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

Authors

• Sarah Blunt, Northwestern University
• W. O. Balmer, Johns Hopkins University
• J. J. Wang, Northwestern University
• S. Lacour, LESIA - Laboratoire d'Etudes Spatiales et d'Instrumentation en Astrophysique
• S. Petrus, Universidad de Valparaiso
• G. Bourdarot, Max Planck Institute for Extraterrestrial Physics
• J. Kammerer, Space Telescope Science Institute
• N. Pourré, Institut de Planétologie et d’Astrophysique de Grenoble (IPAG)
• E. Rickman, European Space Agency - ESA
• J. Shangguan, Max Planck Institute for Extraterrestrial Physics
• T. Winterhalder, European Southern Observatory
• R. Abuter, European Southern Observatory
• A. Amorim, Faculdade de Ciências da Universidade de Lisboa
• R. Asensio-Torres, Max Planck Institute for Astronomy
• M. Benisty, Institut de Planétologie et d’Astrophysique de Grenoble (IPAG)
• J. P. Berger, Institut de Planétologie et d’Astrophysique de Grenoble (IPAG)
• H. Beust, Institut de Planétologie et d’Astrophysique de Grenoble (IPAG)
• A. Boccaletti, LESIA - Laboratoire d'Etudes Spatiales et d'Instrumentation en Astrophysique
• A. Bohn, Sterrewacht Leiden
• M. Bonnefoy, Institut de Planétologie et d’Astrophysique de Grenoble (IPAG)
• H. Bonnet, European Southern Observatory
• W. Brandner, Max Planck Institute for Astronomy
• F. Cantalloube, Laboratoire d'Astrophysique de Marseille
• P. Caselli, Max Planck Institute for Extraterrestrial Physics
• B. Charnay, LESIA - Laboratoire d'Etudes Spatiales et d'Instrumentation en Astrophysique
• G. Chauvin, Institut de Planétologie et d’Astrophysique de Grenoble (IPAG)
• A. Chavez, Northwestern University
• E. Choquet, Laboratoire d'Astrophysique de Marseille
• V. Christiaens, Monash University
• Y. Clénet, LESIA - Laboratoire d'Etudes Spatiales et d'Instrumentation en Astrophysique
• et al, Various Institutions
• Kimberly Ward-Duong, Smith CollegeFollow

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

https://doi.org/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

Version

Version of Record

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