Discovery of a Nearby Habitable Zone Super-Earth Candidate Amenable to Direct Imaging

Abstract

We present the discovery of GJ 251 c, a candidate super-Earth orbiting in the Habitable Zone (HZ) of its M dwarf host star. Using high-precision Habitable-zone Planet Finder (HPF) and NEID RVs, in conjunction with archival RVs from the Keck I High Resolution Echelle Spectrometer (HIRES), the Calar Alto high-Resolution search for M dwarfs with Exoearths with Near-infrared and optical Echelle Spectrograph (CARMENES), and the SPectropolarimètre InfraROUge (SPIRou), we improve the measured parameters of the known planet, GJ 251 b ($P_b$ = 14.2370 days; $m\sin (i)$ = 3.85${}_{-0.33}^{+0.35}$ M${}_{\oplus }$), and we significantly constrain the minimum mass of GJ 251 c, placing it in a plausibly terrestrial regime (P${}_c$ = 53.647 $\pm$ 0.044 days; $m\sin i_c$ = 3.84 $\pm$ 0.75 M${}_{\oplus }$). Using activity mitigation techniques that leverage chromatic information content, we perform a color-dependent analysis of the system and a detailed comparison of more than 50 models that describe the nature of the planets and stellar activity in the system. Due to GJ 251's proximity to Earth (5.5 pc), next generation, thirty meter class telescopes will likely be able to image terrestrial planets in GJ 251's HZ. In fact, GJ 251 c is currently the best candidate for terrestrial, HZ planet imaging in the Northern Sky.

Accepted for publication

References in corpus (54)

• Array Programming with NumPy
• The Astropy Project: Sustaining and Growing a Community-oriented Open-source Project and the Latest Major Release (v5.0) of the Core Package
• The Transiting Exoplanet Survey Satellite
• The James Webb Space Telescope
• Estimating distances from parallaxes. V: Geometric and photogeometric distances to 1.47 billion stars in Gaia Early Data Release 3
• Direct Imaging of Multiple Planets Orbiting the Star HR 8799
• 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
• Gaia Early Data Release 3: The astrometric solution
• EXOFAST: A fast exoplanetary fitting suite in IDL
• Habitable Zones Around Main-Sequence Stars: Dependence on Planetary Mass
• 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
• Atmospheric Retrieval for Super-Earths: Uniquely Constraining the Atmospheric Composition with Transmission Spectroscopy
• Precision Stellar Characterization of FGKM Stars using an Empirical Spectral Library
• Stellar Activity Masquerading as Planets in the Habitable Zone of the M dwarf Gliese 581
• Inferring probabilistic stellar rotation periods using Gaussian processes
• Large Interferometer For Exoplanets (LIFE): I. Improved exoplanet detection yield estimates for a large mid-infrared space-interferometer mission
• SPIRou: nIR velocimetry & spectropolarimetry at the CFHT
• Atmospheric Reconnaissance of TRAPPIST-1 b with JWST/NIRISS: Evidence for Strong Stellar Contamination in the Transmission Spectra
• A Kepler Study of Starspot Lifetimes with Respect to Light Curve Amplitude and Spectral Type
• A Catalog of Kepler Habitable Zone Exoplanet Candidates
• A candidate short-period sub-Earth orbiting Proxima Centauri
• The Precision of Mass Measurements Required for Robust Atmospheric Characterization of Transiting Exoplanets
• Stellar activity mimics a habitable-zone planet around Kapteyn's star
• Line-by-line velocity measurements, an outlier-resistant method for precision velocimetry
• Kepler-21b: A rocky planet around a V = 8.25 magnitude star
• Direct detection of exoplanets in the 3 -- 10 micron range with E-ELT/METIS
• Doppler Imaging of Exoplanets and Brown Dwarfs
• The CARMENES search for exoplanets around M dwarfs. Guaranteed time observations Data Release 1 (2016-2020)
• A temperate exo-Earth around a quiet M dwarf at 3.4 parsecs
• APERO: A PipelinE to Reduce Observations -- Demonstration with SPIRou
• A Versatile Technique to Enable sub-milli-Kelvin Instrument Stability for Precise Radial Velocity Measurements: Tests with the Habitable-zone Planet Finder
• The Warm Neptune GJ 3470b has a Polar Orbit
• Diving Beneath the Sea of Stellar Activity: Chromatic Radial Velocities of the Young AU Mic Planetary System
• A sub-Neptune sized planet transiting the M2.5-dwarf G 9-40: Validation with the Habitable-zone Planet Finder
• From super-Earths to sub-Neptunes: Observational constraints and connections to theoretical models
• Spectrum-driven Planetary Deglaciation Due to Increases in Stellar Luminosity
• LHS 1140 b is a potentially habitable water world
• Overfitting Affects the Reliability of Radial Velocity Mass Estimates of the V1298 Tau Planets
• The CARMENES search for exoplanets around M dwarfs. Three temperate to warm super-Earths
• Bioverse: A Comprehensive Assessment of the Capabilities of Extremely Large Telescopes to Probe Earth-like O${}_2$ Levels in Nearby Transiting Habitable Zone Exoplanets
• Setting the stage for the search for life with the Habitable Worlds Observatory: Properties of 164 promising planet survey targets
• 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: Two Saturn-mass planets orbiting active stars
• The Lick-Carnegie Exoplanet Survey: Gliese 687b: A Neptune-Mass Planet Orbiting a Nearby Red Dwarf
• A sub-Earth-mass planet orbiting Barnard's star
• $\text{Wapiti}$: a data-driven approach to correct for systematics in RV data -- Application to SPIRou data of the planet-hosting M dwarf GJ 251
• Rotational modulation of spectroscopic Zeeman signatures in low-mass stars
• Towards Extremely Precise Radial Velocities: I. Simulated Solar Spectra for Testing Exoplanet Detection Algorithms
• The pale blue dot: using the Planetary Spectrum Generator to simulate signals from hyper realistic exo-Earths
• The CARMENES search for exoplanets around M dwarfs. Revisiting the GJ 581 multi-planetary system with new Doppler measurements from CARMENES, HARPS, and HIRES
• The TESS-Keck Survey. XIII. An Eccentric Hot Neptune with a Similar-Mass Outer Companion around TOI-1272
• Gl 725A b: a potential super-Earth detected with SOPHIE and SPIRou in an M dwarf binary system at 3.5 pc