Stellar-activity analysis of the nearby M dwarf GJ 526. Multi-dimensional Gaussian-process modelling of RV, FWHM and S-index
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2025
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| author | Stefanov, A. K. Hernández, J. I. González Mascareño, A. Suárez Rebolo, R. Nari, N. Mestre, J. M. Sousa, S. G. Tabernero, H. M. Osorio, M. -R. Zapatero Figueira, P. Faria, J. P. Hobson, M. J. Silva, A. M. Castro-González, A. Santos, N. C. Sozzetti, A. Pepe, F. Cristiani, S. Lavie, B. Martins, C. J. A. P. |
| author_facet | Stefanov, A. K. Hernández, J. I. González Mascareño, A. Suárez Rebolo, R. Nari, N. Mestre, J. M. Sousa, S. G. Tabernero, H. M. Osorio, M. -R. Zapatero Figueira, P. Faria, J. P. Hobson, M. J. Silva, A. M. Castro-González, A. Santos, N. C. Sozzetti, A. Pepe, F. Cristiani, S. Lavie, B. Martins, C. J. A. P. |
| contents | 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 use 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 carry out joint modelling of: (i) stellar rotation in RV, FWHM, and Mount Wilson S-index through Gaussian processes, (ii) long-term trends in these three physical quantities, (iii) RV planetary signals. We constrain the stellar-rotation period to $P_\text{rot}=48.7\pm 0.3$ d, and discover a weak sinusoidal signature in RV, FWHM and S-index of period $P_\text{cyc}=1680^{+50}_{-40}$ d. 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. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2509_03276 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Stellar-activity analysis of the nearby M dwarf GJ 526. Multi-dimensional Gaussian-process modelling of RV, FWHM and S-index Stefanov, A. K. Hernández, J. I. González Mascareño, A. Suárez Rebolo, R. Nari, N. Mestre, J. M. Sousa, S. G. Tabernero, H. M. Osorio, M. -R. Zapatero Figueira, P. Faria, J. P. Hobson, M. J. Silva, A. M. Castro-González, A. Santos, N. C. Sozzetti, A. Pepe, F. Cristiani, S. Lavie, B. Martins, C. J. A. P. Solar and Stellar Astrophysics Earth and Planetary Astrophysics 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 use 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 carry out joint modelling of: (i) stellar rotation in RV, FWHM, and Mount Wilson S-index through Gaussian processes, (ii) long-term trends in these three physical quantities, (iii) RV planetary signals. We constrain the stellar-rotation period to $P_\text{rot}=48.7\pm 0.3$ d, and discover a weak sinusoidal signature in RV, FWHM and S-index of period $P_\text{cyc}=1680^{+50}_{-40}$ d. 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. |
| title | Stellar-activity analysis of the nearby M dwarf GJ 526. Multi-dimensional Gaussian-process modelling of RV, FWHM and S-index |
| topic | Solar and Stellar Astrophysics Earth and Planetary Astrophysics |
| url | https://arxiv.org/abs/2509.03276 |