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

Abstract

Context: A challenge with radial-velocity (RV) data is disentangling the origin of signals either due to a planetary companion or to stellar activity. In fact, the existence of a planetary companion has been proposed, as well as contested, around the relatively bright, nearby M3.0V star AD Leo at the same period as the stellar rotation of 2.23d. Aims: We further investigate the nature of this signal. We introduce new CARMENES optical and near-IR RV data and an analysis in combination with archival data taken by HIRES and HARPS, along with more recent data from HARPS-N, GIANO-B, and HPF. Also, we address the confusion concerning the binarity of AD Leo. Methods: We consider possible correlations between the RVs and various stellar activity indicators accessible with CARMENES. We applied models within a Bayesian framework to determine whether a Keplerian model, a red-noise quasi-periodic model using a Gaussian process, or a mixed model would explain the observed data best. We also exclusively focus on spectral lines potentially associated with stellar activity. Results: The CARMENES RV data agree with the previously reported periodicity of 2.23d, correlate with some activity indicators, and exhibit chromaticity. However, when considering the entire RV data set, we find that a mixed model composed of a stable and a variable component performs best. Moreover, when recomputing the RVs using only spectral lines insensitive to activity, there appears to be some residual power at the period of interest. We therefore conclude that it is not possible to determinedly prove that there is no planet orbiting in synchronization with the stellar rotation given our data, current tools, machinery, and knowledge of how stellar activity affects RVs. We do rule out planets more massive than 27M_E (=0.084M_J). We also exclude any binary companion around AD Leo with Msini > 3-6M_J on orbital periods <14yr.

arXiv comment27 pages, 11 figures

References in corpus (113)

• Validation of the new Hipparcos reduction
• dynesty: A Dynamic Nested Sampling Package for Estimating Bayesian Posteriors and Evidences
• Gaia Data Release 2: The astrometric solution
• The generalised Lomb-Scargle periodogram. A new formalism for the floating-mean and Keplerian periodograms
• A terrestrial planet candidate in a temperate orbit around Proxima Centauri
• Bayes in the sky: Bayesian inference and model selection in cosmology
• Fast and scalable Gaussian process modeling with applications to astronomical time series
• How to Constrain Your M Dwarf: measuring effective temperature, bolometric luminosity, mass, and radius
• The HARPS search for southern extra-solar planets XXXI. The M-dwarf sample
• ESPRESSO@VLT -- On-sky performance and first results
• RadVel: The Radial Velocity Modeling Toolkit
• 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
• The LCES HIRES/Keck Precision Radial Velocity Exoplanet Survey
• Large-scale magnetic topologies of mid-M dwarfs
• Late-type stars members of young stellar kinematic groups - I. Single stars
• A Gaussian process framework for modelling stellar activity signals in radial velocity data
• Metallicity and Temperature Indicators in M dwarf K band Spectra: Testing New & Updated Calibrations With Observations of 133 Solar Neighborhood M dwarfs
• Juliet: a versatile modelling tool for transiting and non-transiting exoplanetary systems
• Gaia Early Data Release 3: The Gaia Catalogue of Nearby Stars
• Radial velocity planets de-aliased. A new, short period for Super-Earth 55 Cnc e
• Trumpeting M Dwarfs with CONCH-SHELL: a Catalog of Nearby Cool Host-Stars for Habitable ExopLanets and Life
• A Spectroscopic Catalog of the Brightest (J<9) M Dwarfs in the Northern Sky
• SOAP 2.0: A tool to estimate the photometric and radial velocity variations induced by stellar spots and plages
• 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
• Stellar Rotation Periods of the Kepler Objects of Interest: A Dearth of Close-in Planets around Fast Rotators
• Long-term magnetic activity of a sample of M-dwarf stars from the HARPS program I. Comparison of activity indices
• Detecting Planets Around Very Low Mass Stars with the Radial Velocity Method
• 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
• Identifying the Young Low-mass Stars within 25 pc. I. Spectroscopic Observations
• 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
• Magnetic activity in the HARPS M-dwarf sample. The rotation-activity relationship for very low-mass stars through R'HK
• Effects of M dwarf magnetic fields on potentially habitable planets
• Rotation Periods, Variability Properties and Ages for Kepler Exoplanet Candidate Host Stars
• A public HARPS radial velocity database corrected for systematic errors
• Magnetism, rotation, and nonthermal emission in cool stars -- Average magnetic field measurements in 292 M dwarfs
• SPIRou: nIR velocimetry & spectropolarimetry at the CFHT
• CARMENES input catalogue of M dwarfs V. Luminosities, colours, and spectral energy distributions
• A hot Jupiter orbiting a 2-Myr-old solar-mass T Tauri star
• BGLS: A Bayesian formalism for the generalised Lomb-Scargle periodogram
• Stellar coronal magnetic fields and star-planet interaction
• CARMENES input catalogue of M dwarfs: III. Rotation and activity from high-resolution spectroscopic observations
• A candidate short-period sub-Earth orbiting Proxima Centauri
• Accounting for velocity jitter in planet search surveys
• Ultra-Wideband Detection of 22 Coherent Radio Bursts on M Dwarfs
• Revisiting Proxima with ESPRESSO
• UV habitable zones around M stars
• Correcting HIRES radial velocities for small systematic errors
• Stellar activity mimics a habitable-zone planet around Kapteyn's star
• The CARMENES search for exoplanets around M dwarfs. Activity indicators at visible and near-infrared wavelengths
• The CARMENES search for exoplanets around M dwarfs. Stellar atmospheric parameters of target stars with SteParSyn
• Measuring precise radial velocities on individual spectral lines : II. Dependance of stellar activity signal on line depth
• A high-resolution spectroscopic survey of late-type stars: chromospheric activity, rotation, kinematics, and age
• CARMENES input catalogue of M dwarfs II. High-resolution imaging with FastCam
• Warm terrestrial planet with half the mass of Venus transiting a nearby star
• The Solar Neighborhood XXX: Fomalhaut C
• Stacked Bayesian general Lomb-Scargle periodogram: Identifying stellar activity signals
• NGTS-1b: A hot Jupiter transiting an M-dwarf
• pyaneti II: A multidimensional Gaussian process approach to analysing spectroscopic time-series
• The Moving Group Targets of the SEEDS High-Contrast Imaging Survey of Exoplanets and Disks: Results and Observations from the First Three Years
• 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
• Radial velocity signatures of Zeeman broadening
• The CARMENES search for exoplanets around M dwarfs: A low-mass planet in the temperate zone of the nearby K2-18
• The CARMENES search for exoplanets around M dwarfs. Radial velocities and activity indicators from cross-correlation functions with weighted binary masks
• 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
• A Direct Imaging Survey of Spitzer detected debris disks: Occurrence of giant planets in dusty systems
• Precision radial velocities of 15 M5 - M9 dwarfs
• Star-planet magnetic interaction and activity in late-type stars with close-in planets
• The CARMENES search for exoplanets around M dwarfs: Radial-velocity variations of active stars in visual-channel spectra
• The Impact of Stellar Rotation on the Detectability of Habitable Planets Around M Dwarfs
• Why is there a Dearth of Close-In Planets around Fast-Rotating stars?
• Monitoring the radio emission of Proxima Centauri
• Ultra-high-time Resolution Observations of Radio Bursts on AD Leonis
• Optical and X-ray observations of stellar flares on an active M dwarf AD Leonis with Seimei Telescope, SCAT, NICER and OISTER
• Microwave plasma emission of a flare on AD Leo
• Discovery of 9 New Companions to Nearby Young M Stars with the Altair AO System
• MOST Observations of the Flare Star AD Leo
• Starspot-induced optical and infrared radial velocity variability in T Tauri star Hubble 4
• Catalog for the ESPRESSO blind radial velocity exoplanet survey
• 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
• The Ca II infrared triplet's performance as an activity indicator compared to Ca II H and K
• New Methods for Finding Activity-Sensitive Spectral Lines: Combined Visual Identification and an Automated Pipeline Find a Set of 40 Activity Indicators
• High-resolution spectroscopy of flares and CMES on AD Leo*
• Analysis and modeling of high temporal resolution spectroscopic observations of flares on AD Leo
• 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
• Long-lived, long-period radial velocity variations in Aldebaran: A planetary companion and stellar activity
• 10 Years of Stellar Activity for GJ 1243
• A detailed analysis of the Gl 486 planetary system
• The Implications of M Dwarf Flares on the Detection and Characterization of Exoplanets at Infrared Wavelengths
• Mapping stellar surfaces II: An interpretable Gaussian process model for light curves
• The CARMENES search for exoplanets around M dwarfs. Mapping stellar activity indicators across the M dwarf domain
• Proxima Centauri as a Benchmark for Stellar Activity Indicators in the Near Infrared
• 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
• The CARMENES search for exoplanets around M dwarfs. Characterization of the nearby ultra-compact multiplanetary system YZ Ceti
• The EUVE point of view of AD Leo
• A HARPS RV search for planets around young nearby stars
• The CARMENES search for exoplanets around M dwarfs: Benchmarking the impact of activity in high-precision radial velocity measurements
• Auto-correlation functions of astrophysical processes, and their relation to Gaussian processes; Application to radial velocities of different starspot configurations
• Auroral Radio Emission from Ultracool Dwarfs: a Jovian Model
• AD Leonis: Radial velocity signal of stellar rotation or spin-orbit resonance?
• The CARMENES search for exoplanets around M dwarfs: Two Saturn-mass planets orbiting active stars
• TOI-519 b: a short-period substellar object around an M dwarf validated using multicolour photometry and phase curve analysis
• EUV-driven ionospheres and electron transport on extrasolar giant planets orbiting active stars
• The CARMENES search for exoplanets around M dwarfs. Two terrestrial planets orbiting G 264-012 and one terrestrial planet orbiting Gl 393
• The spectral impact of magnetic activity on disk-integrated HARPS-N solar observations: exploring new activity indicators
• Periodic Halpha variations in GL 581: Further evidence for an activity origin to GL 581d
• Activity and telluric contamination in HARPS observations of Alpha Centauri B
• The CARMENES search for exoplanets around M dwarfs. Diagnostic capabilities of strong K I lines for photosphere and chromosphere

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• Connection between planetary He I $\lambda$10830 Å absorption and extreme-ultraviolet emission of planet-host stars
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• Revisiting Radial Velocity Measurements of the K2-18 System with the Line-by-Line Framework
• Flares, Rotation, Activity Cycles and a Magnetic Star-Planet Interaction Hypothesis for the Far Ultraviolet Emission of GJ 436
• Planetary companions orbiting the M dwarfs GJ 724 and GJ 3988. A CARMENES and IRD collaboration
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• The JWST Rocky Worlds DDT Program reveals GJ 3929b to likely be a bare rock
• Radii, masses, and transit-timing variations of the three-planet system orbiting the naked-eye star TOI-396
• The CARMENES search for exoplanets around M dwarfs. The impact of rotation and magnetic fields on the radial velocity jitter in cool stars
• Starspots as the origin of ultrafast drifting radio bursts from an active M dwarf
• Multibeam SETI Observations toward Nearby M dwarfs with FAST
• The CARMENES search for exoplanets around M dwarfs : Understanding the wavelength dependence of radial velocity measurements
• Assessing the Climate and Habitability of Tidally Locked Rocky Exoplanets
• 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