A. K. Stefanov, J. I. González Hernández, A. Suárez Mascareño, R. Rebolo, N. Nari, J. M. Mestre, S. G. Sousa, H. M. Tabernero, M. R. Zapatero Osorio, P. Figueira, J. P. Faria, M. J. Hobson, A. M. Silva, A. Castro-González, N. C. Santos, A. Sozzetti, F. Pepe, S. Cristiani, B. Lavie, C. J. A. P. Martins
Abstract
M dwarfs are the most abundant stars in the Galaxy, and their low masses make them natural favourites for exoplanet radial-velocity (RV) searches. Nevertheless, these stars often demonstrate strong stellar activity that is yet to be fully understood. We used high-precision ESPRESSO, HIRES, and HARPS spectroscopy to perform a stellar-activity analysis on the nearby early M dwarf GJ 526 (d = 5.4 pc). We carried out a joint modelling of (i) the stellar rotation in RV, full width at half maximum (FWHM), and Mount Wilson S-index through Gaussian processes; (ii) long-term trends in these three physical quantities; and (iii) RV planetary signals. We constrained the stellar-rotation period to Prot = 48.7 ± 0.3 d, and discovered a weak sinusoidal signature in RV, FWHM, and S-index of period Pcyc = 1680−40+50d. We propose phase-space trajectories between RV and activity indicators as a novel means to visualise and interpret stellar activity. Current evidence does not support planetary companions of GJ 526.
Keywords
techniques: radial velocities / stars: activity / stars: low-mass / stars: individual: GJ 526
Astronomy & Astrophysics
Volume 703, Article Number a245, Number of pages 19
2025 November
