Astrometric detection of a Neptune-mass candidate planet in the nearest M-dwarf binary system GJ65 with VLTI/GRAVITY
Abstract
The detection of low-mass planets orbiting the nearest stars is a central stake of exoplanetary science, as they can be directly characterized much more easily than their distant counterparts. Here, we present the results of our long-term astrometric observations of the nearest binary M-dwarf Gliese 65 AB (GJ65), located at a distance of only 2.67 pc. We monitored the relative astrometry of the two components from 2016 to 2023 with the VLTI/GRAVITY interferometric instrument. We derived highly accurate orbital parameters for the stellar system, along with the dynamical masses of the two red dwarfs. The GRAVITY measurements exhibit a mean accuracy per epoch of 50-60 microarcseconds in 1.5h of observing time using the 1.8m Auxiliary Telescopes. The residuals of the two-body orbital fit enable us to search for the presence of companions orbiting one of the two stars (S-type orbit) through the reflex motion they imprint on the differential A-B astrometry. We detected a Neptune-mass candidate companion with an orbital period of p = 156 +/- 1 d and a mass of m = 36 +/- 7 Mearth. The best-fit orbit is within the dynamical stability region of the stellar pair. It has a low eccentricity, e = 0.1 - 0.3, and the planetary orbit plane has a moderate-to-high inclination of i > 30{\deg} with respect to the stellar pair, with further observations required to confirm these values. These observations demonstrate the capability of interferometric astrometry to reach microarcsecond accuracy in the narrow-angle regime for planet detection by reflex motion from the ground. This capability offers new perspectives and potential synergies with Gaia in the pursuit of low-mass exoplanets in the solar neighborhood.
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Cite
@article{arxiv.2404.08746,
title = {Astrometric detection of a Neptune-mass candidate planet in the nearest M-dwarf binary system GJ65 with VLTI/GRAVITY},
author = {GRAVITY Collaboration and R. Abuter and A. Amorim and M. Benisty and J-P. Berger and H. Bonnet and G. Bourdarot and P. Bourget and W. Brandner and Y. Clénet and R. Davies and F. Delplancke-Ströbele and R. Dembet and A. Drescher and A. Eckart and F. Eisenhauer and H. Feuchtgruber and G. Finger and N. M. Förster-Schreiber and P. Garcia and R. Garcia-Lopez and F. Gao and E. Gendron and R. Genzel and S. Gillessen and M. Hartl and X. Haubois and F. Haussmann and T. Henning and S. Hippler and M. Horrobin and L. Jochum and L. Jocou and A. Kaufer and P. Kervella and S. Lacour and V. Lapeyrère and J. B. Le Bouquin and C. Ledoux and P. Léna and D. Lutz and F. Mang and A. Mérand and N. More and M. Nowak and T. Ott and T. Paumard and K. Perraut and G. Perrin and O. Pfuhl and S. Rabien and D. C. Ribeiro and M. Sadun Bordoni and J. Shangguan and T. Shimizu and J. Stadler and O. Straub and C. Straubmeier and E. Sturm and L. J. Tacconi and K. R. W Tristram and F. Vincent and S. von Fellenberg and F. Widmann and E. Wieprecht and J. Woillez and S. Yazici and G. Zins},
journal= {arXiv preprint arXiv:2404.08746},
year = {2024}
}
Comments
Corresponding authors: G.Bourdarot, P.Kervella, O.Pfuhl. Accepted in A&A Letters