First VLTI/GRAVITY Observations of HIP 65426 b: Evidence for a Low or Moderate Orbital Eccentricity

DOI
Publisher DOI
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 on GitHub: https://github.com/sblunt/hip65426.
Date Issued
2023
Publication Type
Article
Subject(s)
Language(s)
en
Author(s)
Blunt, Sarah
Balmer, W. O.
Wang, J. J.
Lacour, S.
Petrus, S.
Bourdarot, G.
Kammerer, J.
Pourré, N.
Rickman, E.
Shangguan, J.
Winterhalder, T.
Abuter, R.
Amorim, A.
Asensio-Torres, R.
Benisty, M.
Berger, J.-P.
Beust, H.
Boccaletti, A.
Bohn, A.
Bonnefoy, M.
Bonnet, H.
Brandner, W.
Cantalloube, F.
Caselli, P.
Charnay, B.
Chauvin, G.
Chavez, A.
Choquet, E.
Christiaens, V.
Clénet, Y.
du Foresto, V. Coudé
Cridland, A.
Dembet, R.
Drescher, A.
Duvert, G.
Eckart, A.
Eisenhauer, F.
Feuchtgruber, H.
Garcia, P.
Garcia Lopez, R.
Gendron, E.
Genzel, R.
Gillessen, S.
Girard, J. H.
Haubois, X.
Heißel, G.
Henning, Th.
Hinkley, S.
Hippler, S.
Horrobin, M.
Houllé, M.
Hubert, Z.
Jocou, L.
Keppler, M.
Kervella, P.
Kreidberg, L.
Lagrange, A.-M.
Lapeyrère, V.
Le Bouquin, J.-B.
Léna, P.
Lutz, D.
Maire, A.-L.
Mang, F.
Marleau, G.-D.
Mérand, A.
Mollière, P.
Monnier, J. D.
Mouillet, D.
Nasedkin, E.
Nowak, M.
Ott, T.
Otten, G. P. P. L.
Paladini, C.
Paumard, T.
Perraut, K.
Perrin, G.
Pfuhl, O.
Pueyo, L.
Rameau, J.
Rodet, L.
Rustamkulov, Z.
Shimizu, T.
Sing, D.
Stolker, T.
Straubmeier, C.
Sturm, E.
Tacconi, L. J.
van Dishoeck, E. F.
Vigan, A.
Vincent, F.
Ward-Duong, K.
Widmann, F.
Wieprecht, E.
Wiezorrek, E.
Woillez, J.
Yazici, S.
Young, A.
Additional Credits
Journal
The astronomical journal
Publisher
American Astronomical Society
ISSN
0004-6256
Access(Rights)
open.access
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