Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The dusty Nebula surrounding HR Car: a Spitzer view   We present mid-IR observations of the Galactic Luminous Blue Variable (LBV)
HR Car and its associated nebula carried out with the Spitzer Space Telescope
using both IRAC and IRS, as part of a GTO program aimed to study stellar ejecta
from evolved stars. Our observations reveal a rich mid-IR spectrum of the inner
nebula showing both solid state and atomic gas signatures. Strong
low-excitation atomic fine structure lines such as $ 26.0 \mu$m [\ion{Fe}{2}]
and $ 34.8 \mu$m [\ion{Si}{2}], indicate, for the first time, the presence of a
PDR in this object class. While the physics and chemistry of the low-excitation
gas appears to be dominated by photodissociation, a possible contribution due
to shocks can be inferred from the evidence of gas phase Fe abundance
enhancement. The presence of amorphous silicates, inferred from the observed
characteristic broad feature at $10 \mu$m located in the inner nebula, suggests
that dust has formed during the LBV outburst. This is in contrast with the
detection of crystalline dust in other probably more evolved Galactic LBVs,
which is similar to the crystalline dust observed in red supergiants. This has
been considered to be evidence of dust production during evolutionary phases
prior to the outburst.

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The categories of this paper are: hep-ex
37
The categories of this paper are: supr-con
22
The categories of this paper are: chao-dyn
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The categories of this paper are: nlin
0
The categories of this paper are: hep-ph
31
The categories of this paper are: ao-sci
25
The categories of this paper are: patt-sol
16
The categories of this paper are: stat
28
The categories of this paper are: alg-geom
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The categories of this paper are: physics
1
The categories of this paper are: cs
19
The categories of this paper are: eess
29
The categories of this paper are: funct-an
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The categories of this paper are: nucl-ex
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The categories of this paper are: plasm-ph
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The categories of this paper are: nucl-th