Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: First Empirical Determination of the Fe 10+ and Fe 13+ Freeze-in
  Distances in the Solar Corona   Heavy ions are markers of the physical processes responsible for the density
and temperature distribution throughout the fine scale magnetic structures that
define the shape of the solar corona. One of their properties, whose empirical
determination has remained elusive, is the 'freeze-in' distance (Rf) where they
reach fixed ionization states that are adhered to during their expansion with
the solar wind. We present the first empirical inference of Rf for Fe10+ and
Fe13+ derived from multi-wavelength imaging observations of the corresponding
FeXI (Fe10+) 789.2 nm and FeXIV (Fe13+) 530.3 nm emission acquired during the
2015 March 20 total solar eclipse. We find that the two ions freeze-in at
different heliocentric distances. In polar coronal holes Rf is around 1.45 Rs
for Fe10+ and below 1.25 Rs for Fe13+. Along open field lines in streamer
regions Rf ranges from 1.4 to 2 Rs for Fe10+ and from 1.5 to 2.2 Rs for Fe13+.
These first empirical Rf values: (1) reflect the differing plasma parameters
between coronal holes and streamers and structures within them, including
prominences and Coronal Mass Ejections (CMEs); (2) are well below the currently
quoted values derived from empirical model studies; and (3) place doubt on the
reliability of plasma diagnostics based on the assumption of ionization
equilibrium beyond 1.2 Rs.

16
The categories of this paper are: stat
13
The categories of this paper are: quant-ph
4
The categories of this paper are: cond-mat
17
The categories of this paper are: q-fin
28
The categories of this paper are: alg-geom
7
The categories of this paper are: hep-th
21
The categories of this paper are: adap-org
24
The categories of this paper are: dg-ga
29
The categories of this paper are: funct-an
36
The categories of this paper are: cmp-lg
30
The categories of this paper are: q-alg
3
The categories of this paper are: physics
12
The categories of this paper are: nucl-th
34
The categories of this paper are: chem-ph
32
The categories of this paper are: atom-ph
0
The categories of this paper are: hep-ph