Affer, L.; Damasso, M.; Micela, G.; Poretti, E.; Scandariato, G.; Maldonado, J.; Lanza, A. F.; Covino, E.; Garrido Rubio, A.; González Hernández, J. I.; Gratton, R.; Leto, G.; Maggio, A.; Perger, M.; Sozzetti, A.; Suárez Mascareño, A.; Bonomo, A. S.; Borsa, F.; Claudi, R.; Cosentino, R.; Desidera, S.; Giacobbe, P.; Molinari, E.; Pedani, M.; Pinamonti, M.; Rebolo, R.; Ribas, I.; Toledo-Padrón, B.
Bibliographical reference
Astronomy and Astrophysics, Volume 622, id.A193, 18 pp.
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2019
Journal
Citations
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Refereed citations
22
Description
Aims: The HArps-n red Dwarf Exoplanet Survey (HADES) 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 (RV) measurements in a narrow range of spectral
sub-types. Using the HARPS-N spectrograph we reach the precision needed
to detect small planets with a few earth masses. Our survey is mainly
focused on the M-dwarf population of the northern hemisphere.
Methods: As part of that program, we obtained RV measurements of Gl 686,
an M1 dwarf at d = 8.2 pc. These measurements show a dispersion much in
excess of their internal errors. 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 used a Bayesian framework to estimate the orbital parameters and the
planet minimum mass, and to properly treat the activity noise. We took
advantage of the available RV measurements for this target from other
observing campaigns. The analysis of the RV composite time series from
the HIRES, HARPS, and HARPS-N spectrographs, consisting of 198
measurements taken over 20 yr, enabled us to address the nature of
periodic signals and also to characterize stellar physical parameters
(mass, temperature, and rotation). Results: We report the
discovery of a super-Earth orbiting at a distance of 0.092 AU from the
host star Gl 686. The planet has a minimum mass of 7.1 ± 0.9
M⊕ and an orbital period of 15.532 ± 0.002 d.
The analysis of the activity indexes, of the correlated noise through a
Gaussian process framework, and of the 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 yr. The
observed periodicities around 2000 d likely point to the existence of an
activity cycle.
RV data (Table A.1) and APACHE and EXORAP photometry are only available
at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr
(ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/622/A193Based
on observations made with the Italian Telescopio Nazionale Galileo
(TNG), operated on the island of La Palma by the INAF - Fundación
Galileo Galilei at the Roche de Los Muchachos Observatory of the
Instituto de Astrofísica de Canarias (IAC); photometric
observations made with the APACHE array located at the Astronomical
Observatory of the Aosta Valley; photometric observations made with the
robotic telescope APT2 (within the EXORAP program) located at Serra La
Nave on Mt. Etna.
Related projects
ARES: High Spectral Resolution
ARES (High Spectral Resolution) is a coordinated project which attempt to join and consolidate the efforts on instrument developments at high spectral resolution within the IAC. The goal is to launch the scientific programs that the IAC carries out on the search and characterization of exoplanets, in particular Earth-like exoplanets, on the
Jonay Isai
González Hernández