Radiation thermo-chemical models of protoplanetary disks II. Line diagnostics

Details Radiation thermo-chemical models of protoplanetary disks II. Line diagnostics Radiation thermo-chemical models of protoplanetary disks II. Line diagnostics

2009-11-10

arxiv.org/abs/0911.1949v1

Astronomy and Astrophysics

Astrophysics

Solar and Stellar Astrophysics

accepted for publication in A&A

Scientific paper

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.

Affiliated with

Also associated with

No associations

Rating

Radiation thermo-chemical models of protoplanetary disks II. Line diagnostics does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Radiation thermo-chemical models of protoplanetary disks II. Line diagnostics, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Radiation thermo-chemical models of protoplanetary disks II. Line diagnostics will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-51756