Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Dust and molecules in extra-galactic planetary nebulae   Extra-galactic planetary nebulae (PNe) permit the study of dust and molecules
in metallicity environments other than the Galaxy. Their known distances lower
the number of free parameters in the observations vs. models comparison,
providing strong constraints on the gas-phase and solid-state astrochemistry
models. Observations of PNe in the Galaxy and other Local Group galaxies such
as the Magellanic Clouds (MC) provide evidence that metallicity affects the
production of dust as well as the formation of complex organic molecules and
inorganic solid-state compounds in their circumstellar envelopes. In
particular, the lower metallicity MC environments seem to be less favorable to
dust production and the frequency of carbonaceous dust features and complex
fullerene molecules is generally higher with decreasing metallicity. Here, I
present an observational review of the dust and molecular content in
extra-galactic PNe as compared to their higher metallicity Galactic
counterparts. A special attention is given to the level of dust processing and
the formation of complex organic molecules (e.g., polycyclic aromatic
hydrocarbons, fullerenes, and graphene precursors) depending on metallicity.

31
The categories of this paper are: ao-sci
36
The categories of this paper are: cmp-lg
16
The categories of this paper are: stat
11
The categories of this paper are: hep-lat
10
The categories of this paper are: q-bio
35
The categories of this paper are: mtrl-th
3
The categories of this paper are: physics
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
18
The categories of this paper are: econ
19
The categories of this paper are: eess
13
The categories of this paper are: quant-ph
12
The categories of this paper are: nucl-th
30
The categories of this paper are: q-alg
37
The categories of this paper are: supr-con