Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Radiation thermo-chemical models of protoplanetary disks II. Line
  diagnostics   Methods. We use the recently developed disk code ProDiMo to calculate the
physico-chemical structure of protoplanetary disks and apply the Monte-Carlo
line radiative transfer code RATRAN to predict observable line profiles and
fluxes. We consider a series of Herbig Ae type disk models ranging from 10^-6
M_Sun to 2.2 10^-2 M_Sun (between 0.5 and 700 AU) to discuss the dependency of
the line fluxes and ratios on disk mass for otherwise fixed disk parameters.
Results. We find the [CII] 157.7 mum line to originate in LTE from the surface
layers of the disk, where Tg > Td . The total emission is dominated by surface
area and hence depends strongly on disk outer radius. The [OI] lines can be
very bright (> 10^-16 W/m^2) and form in slightly deeper and closer regions
under non-LTE conditions. The high-excitation [OI] 145.5 mum line, which has a
larger critical density, decreases more rapidly with disk mass than the 63.2
mum line. Therefore, the [OI] 63.2 mum/145.5 mum ratio is a promising disk mass
indicator, especially as it is independent of disk outer radius for Rout > 200
AU. CO is abundant only in deeper layers A_V >~ 0.05. For too low disk masses
(M_disk <~10^-4 M_Sun) the dust starts to become transparent, and CO is almost
completely photo-dissociated. For masses larger than that the lines are an
excellent independent tracer of disk outer radius and can break the outer
radius degeneracy in the [OI] 63.2 mum/[CII]157.7 mum line ratio. Conclusions.
The far-IR fine-structure lines of [CII] and [OI] observable with Herschel
provide a promising tool to measure the disk gas mass, although they are mainly
generated in the atomic surface layers. In spatially unresolved observations,
none of these lines carry much information about the inner, possibly hot
regions < 30 AU.

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The categories of this paper are: math-ph
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The categories of this paper are: plasm-ph
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The categories of this paper are: quant-ph
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The categories of this paper are: hep-ph
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The categories of this paper are: nlin
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The categories of this paper are: gr-qc
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The categories of this paper are: comp-gas
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The categories of this paper are: math
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The categories of this paper are: alg-geom
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The categories of this paper are: q-alg
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The categories of this paper are: chao-dyn
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The categories of this paper are: adap-org
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The categories of this paper are: funct-an
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The categories of this paper are: cond-mat
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The categories of this paper are: physics
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The categories of this paper are: q-fin