CaltechAUTHORS
Published February 2020 | Version Published + Accepted Version
Journal Article Open

Atmospheric Characterization and Further Orbital Modeling of κ Andromeda b

Creators

  • 1. ROR icon Infrared Processing and Analysis Center
  • 2. ROR icon NASA Exoplanet Science Institute
  • 3. ROR icon University of Tokyo
  • 4. ROR icon National Astronomical Observatory of Japan
  • 5. ROR icon Ames Research Center
  • 6. ROR icon University of Hawaii at Hilo
  • 7. ROR icon Eureka Scientific
  • 8. ROR icon Astrobiology Center
  • 9. ROR icon Kavli Institute for Particle Astrophysics and Cosmology
  • 10. ROR icon University of California, Santa Barbara
  • 11. ROR icon University of Arizona
  • 12. ROR icon California Institute of Technology
  • 13. ROR icon Observatoire de la Côte d'Azur
  • 14. ROR icon Princeton University
  • 15. ROR icon Goddard Space Flight Center
  • 16. ROR icon University of Notre Dame
  • 17. ROR icon Stockholm University
  • 18. ROR icon Jet Propulsion Lab

Abstract

We present κ Andromeda b's photometry and astrometry taken with Subaru/SCExAO+HiCIAO and Keck/NIRC2, combined with recently published SCExAO/CHARIS low-resolution spectroscopy and published thermal infrared photometry to further constrain the companion's atmospheric properties and orbit. The Y/Y−K colors of κ And b are redder than field dwarfs, consistent with its youth and lower gravity. Empirical comparisons of its Y-band photometry and CHARIS spectrum to a large spectral library of isolated field dwarfs reaffirm the conclusion from Currie et al. that it likely has a low gravity but admit a wider range of most plausible spectral types (L0–L2). Our gravitational classification also suggests that the best-fit objects for κ And b may have lower gravity than those previously reported. Atmospheric models lacking dust/clouds fail to reproduce its entire 1–4.7 μm spectral energy distribution (SED), and cloudy atmosphere models with temperatures of ~1700–2000 K better match κ And b data. Most well-fitting model comparisons favor 1700–1900 K, a surface gravity of log(g) ~ 4–4.5, and a radius of 1.3–1.6 R_(Jup); the best-fit model (DRIFT-PHOENIX) yields the coolest and lowest-gravity values: T_(eff) = 1700 K and log g = 4.0. An update to κ And b's orbit with ExoSOFT using new astrometry spanning 7 yr reaffirms its high eccentricity (0.77 ± 0.08). We consider a scenario where unseen companions are responsible for scattering κ And b to a wide separation and high eccentricity. If three planets, including κ And b, were born with coplanar orbits, and one of them was ejected by gravitational scattering, a potential inner companion with mass ≳10 M_(Jup) could be located at ≾25 au.

Additional Information

© 2020 The American Astronomical Society. Received 2019 August 12; revised 2019 November 16; accepted 2019 November 21; published 2020 January 7. The authors would like to thank the anonymous referees for their constructive comments and suggestions to improve the quality of the paper. This paper is based in part on data collected at the Subaru Telescope and obtained from SMOKA, which is operated by the Astronomy Data Center, National Astronomical Observatory of Japan. Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The observatory was made possible by the generous financial support of the W. M. Keck Foundation. This work presents results from the European Space Agency (ESA) space mission Gaia. The Gaia data are being processed by the Gaia Data Processing and Analysis Consortium (DPAC). Funding for the DPAC is provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement (MLA). The Gaia mission website is https://www.cosmos.esa.int/gaia. The Gaia archive website is https://archives.esac.esa.int/gaia. T.U. acknowledges a JSPS overseas research fellowship. This work was supported by JSPS KAKENHI grant Nos. JP17J00934, 15H02063, and 18H05442. T.C. was supported by a NASA Senior Postdoctoral Fellowship and NASA/Keck grant LK-2663-948181; R.D.R. was supported by NASA grant NSSC17K0535. The development of SCExAO was supported by JSPS (Grant-in-Aid for Research Nos. 23340051, 26220704, and 23103002), the Astrobiology Center of NINS, Japan, the Mt. Cuba Foundation, and the director's contingency fund at the Subaru Telescope. CHARIS was developed with the support of Grant-in-Aid for Scientific Research on Innovative Areas No. 2302. The authors wish to acknowledge the very significant cultural role and reverence that the summit of Maunakea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain.

Attached Files

Published - Uyama_2020_AJ_159_40.pdf

Accepted Version - 1911.09758.pdf

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1911.09758.pdf

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Additional details

Additional titles

Alternative title
Atmospheric Characterization and Further Orbital Modeling of κ And b

Identifiers

Eprint ID
100545
Resolver ID
CaltechAUTHORS:20200107-145830087

Related works

Describes
https://arxiv.org/abs/1911.09758 (URL)

Funding

W. M. Keck Foundation
Gaia Multilateral Agreement
Japan Society for the Promotion of Science (JSPS)
JP17J00934
Japan Society for the Promotion of Science (JSPS)
15H02063
Japan Society for the Promotion of Science (JSPS)
18H05442
NASA
LK-2663-948181
NASA
NSSC17K0535
Japan Society for the Promotion of Science (JSPS)
23340051
Japan Society for the Promotion of Science (JSPS)
26220704
Japan Society for the Promotion of Science (JSPS)
23103002
National Institute of Natural Sciences (NINS)
Mt. Cuba Astronomical Foundation
Subaru Telescope
Japan Society for the Promotion of Science (JSPS)
2302

Dates

Created
2020-01-08
Created from EPrint's datestamp field
Updated
2021-11-16
Created from EPrint's last_modified field

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Caltech groups
Infrared Processing and Analysis Center (IPAC)