Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The multi-thermal chromosphere: inversions of ALMA and IRIS data   Numerical simulations of the solar chromosphere predict a diverse thermal
structure with both hot and cool regions. Observations of plage regions in
particular feature broader and brighter chromospheric lines, which suggest that
they are formed in hotter and denser conditions than in the quiet-Sun, but also
implies a non-thermal component whose source is unclear. We revisit the problem
of the stratification of temperature and microturbulence in plage now adding
millimeter continuum observations provided by ALMA to inversions of
near-ultraviolet IRIS spectra as a powerful new diagnostic to disentangle the
two parameters. We fit cool chromospheric holes and track the fast evolution of
compact mm brightenings in the plage region. We use the STiC non-LTE inversion
code to simultaneously fit real ultraviolet and millimeter spectra in order to
infer the thermodynamic parameters of the plasma. We confirm the anticipated
constraining potential of ALMA in non-LTE inversions of the solar chromosphere.
We find significant differences between the inversion results of IRIS data
alone compared to the results of a combination with the mm data: the IRIS+ALMA
inversions have increased contrast and temperature range, and tend to favor
lower values of microturbulence in the chromosphere of plage. The average
brightness temperature of the plage region at 1.25 mm is 8500 K, but the ALMA
maps also show much cooler ($\sim3000$ K) and hotter ($\sim11\,000$ K) evolving
features partially seen in other diagnostics. To explain the former, the
inversions require the existence of localized, low temperature regions in the
chromosphere where molecules such as CO could form. The hot features could
sustain such high temperatures due to non-equilibrium hydrogen ionization
effects in a shocked chromosphere - a scenario that is supported by
low-frequency shock wave patterns found in the MgII lines probed by IRIS.

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The categories of this paper are: q-bio
36
The categories of this paper are: cmp-lg
31
The categories of this paper are: ao-sci
14
The categories of this paper are: math-ph
37
The categories of this paper are: supr-con
4
The categories of this paper are: cond-mat
1
The categories of this paper are: cs
26
The categories of this paper are: bayes-an
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The categories of this paper are: stat
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The categories of this paper are: econ
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The categories of this paper are: alg-geom
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The categories of this paper are: patt-sol
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The categories of this paper are: math
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The categories of this paper are: plasm-ph
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The categories of this paper are: nlin
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The categories of this paper are: mtrl-th