The CARMENES search for exoplanets around M dwarfs

Context. Radial velocity (RV) jitter represents an intrinsic limitation on the precision of Doppler searches for exoplanets that can originate from both instrumental and astrophysical sources. Aims. We aim to determine the RV jitter floor in M dwarfs and investigate the stellar properties that lead to RV jitter induced by stellar activity. Methods. We determined the RV jitter in 239 M dwarfs from the CARMENES survey that are predominantly of mid to late spectral type and solar metallicity. We also investigated the correlation between stellar rotation and magnetic fields with RV jitter. Results. The median jitter in the CARMENES sample is 3.1 m s −1 , and it is 2.3 m s −1 for stars with an upper limit of 2 km s −1 on their projected rotation velocities. We provide a relation between the stellar equatorial rotation velocity and RV jitter in M dwarfs based on a subsample of 129 well-characterized CARMENES stars. RV jitter induced by stellar rotation dominates for stars with equatorial rotation velocities greater than 1 km s −1 . A jitter floor of 2 m s −1 dominates in stars with equatorial rotation velocities below 1 km s −1 . This jitter floor likely contains contributions from stellar jitter, instrumental jitter, and undetected companions. We study the impact of the average magnetic field and the distributions of magnetic filling factors on the RV jitter. We find a series of stars with excess RV jitter and distinctive distributions of magnetic filling factors. These stars are characterized by a dominant magnetic field component between 2 to 4 kG. Conclusions. An RV jitter floor can be distinguished from RV jitter induced by activity and rotation based on the stellar equatorial rotation velocity. RV jitter induced by activity and rotation primarily depends on the equatorial rotation velocity. This RV jitter is also related to the distribution of magnetic filling factors, and this emphasizes the role of the magnetic field in the generation of RV jitter.

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Publication Details

Journal
Astronomy and Astrophysics
Published
2024-12-01
DOI
https://doi.org/10.1051/0004-6361/202450836
Citations
4
Primary Topic
Stellar, planetary, and galactic studies
Type
article
Field-Weighted Citation Impact
1.33

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article

The CARMENES search for exoplanets around M dwarfs

A. Reiners, P. Schöfer, H. L. Ruh, A. Quirrenbach et al.
4 citations
Astronomy and Astrophysics
Stellar, planetary, and galactic studies
1.33
article

The CARMENES search for exoplanets around M dwarfs

A. Reiners, P. Schöfer, H. L. Ruh, A. Quirrenbach, J. A. Caballero, P. J. Amado, J. Aceituno, E. Nagel, S. V. Jeffers, A. P. Hatzes, I. Ribas, V. J. S. Béjar, R. Varas, D. Montes, A. Schweitzer, M. Zechmeister, L. Tal-Or, J. C. Morales, C. Cifuentes, A. Kaminski, Th. Henning, Y. Shan
article en
4 citations

Abstract

Context. Radial velocity (RV) jitter represents an intrinsic limitation on the precision of Doppler searches for exoplanets that can originate from both instrumental and astrophysical sources. Aims. We aim to determine the RV jitter floor in M dwarfs and investigate the stellar properties that lead to RV jitter induced by stellar activity. Methods. We determined the RV jitter in 239 M dwarfs from the CARMENES survey that are predominantly of mid to late spectral type and solar metallicity. We also investigated the correlation between stellar rotation and magnetic fields with RV jitter. Results. The median jitter in the CARMENES sample is 3.1 m s −1 , and it is 2.3 m s −1 for stars with an upper limit of 2 km s −1 on their projected rotation velocities. We provide a relation between the stellar equatorial rotation velocity and RV jitter in M dwarfs based on a subsample of 129 well-characterized CARMENES stars. RV jitter induced by stellar rotation dominates for stars with equatorial rotation velocities greater than 1 km s −1 . A jitter floor of 2 m s −1 dominates in stars with equatorial rotation velocities below 1 km s −1 . This jitter floor likely contains contributions from stellar jitter, instrumental jitter, and undetected companions. We study the impact of the average magnetic field and the distributions of magnetic filling factors on the RV jitter. We find a series of stars with excess RV jitter and distinctive distributions of magnetic filling factors. These stars are characterized by a dominant magnetic field component between 2 to 4 kG. Conclusions. An RV jitter floor can be distinguished from RV jitter induced by activity and rotation based on the stellar equatorial rotation velocity. RV jitter induced by activity and rotation primarily depends on the equatorial rotation velocity. This RV jitter is also related to the distribution of magnetic filling factors, and this emphasizes the role of the magnetic field in the generation of RV jitter.

Astronomy and AstrophysicsVol. 692
Universidad Complutense de Madrid (ES), Institute of Space Sciences (ES), Universidad de La Laguna (ES), Universität Hamburg (DE), University of Oslo (NO), Heidelberg University (DE), Calar Alto Observatory (ES), Institut d'Estudis Espacials de Catalunya (ES), Max Planck Institute for Astronomy (DE), Institute of Space Sciences (ES), Max Planck Institute for Solar System Research (DE), Centro de Astrobiología (ES), Instituto de Astrofísica de Canarias (ES), Institut de Ciència de Materials de Barcelona (ES), Thüringer Landessternwarte Tautenburg (DE), Instituto de Astrofísica de Andalucía (ES), Ariel University (IL), University of Göttingen (DE)
Centres de Recerca de Catalunya, Deutsche Forschungsgemeinschaft, Generalitat de Catalunya, Universidad Complutense de Madrid, Ministerio de Economía y Competitividad, Max-Planck-Gesellschaft, Ministerio de Ciencia e Innovación, Klaus Tschira Stiftung, Junta de Andalucía, Instituto de Astrofísica de Andalucía, Max-Planck-Institut für Astronomie, Instituto de Astrofísica de Canarias, Consejo Superior de Investigaciones Científicas, European Regional Development Fund, Agencia Estatal de Investigación
Openalex Percentile: Top 19%
Stellar, planetary, and galactic studies
1.33
DOIOpen Access PDFOpenAlex
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