The CARMENES search for exoplanets around M dwarfs. Two temperate Earth-mass planet candidates around Teegarden's Star

Abstract

Context. Teegarden's Star is the brightest and one of the nearest ultra-cool dwarfs in the solar neighbourhood. For its late spectral type (M7.0V), the star shows relatively little activity and is a prime target for near-infrared radial velocity surveys such as CARMENES. Aims. As part of the CARMENES search for exoplanets around M dwarfs, we obtained more than 200 radial-velocity measurements of Teegarden's Star and analysed them for planetary signals. Methods. We find periodic variability in the radial velocities of Teegarden's Star. We also studied photometric measurements to rule out stellar brightness variations mimicking planetary signals. Results. We find evidence for two planet candidates, each with $1.1M_{\oplus }$ minimum mass, orbiting at periods of 4.91 and 11.4 d, respectively. No evidence for planetary transits could be found in archival and follow-up photometry. Small photometric variability is suggestive of slow rotation and old age. Conclusions. The two planets are among the lowest-mass planets discovered so far, and they are the first Earth-mass planets around an ultra-cool dwarf for which the masses have been determined using radial velocities.

arXiv commentA&A 627, A49. 26 pages, 17 figures, 6 tables. Press release available at http://www.astro.physik.uni-goettingen.de/~zechmeister/teegarden/teegarden.html. v2: two authors and one reference added

References in corpus (47)

• emcee: The MCMC Hammer
• Gaia Data Release 2. Summary of the contents and survey properties
• The Transiting Exoplanet Survey Satellite
• The SIMBAD astronomical database
• 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
• Seven temperate terrestrial planets around the nearby ultracool dwarf star TRAPPIST-1
• A terrestrial planet candidate in a temperate orbit around Proxima Centauri
• A box-fitting algorithm in the search for periodic transits
• The stellar activity-rotation relationship and the evolution of stellar dynamos
• Ages for illustrative field stars using gyrochronology: viability, limitations and errors
• 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
• Habitable Zones Around Main-Sequence Stars: Dependence on Planetary Mass
• Temperate Earth-sized planets transiting a nearby ultracool dwarf star
• Constraining the Age-Activity Relation for Cool Stars: The SDSS DR5 Low-Mass Star Spectroscopic Sample
• Spectrum radial velocity analyser (SERVAL). High-precision radial velocities and two alternative spectral indicators
• Mass-Radius Relation for Rocky Planets based on PREM
• Metallicity and Temperature Indicators in M dwarf K band Spectra: Testing New & Updated Calibrations With Observations of 133 Solar Neighborhood M dwarfs
• The H$\alpha$ emission of nearby M dwarfs and its relation to stellar rotation
• The rotation and Galactic kinematics of mid M dwarfs in the Solar Neighborhood
• The CARMENES search for exoplanets around M dwarfs: High-resolution optical and near-infrared spectroscopy of 324 survey stars
• Detecting Planets Around Very Low Mass Stars with the Radial Velocity Method
• Generalized investigation of the rotation-activity relation: Favouring rotation period instead of Rossby number
• The CARMENES search for exoplanets around M dwarfs: Different roads to radii and masses of the target stars
• A Volume-limited Sample of 63 M7-M9.5 Dwarfs II. Activity, magnetism, and the fade of the rotation-dominated dynamo
• CARMENES input catalogue of M dwarfs. I. Low-resolution spectroscopy with CAFOS
• Transit Detection in the MEarth Survey of Nearby M Dwarfs: Bridging the Clean-First, Search-Later Divide
• An Activity-Rotation Relationship and Kinematic Analysis of Nearby Mid-to-Late-type M Dwarfs
• The CARMENES search for exoplanets around M dwarfs. First visual-channel radial-velocity measurements and orbital parameter updates of seven M-dwarf planetary systems
• Systemic: A Testbed For Characterizing the Detection of Extrasolar Planets. I. The Systemic Console Package
• The Solar Neighborhood XXXII. The Hydrogen Burning Limit
• Zodiacal Exoplanets in Time (ZEIT) IV: seven transiting planets in the Praesepe cluster
• Flat-relative optimal extraction. A quick and efficient algorithm for stabilised spectrographs
• CARMENES input catalogue of M dwarfs: III. Rotation and activity from high-resolution spectroscopic observations
• The period ratio distribution of Kepler's candidate multiplanet systems
• Correcting HIRES radial velocities for small systematic errors
• The CARMENES search for exoplanets around M dwarfs - Photospheric parameters of target stars from high-resolution spectroscopy
• New planetary and EB candidates from Campaigns 1-6 of the K2 mission
• Calibrating echelle spectrographs with Fabry-Perot etalons
• Discovery of a New Nearby Star
• Trigonometric Parallaxes and Proper Motions of 134 Southern Late M, L, and T Dwarfs from the Carnegie Astrometric Planet Search Program
• SPIRou: a nIR spectropolarimeter / high-precision velocimeter for the CFHT
• Testing Models of Stellar Structure and Evolution I. Comparison with Detached Eclipsing Binaries
• A probable close brown dwarf companion to GJ 1046 (M2.5V)
• Transit Visibility Zones of the Solar System Planets
• Detecting Planets around Very Cool Dwarfs at Near Infrared Wavelengths with the Radial Velocity Technique

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• Pursuing Truth: Improving Retrievals on Mid-Infrared Exo-Earth Spectra with Physically Motivated Water Abundance Profiles and Cloud Models
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• The CARMENES search for exoplanets around M dwarfs. Occurrence rates of Earth-like planets around very low-mass stars
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• ExoplANNET: A deep learning algorithm to detect and identify planetary signals in radial velocity data
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• Wave optics of the solar gravity lens
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