Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Hot DA white dwarf model atmosphere calculations: Including improved Ni
  PI cross sections   To calculate realistic models of objects with Ni in their atmospheres,
accurate atomic data for the relevant ionization stages needs to be included in
model atmosphere calculations. In the context of white dwarf stars, we
investigate the effect of changing the Ni {\sc iv}-{\sc vi} bound-bound and
bound-free atomic data has on model atmosphere calculations. Models including
PICS calculated with {\sc autostructure} show significant flux attenuation of
up to $\sim 80$\% shortward of 180\AA\, in the EUV region compared to a model
using hydrogenic PICS. Comparatively, models including a larger set of Ni
transitions left the EUV, UV, and optical continua unaffected. We use models
calculated with permutations of this atomic data to test for potential changes
to measured metal abundances of the hot DA white dwarf G191-B2B. Models
including {\sc autostructure} PICS were found to change the abundances of N and
O by as much as $\sim 22$\% compared to models using hydrogenic PICS, but
heavier species were relatively unaffected. Models including {\sc
autostructure} PICS caused the abundances of N/O {\sc iv} and {\sc v} to
diverge. This is because the increased opacity in the {\sc autostructure} PICS
model causes these charge states to form higher in the atmosphere, moreso for
N/O {\sc v}. Models using an extended line list caused significant changes to
the Ni {\sc iv}-{\sc v} abundances. While both PICS and an extended line list
cause changes in both synthetic spectra and measured abundances, the biggest
changes are caused by using {\sc autostructure} PICS for Ni.

16
The categories of this paper are: stat
28
The categories of this paper are: alg-geom
14
The categories of this paper are: math-ph
13
The categories of this paper are: quant-ph
19
The categories of this paper are: eess
23
The categories of this paper are: solv-int
12
The categories of this paper are: nucl-th
17
The categories of this paper are: q-fin
25
The categories of this paper are: patt-sol
37
The categories of this paper are: supr-con
15
The categories of this paper are: nucl-ex
36
The categories of this paper are: cmp-lg
32
The categories of this paper are: atom-ph
20
The categories of this paper are: acc-phys
26
The categories of this paper are: bayes-an
10
The categories of this paper are: q-bio