The CARMENES search for exoplanets around M dwarfs. The impact of rotation and magnetic fields on the radial velocity jitter in cool stars

Abstract

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. 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. 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. The median jitter in the CARMENES sample is 3.1 m/s, and it is 2.3 m/s for stars with an upper limit of 2 km/s 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. A jitter floor of 2 m/s dominates in stars with equatorial rotation velocities below 1 km/s. 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 2-4 kG. 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.

References in corpus (39)

• ESPRESSO@VLT -- On-sky performance and first results
• Spectrum radial velocity analyser (SERVAL). High-precision radial velocities and two alternative spectral indicators
• SOAP 2.0: A tool to estimate the photometric and radial velocity variations induced by stellar spots and plages
• Search for exoplanets with the radial-velocity technique: quantitative diagnostics of stellar activity
• The CARMENES search for exoplanets around M dwarfs: Different roads to radii and masses of the target stars
• CARMENES input catalogue of M dwarfs. I. Low-resolution spectroscopy with CAFOS
• Magnetism, rotation, and nonthermal emission in cool stars -- Average magnetic field measurements in 292 M dwarfs
• Prime Focus Spectrograph (PFS) for the Subaru Telescope: Overview, recent progress, and future perspectives
• Magnetic fields of M dwarfs
• A candidate short-period sub-Earth orbiting Proxima Centauri
• Accounting for velocity jitter in planet search surveys
• The CARMENES search for exoplanets around M dwarfs. Stellar atmospheric parameters of target stars with SteParSyn
• Magnetic fields in M dwarfs from the CARMENES survey
• The CARMENES search for exoplanets around M dwarfs. Guaranteed time observations Data Release 1 (2016-2020)
• The magnetic field and multiple planets of the young dwarf AU~Mic
• SPIRou Input Catalog: Activity, Rotation and Magnetic Field of Cool Dwarfs
• Unsigned magnetic flux as a proxy for radial-velocity variations in Sun-like stars
• The HADES RV Programme with HARPS-N@TNG II. Data treatment and simulations
• Astrophysical Insights into Radial Velocity Jitter from an Analysis of 600 Planet-search Stars
• The CARMENES search for exoplanets around M dwarfs. Measuring precise radial velocities in the near infrared: the example of the super-Earth CD Cet b
• The CARMENES search for exoplanets around M dwarfs -- LP 714-47b (TOI 442.01): Populating the Neptune desert
• Mid-to-Late M Dwarfs Lack Jupiter Analogs
• Convective blueshift strengths of 810 F to M solar-type stars
• The CARMENES search for exoplanets around M dwarfs: Convective shift and starspot constraints from chromatic radial velocities
• Constraining atmospheric parameters and surface magnetic fields with $\text{ZeeTurbo}$: an application to SPIRou spectra
• Stellar signal components seen in HARPS and HARPS-N solar radial velocities
• The CARMENES search for exoplanets around M dwarfs: Stable radial-velocity variations at the rotation period of AD~Leonis -- A test case study of current limitations to treating stellar activity
• The HD 260655 system: Two rocky worlds transiting a bright M dwarf at 10 pc
• The CARMENES search for exoplanets around M dwarfs: Benchmarking the impact of activity in high-precision radial velocity measurements
• The IAG spectral atlas of the spatially resolved Sun: Centre-to-limb observations
• Spectral variability of photospheric radiation due to faculae II: Facular contrasts for cool main-sequence stars
• The CARMENES search for exoplanets around M dwarfs. Telluric absorption corrected high S/N optical and near-infrared template spectra of 382 M dwarf stars
• Rotational modulation of spectroscopic Zeeman signatures in low-mass stars
• The CARMENES search for exoplanets around M dwarfs. Diagnostic capabilities of strong K I lines for photosphere and chromosphere
• Unsigned magnetic flux proxy from solar optical intensity spectra
• TOI-1801 b: A temperate mini-Neptune around a young M0.5 dwarf
• TOI-4438 b: a transiting mini-Neptune amenable to atmospheric characterization
• Solar Photospheric Spectrum Microvariability I. Theoretical searches for proxies of radial-velocity jittering
• Properties of F Stars with Stable Radial Velocity Timeseries: A Useful Metric for Selecting Low-jitter F Stars

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