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Optical and near-infrared stellar activity characterization of the early M dwarf Gl 205 with SOPHIE and SPIRou

2023; EDP Sciences; Volume: 673; Linguagem: Inglês

10.1051/0004-6361/202245131

1432-0746

P. Cortés-Zuleta, I. Boisse, Baptiste Klein, Eder Martioli, P. I. Cristofari, A. Antoniadis-Karnavas, J.‐F. Donati, X. Delfosse, Charles Cadieux, N. Heidari, Étienne Artigau, S. Bellotti, X. Bonfıls, A. Carmona, Neil J. Cook, R. F. Díaz, René Doyon, P. Fouqué, C. Moutou, P. Petit, Thomas Vandal, L. Acuña, L. Arnold, N. Astudillo-Defru, V. Bourrier, F. Bouchy, Ryan Cloutier, S. Dalal, M. Deleuil, O. D. S. Demangeon, X. Dumusque, T. Forveille, J. Gomes da Silva, N. Hara, G. Hébrard, S. Hoyer, G. A. J. Hussain, F. Kiefer, J. Morin, A. Santerne, N. C. Santos, D. Segransan, M. Stalport, S. Udry,

Astrophysics and Star Formation Studies

The stellar activity of M dwarfs is the main limitation for discovering and characterizing exoplanets orbiting them since it induces quasi-periodic RV variations. We aim to characterize the magnetic field and stellar activity of the early, moderately active, M dwarf Gl205 in the optical and nIR domains. We obtained high-precision quasi-simultaneous spectra in the optical and nIR with the SOPHIE spectrograph and SPIRou spectropolarimeter between 2019 and 2022. We computed the RVs from both instruments and the SPIRou Stokes V profiles. We used ZDI to map the large-scale magnetic field over the time span of the observations. We studied the temporal behavior of optical and nIR RVs and activity indicators with the Lomb-Scargle periodogram and a quasi-periodic GP regression. In the nIR, we studied the equivalent width of Al I, Ti I, K I, Fe I, and He I. We modeled the activity-induced RV jitter using a multi-dimensional GP regression with activity indicators as ancillary time series. The optical and nIR RVs have similar scatter but nIR shows a more complex temporal evolution. We observe an evolution of the magnetic field topology from a poloidal dipolar field in 2019 to a dominantly toroidal field in 2022. We measured a stellar rotation period of Prot=34.4$\pm$0.5 d in the longitudinal magnetic field. Using ZDI we measure the amount of latitudinal differential rotation (DR) shearing the stellar surface yielding rotation periods of Peq=32.0$\pm$1.8 d at the stellar equator and Ppol=45.5$\pm$0.3 d at the poles. We observed inconsistencies in the activity indicators' periodicities that could be explained by these DR values. The multi-dimensional GP modeling yields an RMS of the RV residuals down to the noise level of 3 m/s for both instruments, using as ancillary time series H$\alpha$ and the BIS in the optical, and the FWHM in the nIR.