Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: KELT-19Ab: A P~4.6 Day Hot Jupiter Transiting a Likely Am Star with a
  Distant Stellar Companion   We present the discovery of the giant planet KELT-19Ab, which transits the
moderately bright $(\mathrm{V} \sim 9.9)$ A8V star TYC 764-1494-1 with an
orbital period of 4.61 days. We confirm the planetary nature of the companion
via a combination of radial velocities, which limit the mass to $<
4.1\,\mathrm{M_J}$ $(3\sigma)$, and a clear Doppler tomography signal, which
indicates a retrograde projected spin-orbit misalignment of $\lambda =
-179.7^{+3.7}_{-3.8}$ degrees. Global modeling indicates that the $\rm{T_{eff}}
=7500 \pm 110\,\mathrm{K}$ host star has $\mathrm{M_*} =
1.62^{+0.25}_{-0.20}\,\mathrm{M_\odot}$ and $\mathrm{R_*} = 1.83 \pm
0.10\,\mathrm{R_\odot}$. The planet has a radius of $\mathrm{R_P}=1.91 \pm
0.11\,\mathrm{R_J}$ and receives a stellar insolation flux of $\sim 3.2\times
10^{9}\,\mathrm{erg\,s^{-1}\,cm^{-2}}$, leading to an inferred equilibrium
temperature of $\rm{T_{EQ}} = \sim 1935\,\rm{K}$ assuming zero albedo and
complete heat redistribution. With a $v\sin{I_*}=84.8\pm
2.0\,\mathrm{km\,s^{-1}}$, the host is relatively slowly rotating compared to
other stars with similar effective temperatures, and it appears to be enhanced
in metallic elements but deficient in calcium, suggesting that it is likely an
Am star. KELT-19A would be the first detection of an Am host of a transiting
planet of which we are aware. Adaptive optics observations of the system reveal
the existence of a companion with late G9V/early K1V spectral type at a
projected separation of $\approx 160\,\mathrm{AU}$. Radial velocity
measurements indicate that this companion is bound. Most Am stars are known to
have stellar companions, which are often invoked to explain the relatively slow
rotation of the primary. In this case, the stellar companion is unlikely to
have caused the tidal braking of the primary. However, it may have emplaced the
transiting planetary companion via the Kozai-Lidov mechanism.

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The categories of this paper are: econ
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The categories of this paper are: stat
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The categories of this paper are: solv-int
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The categories of this paper are: adap-org
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The categories of this paper are: nlin
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The categories of this paper are: cmp-lg
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The categories of this paper are: chao-dyn
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The categories of this paper are: chem-ph
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The categories of this paper are: gr-qc
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The categories of this paper are: ao-sci
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The categories of this paper are: physics
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The categories of this paper are: cs
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The categories of this paper are: atom-ph
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The categories of this paper are: bayes-an
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The categories of this paper are: acc-phys
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The categories of this paper are: q-alg