Author ORCID Identifier
Kimberly Ward-Duong: 0000-0002-4479-8291
Document Type
Article
Publication Date
12-1-2023
Publication Title
Astronomical Journal
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.
Volume
6
Issue
257
DOI
10.3847/1538-3881/ad06b7
ISSN
00046256
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 International License.
Rights
© 2023 The Authors
Recommended Citation
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.; al, et; and Ward-Duong, Kimberly, "First VLTI/GRAVITY Observations of HIP 65426 b: Evidence for a Low or Moderate Orbital Eccentricity" (2023). Astronomy: Faculty Publications, Smith College, Northampton, MA.
https://scholarworks.smith.edu/ast_facpubs/147
Comments
Archived as published.