The CARMENES search for exoplanets around M dwarfs. Three temperate to warm super-Earths

Abstract

We announce the discovery of two planets orbiting the M dwarfs GJ 251 ($0.360\pm 0.015$ M${}_{\odot }$) and HD 238090 ($0.578\pm 0.021$ M${}_{\odot }$) based on CARMENES radial velocity (RV) data. In addition, we independently confirm with CARMENES data the existence of Lalande 21185 b, a planet that has recently been discovered with the SOPHIE spectrograph. All three planets belong to the class of warm or temperate super-Earths and share similar properties. The orbital periods are 14.24 d, 13.67 d, and 12.95 d and the minimum masses are $4.0\pm 0.4$ $M_{\oplus }$, $6.9\pm 0.9$ $M_{\oplus }$, and $2.7\pm 0.3$ $M_{\oplus }$ for GJ 251 b, HD 238090 b, and Lalande 21185 b, respectively. Based on the orbital and stellar properties, we estimate equilibrium temperatures of $351.0\pm 1.4$ K for GJ 251 b, $469.6\pm 2.6$ K for HD 238090 b, and $370.1\pm 6.8$ K for Lalande 21185 b. For the latter we resolve the daily aliases that were present in the SOPHIE data and that hindered an unambiguous determination of the orbital period. We find no significant signals in any of our spectral activity indicators at the planetary periods. The RV observations were accompanied by contemporaneous photometric observations. We derive stellar rotation periods of $122.1\pm 2.2$ d and $96.7\pm 3.7$ d for GJ 251 and HD 238090, respectively. The RV data of all three stars exhibit significant signals at the rotational period or its first harmonic. For GJ 251 and Lalande 21185, we also find long-period signals around 600 d, and 2900 d, respectively, which we tentatively attribute to long-term magnetic cycles. We apply a Bayesian approach to carefully model the Keplerian signals simultaneously with the stellar activity using Gaussian process regression models and extensively search for additional significant planetary signals hidden behind the stellar activity.

arXiv commentAccepted for publication in A&A

References in corpus (81)

• SciPy 1.0--Fundamental Algorithms for Scientific Computing in Python
• Galactic Stellar and Substellar Initial Mass Function
• Gaia Data Release 2. Summary of the contents and survey properties
• On the variation of the Initial Mass Function
• PARSEC: stellar tracks and isochrones with the PAdova and TRieste Stellar Evolution Code
• The Transiting Exoplanet Survey Satellite
• Validation of the new Hipparcos reduction
• Binary companions of evolved stars in APOGEE DR14: Search method and catalog of ~5,000 companions
• dynesty: A Dynamic Nested Sampling Package for Estimating Bayesian Posteriors and Evidences
• A new extensive library of PHOENIX stellar atmospheres and synthetic spectra
• The generalised Lomb-Scargle periodogram. A new formalism for the floating-mean and Keplerian periodograms
• Habitable Zones Around Main-Sequence Stars: New Estimates
• Bayes in the sky: Bayesian inference and model selection in cosmology
• The WASP Project and the SuperWASP Cameras
• Rapid growth of gas-giant cores by pebble accretion
• A super-Earth transiting a nearby low-mass star
• No planet for HD 166435
• AstroImageJ: Image Processing and Photometric Extraction for Ultra-Precise Astronomical Light Curves (Expanded Edition)
• AstroImageJ: Image Processing and Photometric Extraction for Ultra-Precise Astronomical Light Curves
• Improving PARSEC models for very low mass stars
• PARSEC evolutionary tracks of massive stars up to $350M_{\odot }$ at metallicities 0.0001$\le Z\le$0.04
• The effect of gas drag on the growth of protoplanets -- Analytical expressions for the accretion of small bodies in laminar disks
• Stellar Diameters and Temperatures II. Main Sequence K & M Stars
• Northern Sky Variability Survey (NSVS): Public data release
• RadVel: The Radial Velocity Modeling Toolkit
• The Solar Neighborhood XVII: Parallax Results from the CTIOPI 0.9m Program -- Twenty New Members of the RECONS 10 Parsec Sample
• New PARSEC evolutionary tracks of massive stars at low metallicity: testing canonical stellar evolution in nearby star forming dwarf galaxies
• A ~ 7.5 Earth-Mass Planet Orbiting the Nearby Star, GJ 876
• Spectrum radial velocity analyser (SERVAL). High-precision radial velocities and two alternative spectral indicators
• The LCES HIRES/Keck Precision Radial Velocity Exoplanet Survey
• Late-type stars members of young stellar kinematic groups - I. Single stars
• Rotation and Activity in Mid-M to L Dwarfs
• Mass-Radius Relation for Rocky Planets based on PREM
• A Gaussian process framework for modelling stellar activity signals in radial velocity data
• How to Constrain Your M dwarf II: the mass-luminosity-metallicity relation from 0.075 to 0.70$M_{\odot }$
• Juliet: a versatile modelling tool for transiting and non-transiting exoplanetary systems
• Radial velocity planets de-aliased. A new, short period for Super-Earth 55 Cnc e
• Stellar Activity Masquerading as Planets in the Habitable Zone of the M dwarf Gliese 581
• The CARMENES search for exoplanets around M dwarfs: High-resolution optical and near-infrared spectroscopy of 324 survey stars
• Transit Least Squares: Optimized transit detection algorithm to search for periodic transits of small planets
• Radius and Structure models for the First Super-Earth Planet
• Dynamics of pebbles in the vicinity of a growing planetary embryo: hydro-dynamical simulations
• Inferring probabilistic stellar rotation periods using Gaussian processes
• 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
• A catalogue of rotation and activity in early-M stars
• CARMENES input catalogue of M dwarfs. I. Low-resolution spectroscopy with CAFOS
• A public HARPS radial velocity database corrected for systematic errors
• Transit Detection in the MEarth Survey of Nearby M Dwarfs: Bridging the Clean-First, Search-Later Divide
• A Kepler Study of Starspot Lifetimes with Respect to Light Curve Amplitude and Spectral Type
• The CARMENES search for exoplanets around M dwarfs. First visual-channel radial-velocity measurements and orbital parameter updates of seven M-dwarf planetary systems
• BGLS: A Bayesian formalism for the generalised Lomb-Scargle periodogram
• A candidate super-Earth planet orbiting near the snow line of Barnard's star
• CARMENES input catalogue of M dwarfs: III. Rotation and activity from high-resolution spectroscopic observations
• 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
• CARMENES input catalogue of M dwarfs II. High-resolution imaging with FastCam
• Stacked Bayesian general Lomb-Scargle periodogram: Identifying stellar activity signals
• Magnetic cycles at different ages of stars
• 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
• The New Generation Planetary Population Synthesis (NGPPS). III. Warm super-Earths and cold Jupiters: A weak occurrence correlation, but with a strong architecture-composition link
• The CARMENES search for exoplanets around M dwarfs. Radial velocities and activity indicators from cross-correlation functions with weighted binary masks
• The effect of M dwarf starspot activity on low-mass planet detection thresholds
• HADES RV Programme with HARPS-N at TNG. VII. Rotation and activity of M-Dwarfs from time-series high-resolution spectroscopy of chromospheric indicators
• The HARPS search for southern extra-solar planets XLII. A system of Earth-mass planets around the nearby M dwarf YZ Ceti
• The CARMENES search for exoplanets around M dwarfs - HD 147379b: A nearby Neptune in the temperate zone of an early-M dwarf
• 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 SOPHIE search for northern extrasolar planets. XIV. A temperate ($T_{\mathrm{eq}}\sim 300$ K) super-earth around the nearby star Gliese 411
• Exoplanet Imitators: A test of stellar activity behavior in radial velocity signals
• The CARMENES search for exoplanets around M dwarfs. Characterization of the nearby ultra-compact multiplanetary system YZ Ceti
• Robo-AO M Dwarf Multiplicity Survey: Catalog
• Inflection point in the power spectrum of stellar brightness variations. I. The model
• Gliese 49: Activity evolution and detection of a super-Earth
• Precise radial velocities of giant stars. XII. Evidence against the proposed planet Aldebaran b
• An X-ray and UV flare from the galaxy XMMSL1 J061927.1-655311
• Efficient scheduling of astronomical observations. Application to the CARMENES radial-velocity survey
• An investigation into the radial velocity variability of GJ 581 - On the significance of GJ 581g
• Inner rocky super-Earth formation: distinguishing the formation pathways in viscously heated and passive discs
• The theoretical instability strip of M dwarf stars
• Transition from spot to faculae domination -- An alternate explanation for the dearth of intermediate \textit{Kepler} rotation periods

Cited by in corpus (37)

• The CARMENES search for exoplanets around M dwarfs -- Planet occurrence rates from a subsample of 71 stars
• The 10 parsec sample in the Gaia era
• Gaia DR3 astrometric orbit determination with Markov Chain Monte Carlo and Genetic Algorithms. Systems with stellar, substellar, and planetary mass companions
• The CARMENES search for exoplanets around M dwarfs. Guaranteed time observations Data Release 1 (2016-2020)
• RV-detected planets around M dwarfs: Challenges for core accretion models
• A More Precise Mass for GJ 1214 b and the Frequency of Multi-Planet Systems Around Mid-M Dwarfs
• Detailed Chemical Abundances for a Benchmark Sample of M Dwarfs from the APOGEE Survey
• An ultra-short-period transiting super-Earth orbiting the M3 dwarf TOI-1685
• Mass and density of the transiting hot and rocky super-Earth LHS 1478 b (TOI-1640 b)
• The SPIRou Legacy Survey Rotation period of quiet M dwarfs from circular polarization in near-infrared spectral lines: I. The SPIRou APERO analysis
• The HD 260655 system: Two rocky worlds transiting a bright M dwarf at 10 pc
• The TIME Table: Rotation and Ages of Cool Exoplanet Host Stars
• The CARMENES search for exoplanets around M dwarfs, Wolf 1069 b: Earth-mass planet in the habitable zone of a nearby, very low-mass star
• TOI-1468: A system of two transiting planets, a super-Earth and a mini-Neptune, on opposite sides of the radius valley
• A transiting, temperate mini-Neptune orbiting the M dwarf TOI-1759 unveiled by TESS
• Discovery and mass measurement of the hot, transiting, Earth-sized planet GJ 3929 b
• 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
• Gaussian processes for radial velocity modeling Better rotation periods and planetary parameters with the quasi-periodic kernel and constrained priors
• $\text{Wapiti}$: a data-driven approach to correct for systematics in RV data -- Application to SPIRou data of the planet-hosting M dwarf GJ 251
• The CARMENES search for exoplanets around M dwarfs. Variability on long timescales as seen in chromospheric indicators
• The Detectability of Nightside City Lights on Exoplanets
• The Atmospheres of Rocky Exoplanets II. Influence of surface composition on the diversity of cloud condensates
• Confirmation of the Long-Period Planet Orbiting Gliese 411 and the Detection of a New Planet Candidate
• A Harsh Test of Far-Field Scrambling with the Habitable Zone Planet Finder and the Hobby Eberly Telescope
• Galactic cosmic ray propagation through M dwarf planetary systems
• Discovery of an inflated hot Jupiter around a slightly evolved star TOI-1789
• The CARMENES search for exoplanets around M dwarfs. A sub-Neptunian mass planet in the habitable zone of HN Lib
• A One-Dimensional Energy Balance Model Parameterization for the Formation of CO2 Ice on the Surfaces of Eccentric Extrasolar Planets
• GTC/CanariCam deep mid-infrared imaging survey of northern stars within 5 pc
• Dual-Backend Multibeam Position Switching Targeted SETI Observations toward Nearby Active Planet-Hosting Systems with FAST
• Discovery of a Nearby Habitable Zone Super-Earth Candidate Amenable to Direct Imaging
• Confronting compositional confusion through the characterisation of the sub-Neptune orbiting HD 77946
• SPORES-HWO. II. Companion Mass Limits and Updated Planet Properties for 120 Future Exoplanet Imaging Targets from 35 yr of Precise Doppler Monitoring
• Dynamical architecture of the HD 107148 system
• TOI-1201 b: A mini-Neptune transiting a bright and moderately young M dwarf
• How to measure tidal dissipation in long resonant chains
• CARMENES input catalog of M dwarfs VI. A time-resolved Ca II H&K catalog from archival data