Please note that eDoc will be permanently shut down in the first quarter of 2021!      Home News About Us Contact Contributors Disclaimer Privacy Policy Help FAQ

Home
Search
Quick Search
Advanced
Fulltext
Browse
Collections
Persons
My eDoc
Session History
Login
Name:
Password:
Documentation
Help
Support Wiki
Direct access to
document ID:


          Institute: MPI für Radioastronomie     Collection: Publikationen des MPI für Radioastronomie     Display Documents



ID: 12294.0, MPI für Radioastronomie / Publikationen des MPI für Radioastronomie
Numerical methods for non-LTE line radiative transfer: Performance and convergence characteristics
Authors:van Zadelhoff, G. J.; Dullemond, C. P.; van der Tak, F. F. S.; Yates, J. A.; Doty, S. D.; Ossenkopf, V.; Hogerheijde, M. R.; Juvela, M.; Wiesemeyer, H.; Schöier, F. L.
Language:English
Date of Publication (YYYY-MM-DD):2002-11
Title of Journal:Astronomy & Astrophysics
Journal Abbrev.:Astron. Astrophys.
Volume:395
Issue / Number:1
Start Page:373
End Page:384
Review Status:Peer-review
Audience:Experts Only
Abstract / Description:Comparison is made between a number of independent computer programs for radiative transfer in molecular rotational lines. The test models are spherically symmetric circumstellar envelopes with a given density and temperature profile. The first two test models have a simple power law density distribution, constant temperature and a fictive 2-level molecule, while the other two test models consist of an inside- out collapsing envelope observed in rotational transitions of HCO+. For the 2-level molecule test problems all codes agree well to within 0.2%, comparable to the accuracy of the individual codes, for low optical depth and up to 2% for high optical depths (tau = 4800). The problem of the collapsing cloud in HCO+ has a larger spread in results, ranging up to 12% for the J = 4 population. The spread is largest at the radius where the transition from collisional to radiative excitation occurs. The resulting line profiles for the HCO+ J = 4-3 transition agree to within 10%, i.e., within the calibration accuracy of most current telescopes. The comparison project and the results described in this paper provide a benchmark for future code development, and give an indication of the typical accuracy of present day calculations of molecular line transfer.
Free Keywords:stars : formation; molecular processes
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Radioastronomie
External Affiliations:Leiden Observ, POB 9513, NL-2300 RA Leiden, Netherlands; Leiden Observ, NL-2300 RA Leiden, Netherlands; Max Planck Inst Astrophys, D-85741 Garching, Germany; Max Planck Inst Radioastron, D-53121 Bonn, Germany; Univ Coll London, London WC1E 6BT, England; Denison Univ, Dept Phys & Astron, Granville, OH 43023 USA; Univ Cologne, Inst Phys 1, D-50937 Cologne, Germany; Univ Arizona, Steward Observ, Tucson, AZ 85721 USA; Univ Helsinki, Helsinki Univ Observ, FIN-00014 Helsinki, Finland; Inst Radio Astron Millimetr, F-38406 St Martin Dheres, France
Identifiers:ISI:000179048000043
ISSN:0004-6361
The scope and number of records on eDoc is subject to the collection policies defined by each institute - see "info" button in the collection browse view.