8 papers · 1 filter
On the reliability of mass-loss-rate estimates for AGB stars
Sofia Ramstedt, Fredrik L. Schoeier, Hans Olofsson +1
In the recent literature there has been some doubt as to the reliability of CO multi-transitional line observations as a mass-loss-rate estimator for AGB stars. Mass-loss rates for…
An atomic and molecular database for analysis of submillimetre line observations
F. L. Schoeier, F. F. S. van der Tak, E. F. van Dishoeck +1
Atomic and molecular data for the transitions of a number of astrophysically interesting species are summarized, including energy levels, statistical weights, Einstein A-coefficien…
Molecular abundances in carbon-rich circumstellar envelopes
P. M. Woods, F. L. Schoeier, L. -A. Nyman +1
We present a millimetre molecular line survey of seven high mass loss rate carbon stars in both the northern and southern skies. A total of 196 emission lines (47 transitions) from…
Numerical methods for non-LTE line radiative transfer: Performance and convergence characteristics
G. -J. van Zadelhoff, C. P. Dullemond, F. F. S. van der Tak +7
Comparison is made between a number of independent computer programs for radiative transfer in molecular rotational lines. The test models are spherically symmetric circumstellar e…
Mass loss rates of a sample of irregular and semiregular M-type AGB-variables
H. Olofsson, D. Gonzalez Delgado, F. Kerschbaum +1
We have determined mass loss rates and gas expansion velocities for a sample of 69 M-type irregular (IRV; 22 objects) and semiregular (SRV; 47 objects) AGB-variables using a radiat…
Does IRAS 16293-2422 have a hot core? Chemical inventory and abundance changes in its protostellar environment
F. L. Schoeier, J. K. Jorgensen, E. F. van Dishoeck +1
A detailed radiative transfer analysis of the observed continuum and molecular line emission toward the deeply embedded young stellar object IRAS 16293-2422 is performed. The conti…