Astronomy and Astrophysics – Astrophysics – Solar and Stellar Astrophysics
Scientific paper
2009-06-03
Astrophys.J.Supp.183:179-196,2009
Astronomy and Astrophysics
Astrophysics
Solar and Stellar Astrophysics
Accepted by ApJS. 24 pages, 15 figures. A version with higher resolution images is available from http://www.astro.phys.ethz
Scientific paper
10.1088/0067-0049/183/2/179
Upcoming facilities such as the Herschel Space Observatory or ALMA will deliver a wealth of molecular line observations of young stellar objects (YSOs). Based on line fluxes, chemical abundances can then be estimated by radiative transfer calculations. To derive physical properties from abundances, the chemical network needs to be modeled and fitted to the observations. This modeling process is however computationally exceedingly demanding, particularly if in addition to density and temperature, far UV (FUV) irradiation, X-rays, and multi-dimensional geometry have to be considered. We develop a fast tool, suitable for various applications of chemical modeling in YSOs. A grid of the chemical composition of the gas having a density, temperature, FUV irradiation and X-ray flux is pre-calculated as a function of time. A specific interpolation approach is developed to reduce the database to a feasible size. Published models of AFGL 2591 are used to verify the accuracy of the method. A second benchmark test is carried out for FUV sensitive molecules. The novel method for chemical modeling is more than 250,000 times faster than direct modeling and agrees within a mean factor of 1.35. The tool is distributed for public use. In the course of devloping the method, the chemical evolution is explored: We find that X-ray chemistry in envelopes of YSOs can be reproduced by means of an enhanced cosmic-ray ionization rate. We further find that the abundance of CH+ in low-density gas with high ionization can be enhanced by the recombination of doubly ionized carbon (C++) and suggest a new value for the initial abundance of the main sulphur carrier in the hot-core.
Benz Arnold O.
Bruderer Simon
Doty Steven D.
No associations
LandOfFree
Chemical Modelling of Young Stellar Objects, I. Method and Benchmarks 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 Chemical Modelling of Young Stellar Objects, I. Method and Benchmarks, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Chemical Modelling of Young Stellar Objects, I. Method and Benchmarks will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-193226