiving an Earth-like insolation flux.
Authors
- N. Nari (ORCID: https://orcid.org/0009-0001-2825-6185)
- M. Pinamonti (ORCID: https://orcid.org/0000-0002-4445-1845)
- G. Micela (ORCID: https://orcid.org/0000-0002-9900-4751)
- J. Maldonado (ORCID: https://orcid.org/0000-0002-2218-5689)
- A. Suárez Mascareño (ORCID: https://orcid.org/0000-0002-3814-5323)
- Alessandro Sozzetti (ORCID: https://orcid.org/0000-0002-7504-365X)
- M. Damasso (ORCID: https://orcid.org/0000-0001-9984-4278)
- I. Ribas (ORCID: https://orcid.org/0000-0002-6689-0312)
- M. Perger (ORCID: https://orcid.org/0000-0001-7098-0372)
- R. Rébolo (ORCID: https://orcid.org/0000-0003-3767-7085)
- E. González-Álvarez (ORCID: https://orcid.org/0000-0002-4820-2053)
- A. K. Stefanov (ORCID: https://orcid.org/0000-0002-6059-1178)
- J. I. Gónzalez Hernández (ORCID: https://orcid.org/0000-0002-0264-7356)
- L. Affer (ORCID: https://orcid.org/0000-0001-5600-3778)
- G. Scandriato (ORCID: https://orcid.org/0000-0003-2029-0626)
Institutions
- Universidad de Las Palmas de Gran Canaria (ES)
- Universidad Complutense de Madrid (ES)
- Institute of Space Sciences (ES)
- Consejo Superior de Investigaciones Científicas (ES)
- Universidad de La Laguna (ES)
- Institut d'Estudis Espacials de Catalunya (ES)
- Osservatorio Astrofisico di Torino (IT)
- Osservatorio Astrofisico di Catania (IT)
- Osservatorio Astronomico di Palermo (IT)
- Instituto de Astrofísica de Canarias (ES)
Publication Details
- Journal
- Astronomy and Astrophysics
- Published
- 2025-02-05
- DOI
- https://doi.org/10.1051/0004-6361/202452630
- Citations
- 3
- Primary Topic
- Stellar, planetary, and galactic studies
- Type
- article
- Field-Weighted Citation Impact
- 3.46
Funders
- “la Caixa” Foundation
- Ministerio de Ciencia, Innovación y Universidades
- Universidad Complutense de Madrid
- Ministerio de Ciencia e Innovación
- Ministero dell'Università e della Ricerca
- HORIZON EUROPE European Research Council