Atmospheric Characterization and Further Orbital Modeling of κ Andromeda b
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Author
Uyama, Taichi
Currie, Thayne
Hori, Yasunori
De Rosa, Robert J.
Mede, Kyle
Brandt, Timothy D.

Kwon, Jungmi
Guyon, Olivier
Lozi, Julien
Jovanovic, Nemanja
Martinache, Frantz
Kudo, Tomoyuki

Tamura, Motohide
Kasdin, N. Jeremy
Groff, Tyler
Chilcote, Jeffrey
Hayashi, Masahiko

McElwain, Michael W.
Asensio-Torres, Ruben
Janson, Markus
Knapp, Gillian R.
Serabyn, Eugene
Affiliation
Univ Arizona, Steward ObservIssue Date
2020-01-07
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Taichi Uyama et al 2020 AJ 159 40Journal
ASTRONOMICAL JOURNALRights
Copyright © 2020. The American Astronomical Society. All rights reserved.Collection Information
This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at repository@u.library.arizona.edu.Abstract
We present kappa 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 kappa 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 kappa And b may have lower gravity than those previously reported. Atmospheric models lacking dust/clouds fail to reproduce its entire 1-4.7 mu m spectral energy distribution (SED), and cloudy atmosphere models with temperatures of similar to 1700-2000 K better match kappa And b data. Most well-fitting model comparisons favor 1700-1900 K, a surface gravity of log(g) similar to 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 kappa 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 kappa And b to a wide separation and high eccentricity. If three planets, including kappa And b, were born with coplanar orbits, and one of them was ejected by gravitational scattering, a potential inner companion with mass greater than or similar to 10 M-Jup could be located at less than or similar to 25 au.ISSN
0004-6256Version
Final published versionae974a485f413a2113503eed53cd6c53
10.3847/1538-3881/ab5afa