Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Observational study of chromospheric heating by acoustic waves   Aims. To investigate the role of acoustic and magneto-acoustic waves in
heating the solar chromosphere, observations in strong chromospheric lines are
analyzed by comparing the deposited acoustic-energy flux with the total
integrated radiative losses.
  Methods. Quiet-Sun and weak-plage regions were observed in the Ca II 854.2 nm
and H-alpha lines with the Fast Imaging Solar Spectrograph (FISS) at the 1.6-m
Goode Solar Telescope (GST) on 2019 October 3 and in the H-alpha and H-beta
lines with the echelle spectrograph attached to the Vacuum Tower Telescope
(VTT) on 2018 December 11 and 2019 June 6. The deposited acoustic energy flux
at frequencies up to 20 mHz was derived from Doppler velocities observed in
line centers and wings. Radiative losses were computed by means of a set of
scaled non-LTE 1D hydrostatic semi-empirical models obtained by fitting
synthetic to observed line profiles.
  Results. In the middle chromosphere (h = 1000-1400 km), the radiative losses
can be fully balanced by the deposited acoustic energy flux in a quiet-Sun
region. In the upper chromosphere (h > 1400 km), the deposited acoustic flux is
small compared to the radiative losses in quiet as well as in plage regions.
The crucial parameter determining the amount of deposited acoustic flux is the
gas density at a given height.
  Conclusions. The acoustic energy flux is efficiently deposited in the middle
chromosphere, where the density of gas is sufficiently high. About 90% of the
available acoustic energy flux in the quiet-Sun region is deposited in these
layers, and thus it is a major contributor to the radiative losses of the
middle chromosphere. In the upper chromosphere, the deposited acoustic flux is
too low, so that other heating mechanisms have to act to balance the radiative
cooling.

17
The categories of this paper are: q-fin
10
The categories of this paper are: q-bio
0
The categories of this paper are: hep-ph
21
The categories of this paper are: adap-org
9
The categories of this paper are: nlin
35
The categories of this paper are: mtrl-th
15
The categories of this paper are: nucl-ex
12
The categories of this paper are: nucl-th
16
The categories of this paper are: stat
37
The categories of this paper are: supr-con
13
The categories of this paper are: quant-ph
11
The categories of this paper are: hep-lat
27
The categories of this paper are: comp-gas
1
The categories of this paper are: cs
19
The categories of this paper are: eess
7
The categories of this paper are: hep-th