Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: ISO spectroscopy of circumstellar dust in 14 Herbig Ae/Be systems:
  towards an understanding of dust processing   We present Infrared Space Observatory (ISO) spectra of fourteen isolated
Herbig Ae/Be (HAEBE) stars, to study the characteristics of their circumstellar
dust. These spectra show large star-to-star differences, in the emission
features of both carbon-rich and oxygen-rich dust grains. The IR spectra were
combined with photometric data ranging from the UV through the optical into the
sub-mm region. We defined two key groups, based upon the spectral shape of the
infrared region. The derived results can be summarized as follows: (1) the
continuum of the IR to sub-mm region of all stars can be reconstructed by the
sum of a power-law and a cool component, which can be represented by a black
body. Possible locations for these components are an optically thick,
geometrically thin disc (power-law component) and an optically thin flared
region (black body); (2) all stars have a substantial amount of cold dust
around them, independent of the amount of mid-IR excess they show; (3) also the
near-IR excess is unrelated to the mid-IR excess, indicating different
composition/location of the emitting material; (4) remarkably, some sources
lack the silicate bands; (5) apart from amorphous silicates, we find evidence
for crystalline silicates in several stars, some of which are new detections;
(6) PAH bands are present in at least 50% of our sample, and their appearance
is slightly different from PAHs in the ISM; (7) PAH bands are, with one
exception, not present in sources which only show a power-law continuum in the
IR; their presence is unrelated to the presence of the silicate bands; (8) the
dust in HAEBE stars shows strong evidence for coagulation; this dust processing
is unrelated to any of the central star properties (such as age, spectral type
and activity).

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The categories of this paper are: comp-gas
21
The categories of this paper are: adap-org
36
The categories of this paper are: cmp-lg
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The categories of this paper are: chao-dyn
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The categories of this paper are: mtrl-th
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The categories of this paper are: patt-sol
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The categories of this paper are: nucl-ex
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The categories of this paper are: dg-ga
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The categories of this paper are: supr-con
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The categories of this paper are: physics
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The categories of this paper are: gr-qc
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The categories of this paper are: nlin
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The categories of this paper are: hep-th
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The categories of this paper are: eess
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The categories of this paper are: acc-phys
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The categories of this paper are: stat