The CARMENES search for exoplanets around M dwarfs. Line-by-line sensitivity to activity in M dwarfs

Abstract

Radial velocities (RVs) measured from high-resolution stellar spectra are routinely used to detect and characterise orbiting exoplanet companions. The different lines present in stellar spectra are created by several species, which are non-uniformly affected by stellar variability features such as spots or faculae. Stellar variability distorts the shape of the spectral absorption lines from which precise RVs are measured, posing one of the main problems in the study of exoplanets. In this work we aim to study how the spectral lines present in M dwarfs are independently impacted by stellar activity. We used CARMENES optical spectra of six active early- and mid-type M dwarfs to compute line-by-line RVs and study their correlation with several well-studied proxies of stellar activity. We are able to classify spectral lines based on their sensitivity to activity in five M dwarfs displaying high levels of stellar activity. We further used this line classification to compute RVs with activity-sensitive lines and less sensitive lines, enhancing or mitigating stellar activity effects in the RV time series. For specific sets of the least activity-sensitive lines, the RV scatter decreases by ~ 2 to 5 times the initial one, depending on the star. Finally, we compare these lines in the different stars analysed, finding the sensitivity to activity to vary from star to star. Despite the high density of lines and blends present in M dwarf stellar spectra, we find that a line-by-line approach is able to deliver precise RVs. Line-by-line RVs are also sensitive to stellar activity effects, and they allow for an accurate selection of activity-insensitive lines to mitigate activity effects in RV. However, we find stellar activity effects to vary in the same insensitive lines from star to star.

arXiv commentAccepted for publication in A&A

References in corpus (64)

• The generalised Lomb-Scargle periodogram. A new formalism for the floating-mean and Keplerian periodograms
• No planet for HD 166435
• The CORALIE survey for southern extra-solar planets VII. Two short-period Saturnian companions to HD108147 and HD168746
• Spectrum radial velocity analyser (SERVAL). High-precision radial velocities and two alternative spectral indicators
• Large-scale magnetic topologies of mid-M dwarfs
• The HARPS-TERRA project I. Description of the algorithms, performance and new measurements on a few remarkable stars observed by HARPS
• The HARPS search for southern extra-solar planets. X. A m sin i = 11 Mearth planet around the nearby spotted M dwarf GJ 674
• The CARMENES search for exoplanets around M dwarfs: High-resolution optical and near-infrared spectroscopy of 324 survey stars
• 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
• Measuring precise radial velocities on individual spectral lines. I. Validation of the method and application to mitigate stellar activity
• SPIRou: nIR velocimetry & spectropolarimetry at the CFHT
• The CARMENES search for exoplanets around M dwarfs. First visual-channel radial-velocity measurements and orbital parameter updates of seven M-dwarf planetary systems
• EXPRES: A Next Generation RV Spectrograph in the Search for Earth-like Worlds
• Using the Sun to estimate Earth-like planets detection capabilities.I. Impact of cold spots
• Flat-relative optimal extraction. A quick and efficient algorithm for stabilised spectrographs
• Evidence for solar-like oscillations in beta Hydri
• The HARPS search for southern extra-solar planets XXXV. The interesting case of HD41248: stellar activity, no planets?
• Correcting HIRES radial velocities for small systematic errors
• CARMENES input catalogue of M dwarfs IV. New rotation periods from photometric time series
• The CARMENES search for exoplanets around M dwarfs. Activity indicators at visible and near-infrared wavelengths
• Line-by-line velocity measurements, an outlier-resistant method for precision velocimetry
• Measuring precise radial velocities on individual spectral lines : II. Dependance of stellar activity signal on line depth
• The IAG solar flux atlas: Accurate wavelengths and absolute convective blueshift in standard solar spectra
• Magnetic fields in M dwarfs from the CARMENES survey
• The CARMENES search for exoplanets around M dwarfs -- Photospheric parameters of target stars from high-resolution spectroscopy. II. Simultaneous multiwavelength range modeling of activity insensitive lines
• XID II: Statistical Cross-Association of ROSAT Bright Source Catalog X-ray Sources with 2MASS Point Source Catalog Near-Infrared Sources
• The CARMENES search for exoplanets around M dwarfs. Radial velocities and activity indicators from cross-correlation functions with weighted binary masks
• The CARMENES search for exoplanets around M dwarfs: Radial-velocity variations of active stars in visual-channel spectra
• Three-dimensional simulations of near-surface convection in main-sequence stars - II. Properties of granulation and spectral lines
• Activity-induced radial velocity jitter in a flaring M dwarf
• Variability of stellar granulation and convective blueshift with spectral type and magnetic activity. I. K and G main sequence stars
• How magnetic activity alters what we learn from stellar spectra
• Likely Members of the Beta Pictoris and AB Doradus Moving Groups in the North
• The GAPS Programme at TNG XXI -- A GIARPS case-study of known young planetary candidates: confirmation of HD 285507 b and refutation of AD Leo b
• Stellar Surface Magneto-Convection as a Source of Astrophysical Noise II. Center-to-Limb Parameterisation of Absorption Line Profiles and Comparison to Observations
• Insights on the Spectral Signatures of Stellar Activity and Planets from PCA
• The EXPRES Stellar Signals Project II. State of the Field in Disentangling Photospheric Velocities
• New Methods for Finding Activity-Sensitive Spectral Lines: Combined Visual Identification and an Automated Pipeline Find a Set of 40 Activity Indicators
• TOI-1452 b: SPIRou and TESS reveal a super-Earth in a temperate orbit transiting an M4 dwarf
• Reaching the boundary between stellar kinematic groups and very wide binaries. III. Sixteen new stars and eight new wide systems in the beta Pictoris moving group
• Measuring precise radial velocities on individual spectral lines. III. Dependence of stellar activity signal on line formation temperature
• The Changing Face of $\alpha$ Centauri B: Probing plage and stellar activity in K-dwarfs
• The CARMENES search for exoplanets around M dwarfs. Mapping stellar activity indicators across the M dwarf domain
• Convective blueshift strengths of 810 F to M solar-type stars
• Persistent starspot signals on M dwarfs: multi-wavelength Doppler observations with the Habitable-zone Planet Finder and Keck/HIRES
• The CARMENES search for exoplanets around M dwarfs: Convective shift and starspot constraints from chromatic radial velocities
• Orbital misalignment of the super-Earth $\pi$ Men c with the spin of its star
• TOI-1759 b: a transiting sub-Neptune around a low mass star characterized with SPIRou and TESS
• 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 CARMENES search for exoplanets around M dwarfs: Benchmarking the impact of activity in high-precision radial velocity measurements
• AD Leonis: Radial velocity signal of stellar rotation or spin-orbit resonance?
• Estimating the p-mode frequencies of the solar twin 18 Sco
• The CARMENES search for exoplanets around M dwarfs: Not-so-fine hyperfine-split vanadium lines in cool star spectra
• The CARMENES search for exoplanets around M dwarfs: Rubidium abundances in nearby cool stars
• Mitigating stellar activity jitter with different line lists for least-squares deconvolution: analysis of a parametric and a randomised line selection
• TESS discovery of a sub-Neptune orbiting a mid-M dwarf TOI-2136
• The CARMENES search for exoplanets around M dwarfs. Rotational variation in activity indicators of Ross 318, YZ CMi, TYC 3529-1437-1, and EV Lac
• HADES RV Programme with HARPS-N at TNG VI. GJ 3942 b behind dominant activity signals
• Revisiting Radial Velocity Measurements of the K2-18 System with the Line-by-Line Framework
• Activity and telluric contamination in HARPS observations of Alpha Centauri B
• Stellar masks and bisector's shape for M-type stars observed in the GAPS Programme with HARPS-N at TNG
• Into the Depths: a new activity metric for high-precision radial velocity measurements based on line depth variations

Cited by in corpus (2)

• The Effects of Sunspots on Spectral Line Shapes in the Visible
• TILARA: Template-Independent Line-by-line Algorithm for Radial velocity Analysis. I. Description of the code and application on a Sun-like star