HADES RV program with HARPS-N at TNG. IX. A super-Earth around the M dwarf Gl686

Abstract

The HArps-n red Dwarf Exoplanet Survey is providing a major contribution to the widening of the current statistics of low-mass planets, through the in-depth analysis of precise radial velocity measurements in a narrow range of spectral sub-types. As part of that program, we obtained radial velocity measurements of Gl 686, an M1 dwarf at d = 8.2 pc. The analysis of data obtained within an intensive observing campaign demonstrates that the excess dispersion is due to a coherent signal, with a period of 15.53 d. Almost simultaneous photometric observations were carried out within the APACHE and EXORAP programs to characterize the stellar activity and to distinguish periodic variations related to activity from signals due to the presence of planetary companions, complemented also with ASAS photometric data. We took advantage of the available radial velocity measurements for this target from other observing campaigns. The analysis of the radial velocity composite time series from the HIRES, HARPS and HARPS-N spectrographs, consisting of 198 measurements taken over 20 years, enabled us to address the nature of periodic signals and also to characterize stellar physical parameters (mass, temperature, and rotation). We report the discovery of a super-Earth orbiting at a distance of 0.092 AU from the host star Gl 686. Gl 686 b has a minimum mass of 7.1 +/- 0.9 MEarth and an orbital period of 15.532 +/- 0.002 d. The analysis of the activity indexes, correlated noise through a Gaussian process framework and photometry, provides an estimate of the stellar rotation period at 37 d, and highlights the variability of the spot configuration during the long timespan covering 20 yrs. The observed periodicities around 2000 d likely point to the existence of an activity cycle.

21 pages, 17 figures, changed paper numbering from X to IX, added a co-author. arXiv admin note: text overlap with arXiv:1607.03632

References in corpus (25)

• The Gaia mission
• 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
• Detection of Thermal Emission from an Extrasolar Planet
• Planets and Stellar Activity: Hide and Seek in the CoRoT-7 system
• Radial velocity planets de-aliased. A new, short period for Super-Earth 55 Cnc e
• A new list of thorium and argon spectral lines in the visible
• 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
• Exploring The Frequency Of Close-In Jovian Planets Around M Dwarfs
• Efficient fitting of multiplanet Keplerian models to radial velocity and astrometry data
• Magnetic activity in the HARPS M-dwarf sample. The rotation-activity relationship for very low-mass stars through R'HK
• Bayesian search for low-mass planets around nearby M dwarfs. Estimates for occurrence rate based on global detectability statistics
• A nearby M star with three transiting super-Earths discovered by K2
• The HARPS search for southern extra-solar planets: XIV. Gl 176b, a super-Earth rather than a Neptune, and at a different period
• Stellar activity mimics a habitable-zone planet around Kapteyn's star
• 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 HARPS search for southern extra-solar planets XLII. A system of Earth-mass planets around the nearby M dwarf YZ Ceti
• The Equilibrium Temperature of Planets in Elliptical Orbits
• 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
• The HADES RV Programme with HARPS-N@TNG. III. Flux-flux and activity-rotation relationships of early-M dwarfs
• 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

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