Continuum and line modelling of discs around young stars. I. 300000 disc models for Herschel/GASPS

TL;DR

This study presents an extensive grid of 300,000 circumstellar disc models combining thermo-chemical and radiative transfer codes, to analyze how various parameters influence observable line and continuum emissions in young star discs.

Contribution

It introduces a comprehensive model grid for young star discs, systematically varying key parameters to aid in interpreting Herschel GASPS data and understanding disc properties.

Findings

Line fluxes strongly depend on UV excess and disc flaring.

A significant fraction of models predict detectable [OI] and [CII] lines.

Disc gas mass can potentially be inferred from line observations.

Abstract

We have combined the thermo-chemical disc code ProDiMo with the Monte Carlo radiative transfer code MCFOST to calculate a grid of ~300000 circumstellar disc models, systematically varying 11 stellar, disc and dust parameters including the total disc mass, several disc shape parameters and the dust-to-gas ratio. For each model, dust continuum and line radiative transfer calculations are carried out for 29 far IR, sub-mm and mm lines of [OI], [CII], 12CO and o/p-H2O under 5 inclinations. The grid allows to study the influence of the input parameters on the observables, to make statistical predictions for different types of circumstellar discs, and to find systematic trends and correlations between the parameters, the continuum fluxes, and the line fluxes. The model grid, comprising the calculated disc temperatures and chemical structures, the computed SEDs, line fluxes and profiles, will be used in particular for the data interpretation of the Herschel open time key programme GASPS. The calculated line fluxes show a strong dependence on the assumed UV excess of the central star, and on the disc flaring. The fraction of models predicting [OI] and [CII] fine-structure lines fluxes above Herschel/PACS and Spica/SAFARI detection limits are calculated as function of disc mass. The possibility of deriving the disc gas mass from line observations is discussed.