Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Strong effects of time-dependent ionization in early SN 1987A   We study a time-dependent hydrogen ionization in the atmosphere of SN 1987A
during the first month after the explosion. The model includes kinetics of
hydrogen ionization and excitation, molecular hydrogen kinetics, and a
time-dependent energy balance. The primary strong effect of the time-dependent
ionization is the enhanced hydrogen ionization compared to the steady-state
model. The time-dependent ionization provides a sufficient population of
excited hydrogen levels to account for the observed H-alpha without invoking
the external Ni-56. We find that the Ba II 6142 A line in SN 1987A can be
reproduced for the LMC barium abundance. This resolves the long-standing
problem of the unacceptably high barium overabundance in SN 1987A. The key
missing factor that should be blamed for the "barium problem" is the
time-dependent ionization. The modelling of the H-alpha profile on day 4.64
indicates the ratio of the kinetic energy to the ejected mass about 0.83
10^{50} erg/Msun.

24
The categories of this paper are: dg-ga
0
The categories of this paper are: hep-ph
22
The categories of this paper are: chao-dyn
35
The categories of this paper are: mtrl-th
34
The categories of this paper are: chem-ph
15
The categories of this paper are: nucl-ex
20
The categories of this paper are: acc-phys
29
The categories of this paper are: funct-an
1
The categories of this paper are: cs
2
The categories of this paper are: math
30
The categories of this paper are: q-alg
26
The categories of this paper are: bayes-an
19
The categories of this paper are: eess
37
The categories of this paper are: supr-con
16
The categories of this paper are: stat
36
The categories of this paper are: cmp-lg