Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: UV Exoplanet Transmission Spectral Features as Probes of Metals and
  Rainout   The low-resolution transmission spectra of ultra-hot Jupiters observed
shortward of 0.5 microns indicate strong absorption at short-wavelengths.
Previous explanations have included scattering, photochemistry, escaping
metals, and disequilibrium chemistry. In this Letter, we show that slopes and
features shortward of 0.5 microns can be caused by opacity not commonly
considered in atmosphere models of exoplanets but guaranteed to be present if
conditions are near chemical equilibrium including Fe I, Fe II, Ti I, Ni I, Ca
I, Ca II, and SiO. Even relatively trace species (e.g., Cr I and Mn I) can
contribute through strong lines in the UV and blue-optical. Using the PHOENIX
atmosphere model, we describe how the short-wavelength transit spectrum varies
with equilibrium temperature between 1000 K and 4000 K, as well as the effect
that the rainout of condensates has at these wavelengths. We define two
spectral indices to quantify the strength of the NUV and blue absorption
compared to that in the red-optical, finding that the NUV transit depth will
significantly exceed the transit depth from Rayleigh scattering alone for all
hot Jupiters down to around 1000 K. In the blue-optical, hot Jupiters warmer
than 2000 K will have transit depths larger than that from Rayleigh scattering,
but below 2000 K, Rayleigh scattering can dominate, if present. We further show
that these spectral indices may be used to trace the effects of rainout. We
then compare our simulated transit spectra to existing observations of
WASP-12b, WASP-33b, WASP-76b, and WASP-121b.

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The categories of this paper are: eess
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The categories of this paper are: math-ph
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The categories of this paper are: q-alg
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The categories of this paper are: hep-lat
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The categories of this paper are: chem-ph
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The categories of this paper are: hep-ex
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The categories of this paper are: cs
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The categories of this paper are: gr-qc
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The categories of this paper are: hep-ph
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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: stat
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The categories of this paper are: nucl-ex
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The categories of this paper are: physics
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The categories of this paper are: bayes-an
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The categories of this paper are: quant-ph