2001/05/17 by I. Kamp, Inga Kamp, Gerd-Jan van Zadelhoff +1 · 4 citations
Chemistry · Physics and Astronomy · #Astrophysics and Star Formation Studies #Molecular Spectroscopy and Structure #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1051/0004-6361:20010629
16 pages, 31 figures, A&A accepted May 4, 2001
arxiv created 2001/05/17 · openalex publication_date 2001/07/01 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/04
In circumstellar disks or shells it is often assumed that gas and dust temperatures are equal where the latter is determined by radiative equilibrium. This paper deals with the question whether this assumption is applicable for tenuous circumstellar disks around young A stars. In this paper the thin hydrostatic equilibrium models described by Kamp & Bertoldi ([CITE]) are combined with a detailed heating/cooling balance for the gas. The most important heating and cooling processes are heating through infrared pumping, heating due to the drift velocity of dust grains, and fine structure and molecular line cooling. Throughout the whole disk gas and dust are not efficiently coupled by collisions and hence their temperatures are quite different. Most of the gas in the disk models considered here stays well below 300 K. In the temperature range below 300 K the gas chemistry is not much affected by Tgas and therefore the simplifying approximation can be used for calculating the chemical structure of the disk. Nevertheless the gas temperature is important for the quantitative interpretation of observations, like fine structure and molecular lines.