HADES RV Programme with HARPS-N at TNG VI. GJ 3942 b behind dominant activity signals

Abstract

Short- to mid-term magnetic phenomena on the stellar surface of M-type stars cannot only resemble the effects of planets in radial velocity data, but also may hide them. We analyze 145 spectroscopic HARPS-N observations of GJ 3942 taken over the past five years and additional photometry to disentangle stellar activity effects from genuine Doppler signals as a result of the orbital motion of the star around the common barycenter with its planet. To achieve this, we use the common methods of pre-whitening, and treat the correlated red noise by a first-order moving average term and by Gaussian-process regression following an MCMC analysis. We identify the rotational period of the star at 16.3 days and discover a new super-Earth, GJ 3942 b, with an orbital period of 6.9 days and a minimum mass of 7.1 Me. An additional signal in the periodogram of the residuals is present but we cannot claim it to be related to a second planet with sufficient significance at this point. If confirmed, such planet candidate would have a minimum mass of 6.3 Me and a period of 10.4 days, which might indicate a 3:2 mean-motion resonance with the inner planet.

References in corpus (68)

• Validation of the new Hipparcos reduction
• The USNO-B Catalog
• Gaia Data Release 1. Summary of the astrometric, photometric, and survey properties
• The generalised Lomb-Scargle periodogram. A new formalism for the floating-mean and Keplerian periodograms
• Habitable Zones Around Main-Sequence Stars: New Estimates
• Seven temperate terrestrial planets around the nearby ultracool dwarf star TRAPPIST-1
• A terrestrial planet candidate in a temperate orbit around Proxima Centauri
• Architecture and Dynamics of Kepler's Candidate Multiple Transiting Planet Systems
• EXOFAST: A fast exoplanetary fitting suite in IDL
• The HARPS search for southern extra-solar planets XXXI. The M-dwarf sample
• Planets and Stellar Activity: Hide and Seek in the CoRoT-7 system
• Improving the Efficiency of Markov Chain Monte Carlo for Analyzing the Orbits of Extrasolar Planets
• A Gaussian process framework for modelling stellar activity signals in radial velocity data
• The HARPS-TERRA project I. Description of the algorithms, performance and new measurements on a few remarkable stars observed by HARPS
• A dynamically-packed planetary system around GJ667C with three super-Earths in its habitable zone
• The first WASP public data release
• A seven-planet resonant chain in TRAPPIST-1
• Stellar Activity Masquerading as Planets in the Habitable Zone of the M dwarf Gliese 581
• The NASA-UC-UH Eta-Earth Program: IV. A Low-mass Planet Orbiting an M Dwarf 3.6 PC from Earth
• Planetary detection limits taking into account stellar noise. I. Observational strategies to reduce stellar oscillation and granulation effects
• The HARPS search for southern extra-solar planets. X. A m sin i = 11 Mearth planet around the nearby spotted M dwarf GJ 674
• Stellar activity of planetary host star HD 189733
• Long-term magnetic activity of a sample of M-dwarf stars from the HARPS program I. Comparison of activity indices
• High-cadence spectroscopy of M-dwarfs. I. Analysis of systematic effects in HARPS-N line profile measurements on the bright binary GJ 725A+B
• A High-Precision NIR Survey for RV Variable Low-Mass Stars
• Efficient fitting of multiplanet Keplerian models to radial velocity and astrometry data
• Rotation periods of late-type dwarf stars from time-series high-resolution spectroscopy of chromospheric indicators
• A catalogue of rotation and activity in early-M stars
• CARMENES input catalogue of M dwarfs. I. Low-resolution spectroscopy with CAFOS
• The Habitable-Zone Planet Finder: A Stabilized Fiber-Fed NIR Spectrograph for the Hobby-Eberly Telescope
• Rotation, differential rotation, and gyrochronology of active Kepler stars
• The Sun as a planet-host star: Proxies from SDO images for HARPS radial-velocity variations
• The Kepler-10 planetary system revisited by HARPS-N: A hot rocky world and a solid Neptune-mass planet
• The TRENDS High-Contrast Imaging Survey. IV. The Occurrence Rate of Giant Planets around M-Dwarfs
• Determining the Mass of Kepler-78b With Nonparametric Gaussian Process Estimation
• The effect of activity on stellar temperatures and radii
• The GAPS programme with HARPS-N at TNG. I: Observations of the Rossiter-McLaughlin effect and characterisation of the transiting system Qatar-1
• SPIRou: the near-infrared spectropolarimeter/high-precision velocimeter for the Canada-France-Hawaii telescope
• The HARPS search for southern extra-solar planets. XXXVIII. Bayesian re-analysis of three systems. New super-Earths, unconfirmed signals, and magnetic cycles
• Habitable-zone super-Earth candidate in a six-planet system around the K2.5V star HD 40307
• The HARPS search for southern extra-solar planets XXXV. The interesting case of HD41248: stellar activity, no planets?
• Radial-Velocity Fitting Challenge. II. First results of the analysis of the data set
• Kepler-21b: A rocky planet around a V = 8.25 magnitude star
• Uncovering the planets and stellar activity of CoRoT-7 using only radial velocities
• Bayesian analysis of radial velocity data of GJ667C with correlated noise: evidence for only 2 planets
• Characterisation of the radial velocity signal induced by rotation in late-type dwarfs
• Do stellar magnetic cycles influence the measurement of precise radial velocities?
• The GAPS Programme with HARPS-N at TNG. VII. Putting exoplanets in the stellar context: magnetic activity and asteroseismology of $\tau$ Bootis A
• Modelling the photosphere of active stars for planet detection and characterization
• Radial Velocity Fitting Challenge. I. Simulating the data set including realistic stellar radial-velocity signals
• The Na I D resonance lines in main sequence late-type stars
• A semi-empirical stability criterion for real planetary systems
• The HADES RV Programme with HARPS-N@TNG - GJ 3998: An early M-dwarf hosting a system of Super-Earths
• Long-term radial-velocity variations of the Sun as a star: The HARPS view
• The HADES RV Programme with HARPS-N@TNG II. Data treatment and simulations
• The HADES RV Programme with HARPS-N@TNG. III. Flux-flux and activity-rotation relationships of early-M dwarfs
• Near 3:2 and 2:1 mean motion resonances formation in the systems observed by Kepler
• The GAPS Programme with HARPS-N@TNG II: No giant planets around the metal-poor star HIP 11952
• HADES RV Programme with HARPS-N at TNG: V. A super-Earth on the inner edge of the habitable zone of the nearby M-dwarf GJ 625
• Proxima Centauri reloaded: Unravelling the stellar noise in radial velocities
• The HADES RV Programme with HARPS-N@TNG IV. Time resolved analysis of the Ca ii H&K and Hα chromospheric emission of low-activity early-type M dwarfs
• The APACHE Project
• A super-Earth orbiting the nearby M-dwarf GJ 536
• Photometric transit search for planets around cool stars from the western Italian Alps: A pilot study
• An investigation into the radial velocity variability of GJ 581 - On the significance of GJ 581g
• On the radial velocity detection of additional planets in transiting, slowly rotating M-dwarf systems: the case of GJ 1132
• The Infrared Imaging Spectrograph (IRIS) for TMT: the ADC optical design
• A Consistent Orbital Stability Analysis for the GJ 581 System

Cited by in corpus (15)

• HADES RV Programme with HARPS-N at TNG. VII. Rotation and activity of M-Dwarfs from time-series high-resolution spectroscopy of chromospheric indicators
• HADES RV Programme with HARPS-N at TNG XV. Planetary occurrence rates around early-M dwarfs
• The CARMENES search for exoplanets around M dwarfs. A Neptune-mass planet traversing the habitable zone around HD 180617
• The CARMENES search for exoplanets around M dwarfs. Mapping stellar activity indicators across the M dwarf domain
• Exomoons in the habitable zones of M dwarfs
• The CARMENES search for exoplanets around M dwarfs: The warm super-Earths in twin orbits around the mid-type M dwarfs Ross 1020 (GJ 3779) and LP 819-052 (GJ 1265)
• Gliese 49: Activity evolution and detection of a super-Earth
• HADES RV program with HARPS-N at TNG. IX. A super-Earth around the M dwarf Gl686
• The HADES RV Programme with HARPS-N at TNG XI. GJ 685 b: a warm super-Earth around an active M dwarf
• Biases in retrieving planetary signals in the presence of quasi-periodic stellar activity
• Stellar masks and bisector's shape for M-type stars observed in the GAPS Programme with HARPS-N at TNG
• A super-Earth on a close-in orbit around the M1V star GJ 740. A HADES and CARMENES collaboration
• The CARMENES search for exoplanets around M dwarfs. Line-by-line sensitivity to activity in M dwarfs
• Discovery of a cold giant planet and mass measurement of a hot super-Earth in the multi-planetary system WASP-132
• 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