Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The role of the charge state of PAHs in ultraviolet extinction   Aims: We explore the relation between charge state of polycyclic aromatic
hydrocarbons (PAHs) and extinction curve morphology. Methods: We fit extinction
curves with a dust model including core-mantle spherical particles of mixed
chemical composition (silicate core, $sp^2$ and $sp^3$ carbonaceous layers),
and an additional molecular component. We use exact methods to calculate the
extinction due to classical particles and accurate computed absorption spectra
of PAHs in different charge states, for the contribution due to the molecular
component, along a sample of five rather different lines of sight. Results: A
combination of classical dust particles and mixtures of real PAHs
satisfactorily matches the observed interstellar extinction curves. Variations
of the spectral properties of PAHs in different charge states produce changes
consistent with the varying relative strengths of the bump and non-linear
far-UV rise.

17
The categories of this paper are: q-fin
23
The categories of this paper are: solv-int
27
The categories of this paper are: comp-gas
2
The categories of this paper are: math
8
The categories of this paper are: hep-ex
7
The categories of this paper are: hep-th
21
The categories of this paper are: adap-org
22
The categories of this paper are: chao-dyn
26
The categories of this paper are: bayes-an
3
The categories of this paper are: physics
0
The categories of this paper are: hep-ph
12
The categories of this paper are: nucl-th
33
The categories of this paper are: plasm-ph
16
The categories of this paper are: stat
36
The categories of this paper are: cmp-lg
1
The categories of this paper are: cs