A quarter century of spectroscopic monitoring of the nearby M dwarf Gl 514. A super-Earth on an eccentric orbit moving in and out of the habitable zone

Abstract

We investigated the presence of planetary companions around the nearby (7.6 pc) and bright ($V=9$ mag) early-type M dwarf Gl 514, analysing 540 radial velocities collected over nearly 25 years with the HIRES, HARPS, and CARMENES spectrographs. The data are affected by time-correlated signals at the level of 2-3 ms${}^{-1}$ due to stellar activity, that we filtered out testing three different models based on Gaussian process regression. As a sanity cross-check, we repeated the analyses using HARPS radial velocities extracted with three different algorithms. We used HIRES radial velocities and Hipparcos-Gaia astrometry to put constraints on the presence of long-period companions, and we analysed TESS photometric data. We found strong evidence that Gl 514 hosts a super-Earth on a likely eccentric orbit, residing in the conservative habitable zone for nearly $34\%$ of its orbital period. The planet Gl 514 b has minimum mass $m_b\sin i_b=5.2\pm 0.9$ $M_{\mathrm{Earth}}$, orbital period $P_b=140.43\pm 0.41$ days, and eccentricity $e_b=0.45_{-0.14}^{+0.15}$. No evidence for transits is found in the TESS light curve. There is no evidence for a longer period companion in the radial velocities and, based on astrometry, we can rule out a $\sim 0.2$ $M_{\mathrm{Jup}}$ planet at a distance of $\sim 3-10$ au, and massive giant planets/brown dwarfs out to several tens of au. We discuss the possible presence of a second low-mass companion at a shorter distance from the host than Gl 514 b. Gl 514 b represents an interesting science case to study the habitability of planets on eccentric orbits. We advocate for additional spectroscopic follow-up to get more accurate and precise planetary parameters. Further follow-up is also needed to investigate sub \ms and shorter period signals.

34 pages, accepted for publication in Astronomy & Astrophysics

References in corpus (50)

• The Gaia mission
• Seven temperate terrestrial planets around the nearby ultracool dwarf star TRAPPIST-1
• A terrestrial planet candidate in a temperate orbit around Proxima Centauri
• Gaia Early Data Release 3: The astrometric solution
• Habitable Zones Around Main-Sequence Stars: Dependence on Planetary Mass
• ESPRESSO@VLT -- On-sky performance and first results
• 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
• An Earth-sized Planet in the Habitable Zone of a Cool Star
• The Hipparcos-Gaia Catalog of Accelerations: Gaia EDR3 Edition
• Stellar and substellar companions from Gaia EDR3 -- Proper motion anomaly and resolved common proper motion pairs
• The CARMENES search for exoplanets around M dwarfs: Different roads to radii and masses of the target stars
• Magnetic activity in the HARPS M-dwarf sample. The rotation-activity relationship for very low-mass stars through R'HK
• A public HARPS radial velocity database corrected for systematic errors
• A nearby M star with three transiting super-Earths discovered by K2
• The CARMENES search for exoplanets around M dwarfs -- Planet occurrence rates from a subsample of 71 stars
• Coherent radio emission from a quiescent red dwarf indicative of star-planet interaction
• Validation of Twelve Small Kepler Transiting Planets in the Habitable Zone
• A candidate short-period sub-Earth orbiting Proxima Centauri
• Revisiting Proxima with ESPRESSO
• Occurrence Rates of Planets Orbiting M Stars: Applying ABC to Kepler DR25, Gaia DR2, and 2MASS Data
• Characterization of the K2-18 multi-planetary system with HARPS: A habitable zone super-Earth and discovery of a second, warm super-Earth on a non-coplanar orbit
• Magnetic fields in M dwarfs from the CARMENES survey
• A temperate exo-Earth around a quiet M dwarf at 3.4 parsecs
• Stellar parameters of early M dwarfs from ratios of spectral features at optical wavelengths
• The HARPS search for southern extra-solar planets XXXV. Planetary systems and stellar activity of the M dwarfs GJ 3293, GJ 3341, and GJ 3543
• The population of M dwarfs observed at low radio frequencies
• Radial Velocity Data Analysis with Compressed Sensing Techniques
• A PSF-based Approach to TESS High quality data Of Stellar clusters (PATHOS) -- I. Search for exoplanets and variable stars in the field of 47 Tuc
• Monitoring the radio emission of Proxima Centauri
• The Equilibrium Temperature of Planets in Elliptical Orbits
• A PSF-based Approach to TESS High quality data Of Stellar clusters (PATHOS) -- II. Search for exoplanets in open clusters of the southern ecliptic hemisphere and their frequency
• Bias and robustness of eccentricity estimates from radial velocity data
• The HADES RV Programme with HARPS-N@TNG - GJ 3998: An early M-dwarf hosting a system of Super-Earths
• The HADES RV Programme with HARPS-N@TNG II. Data treatment and simulations
• HADES RV Programme with HARPS-N at TNG XV. Planetary occurrence rates around early-M dwarfs
• Constraints on the mass and atmospheric composition and evolution of the low-density young planet DS Tuc A b
• Variable stars in two open clusters within the Kepler 2-Campaign-0 field: M 35 and NGC 2158
• The CARMENES search for exoplanets around M dwarfs. Period search in H$\alpha$, Na I D, and Ca II IRT lines
• The Impact of Stellar Surface Magnetoconvection and Oscillations on the Detection of Temperate, Earth-Mass Planets Around Sun-Like Stars
• A PSF-based Approach to TESS High quality data Of Stellar clusters (PATHOS) -- III. Exploring the properties of young associations through their variables, dippers, and candidate exoplanets
• Search for Nearby Earth Analogs. II. detection of five new planets, eight planet candidates, and confirmation of three planets around nine nearby M dwarfs
• Auto-correlation functions of astrophysical processes, and their relation to Gaussian processes; Application to radial velocities of different starspot configurations
• Disentangling 2:1 resonant radial velocity orbits from eccentric ones and a case study for HD 27894
• Testing whether a signal is strictly periodic. Application to disentangling planets and stellar activity in radial velocities
• Truly eccentric. II. When can two circular planets mimic a single eccentric orbit?
• Three planets around HD 27894. A close-in pair with a 2:1 period ratio and an eccentric Jovian planet at 5.4 AU
• HADES RV program with HARPS-N at TNG. IX. A super-Earth around the M dwarf Gl686
• Which Radial Velocity Exoplanets Have Undetected Outer Companions?
• Detailed stellar activity analysis and modelling of GJ 832: Reassessment of the putative habitable zone planet GJ 832c

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• The CARMENES search for exoplanets around M dwarfs. Guaranteed time observations Data Release 1 (2016-2020)
• Two temperate Earth-mass planets orbiting the nearby star GJ1002
• 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
• Planetary companions orbiting the M dwarfs GJ 724 and GJ 3988. A CARMENES and IRD collaboration
• Constraints to the semimajor axis of outer particles with nodal librations by general relativity effects
• Exploring Climate with Obliquity in a Variable-eccentricity Earth-like World
• Earth-like planet predictor: A machine learning approach