Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Computation of the transmitted and polarized scattered fluxes by the
  exoplanet HD 189733b in X-rays   Thousands of exoplanets have been detected, but only one exoplanetary transit
was potentially observed in X-rays from HD189733A. What makes the detection of
exoplanets so difficult in this band? To answer this question, we run
Monte-Carlo radiative transfer simulations to estimate the amount of X-ray flux
reprocessed by HD189733b. Despite its extended evaporating-atmosphere, we find
that the X-ray absorption radius of HD189733b at 0.7keV, the mean energy of the
photons detected in the 0.25--2 keV energy band by XMM-Newton, is $\sim$1.01
times the planetary radius for an atmosphere of atomic Hydrogen and Helium
(including ions), and produces a maximum depth of $\sim$2.1% at
$\sim$$\pm46$~min from the center of the planetary transit on the geometrically
thick and optically thin corona. We compute numerically in the 0.25--2keV
energy band that this maximum depth is only of $\sim$1.6% at $\sim$$\pm47$~min
from the transit center, and little sensitive to the metal abundance assuming
that adding metals in the atmosphere would not dramatically change the
density-temperature profile. Regarding a direct detection of HD189733b in
X-rays, we find that the amount of flux reprocessed by the exoplanetary
atmosphere varies with the orbital phase, spanning between 3--5 orders of
magnitude fainter than the flux of the primary star. Additionally, the degree
of linear polarization emerging from HD 189733b is $<$0.003%, with maximums
detected near planetary greatest elongations. This implies that both the
modulation of the X-ray flux with the orbital phase and the scattered-induced
continuum polarization cannot be observed with current X-ray facilities.

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The categories of this paper are: nucl-th
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The categories of this paper are: bayes-an
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The categories of this paper are: solv-int
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The categories of this paper are: atom-ph
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The categories of this paper are: math-ph
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The categories of this paper are: econ
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The categories of this paper are: comp-gas
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The categories of this paper are: q-fin
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The categories of this paper are: chem-ph
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The categories of this paper are: chao-dyn
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The categories of this paper are: funct-an
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The categories of this paper are: gr-qc
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The categories of this paper are: supr-con
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The categories of this paper are: mtrl-th
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The categories of this paper are: hep-ex
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The categories of this paper are: stat