Astronomy and Astrophysics – Astrophysics
Scientific paper
Dec 2009
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2009ap%26ss.324..199e&link_type=abstract
Astrophysics and Space Science, Volume 324, Issue 2-4, pp. 199-204
Astronomy and Astrophysics
Astrophysics
Scientific paper
Spatially resolved studies of star-forming regions show that the assumption of spherical geometry is not realistic in most cases, with a major complication posed by the gas being ionised by multiple non-centrally located stars or star clusters. Geometrical effects including the spatial configuration of ionising sources affect the temperature and ionisation structure of these regions. We try to isolate the effects of multiple non-centrally located stars, via the construction of 3D photoionisation models using the 3D Monte Carlo photoionisation code mocassin with very simple gas density distributions, but various spatial configurations for the ionisation sources. Emission-line spectra from H ii regions are often used to study the metallicity of star-forming regions, as well as for providing a constraint on temperatures and luminosities of the ionising sources. Empirical metallicity diagnostics must often be calibrated with the aid of photoionisation models. However, most studies so far have been carried out by assuming spherical or plane-parallel geometries, with major limitations on the allowed gas and dust density distributions and with the spatial distribution of multiple, non-centrally located ionising sources not being accounted for. We compare integrated emission-line spectra from our models and quantify any systematic errors caused by the simplifying assumption of a single, central location for all ionising sources. We find that the dependence of the metallicity indicators on the ionisation parameter causes a clear bias, due to the fact that models with a fully distributed configuration of stars always display lower ionisation parameters than their fully concentrated counterparts. The errors found imply that the geometrical distribution of ionisation sources may partly account for the large scatter in metallicities derived using model-calibrated empirical methods.
Bastian Nate
Ercolano Barbara
Stasinska Grazyna
No associations
LandOfFree
The effects of spatially distributed ionisation sources on the temperature structure of H ii regions 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 The effects of spatially distributed ionisation sources on the temperature structure of H ii regions, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The effects of spatially distributed ionisation sources on the temperature structure of H ii regions will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1882529