Photoionization models for PNe with inhomogeneous chemical composition

Details Photoionization models for PNe with inhomogeneous chemical composition Photoionization models for PNe with inhomogeneous chemical composition

Nov 2000

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2000ign..confe..46p&link_type=abstract

Ionized Gaseous Nebulae. Mexico City November 21- 24, 2000, meeting abstract

Computer Science

Scientific paper

It is well known that, using standard methods, planetary nebula abundances derived from optical recombination lines are often larger than those derived from collisionally excited lines. Considering the archetypal case of NGC 6153, in which the discrepancy amounts to a factor 10, it is shown that photoionization models including two components with different abundances can account for most of the numerous spectroscopic data available from UV to far-IR within observational uncertainties. Gas pressure is about the same in both components, suggesting that small, cold, ionized clumps, highly enriched in CNONe (factor ~ 20 by mass) and deficient in H, are embedded in a gas of more usual composition. The "t2 formalism" describing temperature fluctuations around a mean value is not applicable to nebulae with strongly fluctuating abundances. The total mass of the clumps is small and the average abundances are relatively close to those of the "normal" component. Thus the recombination line ratios do not reflect faithfully the actual average abundance ratios. In particular the helium abundance, very high in NGC 6153 according to conventional analyses, is currently left undetermined. More generally, fluctuations of composition within planetary nebulae will lead to overestimating the helium abundance. Deep multiwavelength observations and detailed photoionization models are necessary to obtain reliable abundances.

Affiliated with

Also associated with

No associations

Rating

Photoionization models for PNe with inhomogeneous chemical composition 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 Photoionization models for PNe with inhomogeneous chemical composition, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Photoionization models for PNe with inhomogeneous chemical composition will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1613269