First VLTI/GRAVITY Observations of HIP 65426 b: Evidence for a Low or Moderate Orbital Eccentricity
Abstract
Giant exoplanets have been directly imaged over orders of magnitude of orbital separations, prompting theoretical and observational investigations of their formation pathways. In this paper, we present new VLTI/GRAVITY astrometric data of HIP 65426 b, a cold, giant exoplanet which is a particular challenge for most formation theories at a projected separation of 92 au from its primary. Leveraging GRAVITY's astrometric precision, we present an updated eccentricity posterior that disfavors large eccentricities. The eccentricity posterior is still prior-dependent, and we extensively interpret and discuss the limits of the posterior constraints presented here. We also perform updated spectral comparisons with self-consistent forward-modeled spectra, finding a best fit ExoREM model with solar metallicity and C/O=0.6. An important caveat is that it is difficult to estimate robust errors on these values, which are subject to interpolation errors as well as potentially missing model physics. Taken together, the orbital and atmospheric constraints paint a preliminary picture of formation inconsistent with scattering after disk dispersal. Further work is needed to validate this interpretation. Analysis code used to perform this work is available at https://github.com/sblunt/hip65426.
Keywords
Cite
@article{arxiv.2310.00148,
title = {First VLTI/GRAVITY Observations of HIP 65426 b: Evidence for a Low or Moderate Orbital Eccentricity},
author = {S. Blunt and W. O. Balmer and J. J. Wang and S. Lacour and S. Petrus and G. Bourdarot and J. Kammerer and N. Pourré and E. Rickman and J. Shangguan and T. Winterhalder and R. Abuter and A. Amorim and R. Asensio-Torres and M. Benisty and J. -P. Berger and H. Beust and A. Boccaletti and A. Bohn and M. Bonnefoy and H. Bonnet and W. Brandner and F. Cantalloube and P. Caselli and B. Charnay and G. Chauvin and A. Chavez and E. Choquet and V. Christiaens and Y. Clénet and V. Coudé du Foresto and A. Cridland and R. Dembet and A. Drescher and G. Duvert and A. Eckart and F. Eisenhauer and H. Feuchtgruber and P. Garcia and R. Garcia Lopez and E. Gendron and R. Genzel and S. Gillessen and J. H. Girard and X. Haubois and G. Heißel and Th. Henning and S. Hinkley and S. Hippler and M. Horrobin and M. Houllé and Z. Hubert and L. Jocou and M. Keppler and P. Kervella and L. Kreidberg and A. -M. Lagrange and V. Lapeyrère and J. -B. Le Bouquin and P. Léna and D. Lutz and A. -L. Maire and F. Mang and G. -D. Marleau and A. Mérand and P. Mollière and J. D. Monnier and C. Mordasini and D. Mouillet and E. Nasedkin and M. Nowak and T. Ott and G. P. P. L. Otten and C. Paladini and T. Paumard and K. Perraut and G. Perrin and O. Pfuhl and L. Pueyo and J. Rameau and L. Rodet and Z. Rustamkulov and T. Shimizu and D. Sing and T. Stolker and C. Straubmeier and E. Sturm and L. J. Tacconi and E. F. van Dishoeck and A. Vigan and F. Vincent and K. Ward-Duong and F. Widmann and E. Wieprecht and E. Wiezorrek and J. Woillez and S. Yazici and A. Young},
journal= {arXiv preprint arXiv:2310.00148},
year = {2023}
}
Comments
28 pages, 14 figures. Revised and resubmitted to AJ