HADES RV Programme with HARPS-N at TNG XVI. A super-Earth in the habitable zone of the GJ 3998 multi-planet system
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 publi...
| Autores: | , , , , , , , , , , , , , , |
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| Tipo de recurso: | artículo |
| Estado: | Versión publicada |
| Fecha de publicación: | 2025 |
| País: | España |
| Institución: | Consejo Superior de Investigaciones Científicas (CSIC) |
| Repositorio: | DIGITAL.CSIC. Repositorio Institucional del CSIC |
| OAI Identifier: | oai:digital.csic.es:10261/390329 |
| Acceso en línea: | http://hdl.handle.net/10261/390329 |
| Access Level: | acceso abierto |
| Palabra clave: | Techniques: radial velocities Planets and satellites: detection Stars: activity Stars: individual: GJ 3998 |
| Sumario: | 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 Prot = 30.2 ± 0.3 d and discover long-term sinusoidal imprints in RV and the full width at half maximum with a period of Pcyc = 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. |
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