Search for exoplanets with the radial-velocity technique: quantitative diagnostics of stellar activity

Abstract

Aims: Stellar activity may complicate the analysis of high-precision radial-velocity spectroscopic data when looking for exoplanets signatures. We aim at quantifying the impact of stellar spots on stars with various spectral types and rotational velocities and comparing the simulations with data obtained with the HARPS spectrograph. Methods: We have developed detailed simulations of stellar spots and estimated their effects on a number of observables commonly used in the analysis of radial-velocity data when looking for extrasolar planets, such as radial-velocity curves, cross-correlation functions, bisector spans and photometric curves. The computed stellar spectra are then analyzed in the same way as when searching for exoplanets. Results: 1) A first grid of simulation results is built for F-K type stars, with different stellar and spot properties. 2) It is shown quantitatively that star spots with typical sizes of 1% can mimic both radial-velocity curves and the bisector behavior of short-period giant planets around G-K type stars with a vsini lower than the spectrograph resolution. For stars with intermediate vsini, smaller spots may produce similar features. In these cases, additional observables (e.g., photometry, spectroscopic diagnostics) are mandatory to confirm the presence of short-period planets. We show that, in some cases, photometric variations may not be enough to clearly rule out spots as explanations of the observed radial-velocity variations. This is particularly important when searching for super-Earth planets. 3) It is also stressed that quantitative values obtained for radial-velocity and bisector span amplitudes depend strongly on the detailed star properties, on the spectrograph used, on the set of lines used, and on the way they are measured.

12 pages, 16 figures, accepted for publication in A&A

References in corpus (8)

• The Geneva-Copenhagen survey of the Solar neighbourhood: Ages, metallicities, and kinematic properties of 14,000 F and G dwarfs
• No planet for HD 166435
• Contributions to the Nearby Stars (NStars) Project: Spectroscopy of Stars Earlier than M0 within 40 parsecs: The Northern Sample I
• Extrasolar planets and brown dwarfs around A-F type stars. I. Performances of radial velocity measurements, first analyses of variations
• Searching for Planets in the Hyades V: Limits on Planet Detection in the Presence of Stellar Activity
• Extrasolar planets and brown dwarfs around A-F type stars. II. A planet found with ELODIE around the F6V star HD 33564
• Exoplanets or Dynamic Atmospheres? The Radial Velocity and Line Shape Variations of 51 Pegasi and Tau Bootis
• Extrasolar planets and brown dwarfs around A-F type stars III. Beta-Pictoris : looking for planets, finding pulsations

Cited by in corpus (149)

• Planets and Stellar Activity: Hide and Seek in the CoRoT-7 system
• Spectrum radial velocity analyser (SERVAL). High-precision radial velocities and two alternative spectral indicators
• State of the Field: Extreme Precision Radial Velocities
• A temperate rocky super-Earth transiting a nearby cool star
• Using the Sun to estimate Earth-like planets detection capabilities II. Impact of plages
• SOAP 2.0: A tool to estimate the photometric and radial velocity variations induced by stellar spots and plages
• The CARMENES search for exoplanets around M dwarfs: High-resolution optical and near-infrared spectroscopy of 324 survey stars
• CERES: A Set of Automated Routines for Echelle Spectra
• Detecting Planets Around Very Low Mass Stars with the Radial Velocity Method
• WASP-19b: the shortest period transiting exoplanet yet discovered
• A High-Precision NIR Survey for RV Variable Low-Mass Stars
• Measuring precise radial velocities on individual spectral lines. I. Validation of the method and application to mitigate stellar activity
• The Sun as a planet-host star: Proxies from SDO images for HARPS radial-velocity variations
• Determining the Mass of Kepler-78b With Nonparametric Gaussian Process Estimation
• SOAP. A tool for the fast computation of photometry and radial velocity induced by stellar spots
• Using the Sun to estimate Earth-like planets detection capabilities.I. Impact of cold spots
• CARMENES input catalogue of M dwarfs: III. Rotation and activity from high-resolution spectroscopic observations
• A candidate short-period sub-Earth orbiting Proxima Centauri
• Extrasolar planets and brown dwarfs around A-F type stars VI. High precision RV survey of early type dwarfs with HARPS
• Instrumentation for the detection and characterization of exoplanets
• Chromospheric activity and rotation of FGK stars in the solar vicinity. An estimation of the radial velocity jitter
• HD 285507b: An Eccentric Hot Jupiter in the Hyades Open Cluster
• The HARPS search for southern extra-solar planets. XXXVIII. Bayesian re-analysis of three systems. New super-Earths, unconfirmed signals, and magnetic cycles
• Three Years of HARPS-N High-Resolution Spectroscopy and Precise Radial Velocity Data for the Sun
• A Candidate Young Massive Planet in Orbit around the Classical T Tauri Star CI Tau
• Modeling the RV jitter of early M dwarfs using tomographic imaging
• Evidence against the young hot-Jupiter around BD +20 1790
• Color difference makes a difference: four planet candidates around tau Ceti
• The HARPS search for southern extra-solar planets XXXV. Super-Earths around the M-dwarf neighbors Gl433 and Gl667C
• Radial velocity signatures of Zeeman broadening
• Line-profile variations in radial-velocity measurements: Two alternative indicators for planetary searches
• The effect of M dwarf starspot activity on low-mass planet detection thresholds
• Characterisation of the radial velocity signal induced by rotation in late-type dwarfs
• A Young Planet Search in Visible and IR Light: DN Tau, V836 Tau, and V827 Tau
• Photospheric activity, rotation, and radial velocity variations of the planet-hosting star CoRoT-7
• Stellar activity as noise in exoplanet detection II. Application to M dwarfs
• The GJ 504 system revisited. Combining interferometric, radial velocity, and high contrast imaging data
• Characterization of the L 98-59 multi-planetary system with HARPS: two confirmed terrestrial planets and a mass upper limit on the third
• Using the Sun to estimate Earth-like planets detection capabilities. V. Parameterizing the impact of solar activity components on radial velocities
• A Search for Giant Planet Companions to T Tauri Stars
• Modelling the photosphere of active stars for planet detection and characterization
• Diving Beneath the Sea of Stellar Activity: Chromatic Radial Velocities of the Young AU Mic Planetary System
• Planetary-mass companions to the K-giants BD+15 2940 and HD 233604
• The HARPS search for southern extra-solar planets. XXXVI. Eight HARPS multi-planet systems hosting 20 super-Earth and Neptune-mass companions
• Activity-induced radial velocity jitter in a flaring M dwarf
• Radial Velocity Fitting Challenge. I. Simulating the data set including realistic stellar radial-velocity signals
• Stellar activity with LAMOST. I. Spot configuration in Pleiades
• The NASA-UC Eta-Earth Program: II. A Planet Orbiting HD 156668 with a Minimum Mass of Four Earth Masses
• Starspot-induced optical and infrared radial velocity variability in T Tauri star Hubble 4
• 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
• HD 135344B: a young star has reached its rotational limit
• Radial Velocities with CRIRES: Pushing precision down to 5-10 m/s
• The EXPRES Stellar Signals Project II. State of the Field in Disentangling Photospheric Velocities
• A giant planet in the triple system HD132563
• The CARMENES search for exoplanets around M dwarfs. Three temperate to warm super-Earths
• Transit timing variation and activity in the WASP-10 planetary system
• The CARMENES search for exoplanets around M dwarfs. A Neptune-mass planet traversing the habitable zone around HD 180617
• ROPS: A New Search for Habitable Earths in the Southern Sky
• Search for associations containing young stars (SACY) VIII. An updated census of spectroscopic binary systems showing hints of non-universal multiplicity among these associations
• The GAPS programme with HARPS-N@TNG IV: A planetary system around XO-2S
• Deriving the radial-velocity variations induced by stellar activity from high-precision photometry - Test on HD189733 with simultaneous MOST/SOPHIE data
• Planets around stars in young nearby associations *** radial Velocity searches: a feasibility study, and first results
• The CARMENES search for exoplanets around M dwarfs. Mapping stellar activity indicators across the M dwarf domain
• The CARMENES search for exoplanets around M dwarfs: Convective shift and starspot constraints from chromatic radial velocities
• Extrasolar planets and brown dwarfs around AF-type stars. IX. The HARPS southern sample
• Unexpectedly strong effect of supergranulation on the detectability of Earth twins orbiting Sun-like stars with radial velocities
• Precision radial velocities with CSHELL
• Starspot occultations in infrared transit spectroscopy: the case of WASP-52b
• Extrasolar planets and brown dwarfs around AF-type stars. X.The SOPHIE northern sample. Combining the SOPHIE and HARPS surveys to compute the close giant planet mass-period distribution around AF-type stars
• The correlation between photometric variability and radial velocity jitter, based on TESS and HARPS observations
• Stellar Activity and Exclusion of the Outer Planet in the HD 99492 System
• The Impact of Stellar Surface Magnetoconvection and Oscillations on the Detection of Temperate, Earth-Mass Planets Around Sun-Like Stars
• Multi-band high resolution spectroscopy rules out the hot Jupiter BD+20 1790b - First data from the GIARPS Commissioning
• 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
• A HARPS RV search for planets around young nearby stars
• Activity time series of old stars from late F to early K. I. Simulating radial velocity, astrometry, photometry, and chromospheric emission
• A new method of correcting radial velocity time series for inhomogeneous convection
• The HARPS search for southern extra-solar planets XXXVI: Five new long-period giant planets and a system update
• A vigorous activity cycle mimicking a planetary system in HD200466
• Extrasolar planets and brown dwarfs around A--F type stars. VIII. A giant planet orbiting the young star HD113337
• The GAPS Programme with HARPS-N at TNG XVII. Line profile indicators and kernel regression as diagnostics of radial-velocity variations due to stellar activity in solar-like stars
• Analysis of combined radial velocities and activity of BD+20 1790: evidence supporting the existence of a planetary companion
• The first super-Earth Detection from the High Cadence and High Radial Velocity Precision Dharma Planet Survey
• Evidence of a massive planet candidate orbiting the young active K5V star BD+20 1790
• The Mean Magnetic Field Strength of CI Tau
• Stellar activity as noise in exoplanet detection I. Methods and application to solar-like stars and activity cycles
• The HARPS search for southern extra-solar planets. XX. Planets around the active star BD-08:2823
• Long-term stellar activity variations and their effect on radial-velocity measurements
• The effects of granulation and supergranulation on Earth-mass planet detectability in the habitable zone around F6-K4 stars
• Measuring precise radial velocities and cross-correlation function line-profile variations using a Skew Normal density
• Forward modelling of Kepler-band variability due to faculae and spots
• Stellar jitter from variable gravitational redshift: implications for RV confirmation of habitable exoplanets
• A Transient Transit Signature Associated with the Young Star RIK-210
• Optical and near-infrared stellar activity characterization of the early M dwarf Gl~205 with SOPHIE and SPIRou
• Radial-velocity variations due to meridional flows in the Sun and solar-type stars: impact on exoplanet detectability
• Characterizing the atmospheres of transiting rocky planets around late type dwarfs
• Binary-induced magnetic activity? Time-series echelle spectroscopy and photometry of HD123351 = CZ CVn
• 3D magneto-hydrodynamical simulations of stellar convective noise for improved exoplanet detection. I. Case of regularly sampled radial velocity observations
• Magnitude-squared coherence: A powerful tool for disentangling Doppler planet discoveries from stellar activity
• Precise radial velocities of giant stars VIII. Testing for the presence of planets with CRIRES Infrared Radial Velocities
• Planet transit and stellar granulation detection with interferometry
• Searching for spectroscopic binaries within transition disk objects
• ELODIE metallicity-biased search for transiting Hot Jupiters V. An intermediate-period Jovian planet orbiting HD45652
• The effect of spots on the luminosity spread of the Pleiades
• KELT-22Ab: A Massive Hot Jupiter Transiting a Near Solar Twin
• Extrasolar planets and brown dwarfs around A-F type stars - VII. Theta Cygni radial velocity variations: planets or stellar phenomenon?
• The CARMENES search for exoplanets around M dwarfs Detection of a mini-Neptune around LSPM J2116+0234 and refinement of orbital parameters of a super-Earth around GJ 686 (BD+18 3421)
• RVSPY -- Radial Velocity Survey for Planets around Young Stars. Target characterization and high-cadence survey
• Readdressing the UV solar variability with SATIRE-S: non-LTE effects
• A HARPS radial velocity search for planets in the Scorpius-Centaurus association. And its combination with the HARPS and SOPHIE young nearby stars (YNS) surveys
• Solar-like oscillations and magnetic activity of the slow rotator EK Eri
• Detection and Characterization of Extrasolar Planets through Doppler Spectroscopy
• Activity time series of old stars from late F to early K. V. Effect on exoplanet detectability with high-precision astrometry
• Unsigned magnetic flux proxy from solar optical intensity spectra
• Activity time series of old stars from late F to early K VI. Exoplanet mass characterisation and detectability in radial velocity
• The barycentric motion of exoplanet host stars: tests of solar spin-orbit coupling
• Multi-Mask Least-Squares Deconvolution: Extracting RVs using tailored masks
• Simulating Radial Velocity Observations of Trappist-1 with SPIRou
• Revisiting the multi-planetary system of the nearby star HD 20794: Confirmation of a low-mass planet in the habitable zone of a nearby G-dwarf
• Accounting for stellar activity signals in radial-velocity data by using Change Point Detection techniques
• The CARMENES search for exoplanets around M dwarfs. Line-by-line sensitivity to activity in M dwarfs
• The need for a public forecast of stellar activity to optimise exoplanet radial velocity detections & transmission spectroscopy
• An Earth-sized Planet around an M5 Dwarf Star at 22 pc
• Evidence of a substellar companion around a very young T Tauri star
• A Stellar Activity F-statistic for Exoplanet Surveys (SAFE)
• Variability of Known Exoplanet Host Stars Observed by TESS
• Tracking Advanced Planetary Systems (TAPAS) with HARPS-N. V.: A Massive Jupiter orbiting the very low metallicity giant star BD+03 2562 and a possible planet around HD~103485
• The CARMENES search for exoplanets around M dwarfs. The impact of rotation and magnetic fields on the radial velocity jitter in cool stars
• HADES RV programme with HARPS-N at TNG XIV. A candidate super-Earth orbiting the M-dwarf GJ 9689 with a period close to half the stellar rotation period
• Gl 725A b: a potential super-Earth detected with SOPHIE and SPIRou in an M dwarf binary system at 3.5 pc
• The Lowell Observatory Solar Telescope: A fiber feed into the EXtreme PREcision Spectrometer
• A statistical model of stellar variability. I. FENRIR: a physics-based model of stellar activity, and its fast Gaussian process approximation
• Using Doppler Imaging to model stellar activity and search for planets around Sun-like stars
• First Doppler image and starspot-corrected orbit for $\lambda$ Andromedae: A multifaceted activity analysis
• The GAPS Programme at TNG -- XXIII. HD 164922 d: a close-in super-Earth discovered with HARPS-N in a system with a long-period Saturn mass companion
• Radial velocity precision of ESPRESSO through the analysis of the solar twin HIP 11915
• Precise radial velocities of giant stars -- XVII. Distinguishing planets from intrinsically induced radial velocity signals in evolved stars
• Searching for Low-Mass Exoplanets Amid Stellar Variability with a Fixed Effects Linear Model of Line-by-Line Shape Changes
• The CARMENES search for exoplanets around M dwarfs : Understanding the wavelength dependence of radial velocity measurements
• Yet another star in the Albireo system -- The discovery of Albireo Ad
• Studying the variability of the He triplet to understand the detection limits of evaporating exoplanet atmospheres
• Minimal Data Fidelity for Detection of Stellar Features or Companions
• A search for transits among the δ Scuti variables in Kepler
• Activity-rotation in the dM4 star Gl 729. A possible chromospheric cycle
• CARMENES input catalog of M dwarfs VI. A time-resolved Ca II H&K catalog from archival data
• Modeling the RV and BVS of active stars
• Tidal star-planet interaction and its observed impact on stellar activity in planet-hosting wide binary systems
• Revisiting BD-06 1339b: A Likely False Positive Caused by Stellar Activity
• Near-IR and optical radial velocities of the active M dwarf star Gl 388 (AD Leo) with SPIRou at CFHT and SOPHIE at OHP: A 2.23 day rotation period and no evidence for a corotating planet