Atmospheric Characterization and Further Orbital Modeling of $kappa$ And b. (arXiv:1911.09758v1 [astro-ph.EP])
<a href="http://arxiv.org/find/astro-ph/1/au:+Uyama_T/0/1/0/all/0/1">Taichi Uyama</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Currie_T/0/1/0/all/0/1">Thayne Currie</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hori_Y/0/1/0/all/0/1">Yasunori Hori</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Rosa_R/0/1/0/all/0/1">Robert J. De Rosa</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Mede_K/0/1/0/all/0/1">Kyle Mede</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Brandt_T/0/1/0/all/0/1">Timothy D. Brandt</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Guyon_O/0/1/0/all/0/1">Olivier Guyon</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Lozi_J/0/1/0/all/0/1">Julien Lozi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Jovanovic_N/0/1/0/all/0/1">Nemanja Jovanovic</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Martinache_F/0/1/0/all/0/1">Frantz Martinache</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kudo_T/0/1/0/all/0/1">Tomoyuki Kudo</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Tamura_M/0/1/0/all/0/1">Motohide Tamura</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Groff_T/0/1/0/all/0/1">Tyler Groff</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Chilcote_J/0/1/0/all/0/1">Jeffrey Chilcote</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hayashi_M/0/1/0/all/0/1">Masahiko Hayashi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+McElwain_M/0/1/0/all/0/1">Michael W. McElwain</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Asensio_Torres_R/0/1/0/all/0/1">Ruben Asensio-Torres</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Janson_M/0/1/0/all/0/1">Markus Janson</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Knapp_G/0/1/0/all/0/1">Gillian R. Knapp</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kwon_J/0/1/0/all/0/1">Jungmi Kwon</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Serabyn_E/0/1/0/all/0/1">Eugene Serabyn</a>
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. $kappa$ And b’s Y/Y-K colors 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. (2018) 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, cloudy atmosphere models with temperatures of
$sim$ 1700–2000 $K$ better match $kappa$ And b data. Most well-fitting model
comparisons favor 1700–1900 $K$, a surface gravity of log(g) $sim$ 4–4.5,
and a radius of 1.3–1.6,$R_{rm Jup}$; the best-fit model (DRIFT-Phoenix)
yields the coolest and lowest-gravity values: $T_{rm eff}$=1700 K and $log
g$=4.0. An update to $kappa$ And b’s orbit with ExoSOFT using new astrometry
spanning seven years reaffirms its high eccentricity ($0.77pm0.08$). 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
$gtrsim10M_{rm Jup}$ could be located at $lesssim$ 25 au.
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. $kappa$ And b’s Y/Y-K colors 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. (2018) 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, cloudy atmosphere models with temperatures of
$sim$ 1700–2000 $K$ better match $kappa$ And b data. Most well-fitting model
comparisons favor 1700–1900 $K$, a surface gravity of log(g) $sim$ 4–4.5,
and a radius of 1.3–1.6,$R_{rm Jup}$; the best-fit model (DRIFT-Phoenix)
yields the coolest and lowest-gravity values: $T_{rm eff}$=1700 K and $log
g$=4.0. An update to $kappa$ And b’s orbit with ExoSOFT using new astrometry
spanning seven years reaffirms its high eccentricity ($0.77pm0.08$). 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
$gtrsim10M_{rm Jup}$ could be located at $lesssim$ 25 au.
http://arxiv.org/icons/sfx.gif
