Nagel, E.; Czesla, S.; Schmitt, J. H. M. M.; Dreizler, S.; Anglada-Escudé, G.; Rodríguez, E.; Ribas, I.; Reiners, A.; Quirrenbach, A.; Amado, P. J.; Caballero, J. A.; Aceituno, J.; Béjar, V. J. S.; Cortés-Contreras, M.; González-Cuesta, L.; Guenther, E. W.; Henning, T.; Jeffers, S. V.; Kaminski, A.; Kürster, M.; Lafarga, M.; López-González, M. J.; Montes, D.; Morales, J. C.; Passegger, V. M.; Rodríguez-López, C.; Schweitzer, A.; Zechmeister, M.
Bibliographical reference
Astronomy and Astrophysics, Volume 622, id.A153, 13 pp.
Description
We report the detection of a Neptune-mass exoplanet around the M4.0
dwarf GJ 4276 (G 232-070) based on radial velocity (RV) observations
obtained with the CARMENES spectrograph. The RV variations of GJ 4276
are best explained by the presence of a planetary companion that has a
minimum mass of mb sin i ≈ 16 M⊕ on a
Pb = 13.35 day orbit. The analysis of the activity indicators
and spectral diagnostics exclude stellar induced RV perturbations and
prove the planetary interpretation of the RV signal. We show that a
circular single-planet solution can be excluded by means of a likelihood
ratio test. Instead, we find that the RV variations can be explained
either by an eccentric orbit or interpreted as a pair of planets on
circular orbits near a period ratio of 2:1. Although the eccentric
single-planet solution is slightly preferred, our statistical analysis
indicates that none of these two scenarios can be rejected with high
confidence using the RV time series obtained so far. Based on the
eccentric interpretation, we find that GJ 4276 b is the most eccentric
(eb = 0.37) exoplanet around an M dwarf with such a short
orbital period known today.
Photometric measurements and Table C.1 are 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/A153
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