The elemental abundances in halo planetary nebulae
Abstract
Elemental abundances in halo planetary nebulae are studied by constructing a thick photoionization model (PIM) as described by Aldrovandi and Stasinska (1978). The input parameters of the model are the ionizing source spectrum, the distribution of the gas density, and its chemical composition. Also considered are the charge exchange reactions between ions and neutral H, while information about the ionizing spectrum are obtained from the line intensity ratio He II 4686/H beta. For the halo planetaries K648, 49 plus 88 deg 1, and 108 minus 76 deg 1, the abundance values obtained from the PIMs are shown and are generally less than those obtained by Hawley and Miller (1977), while the carbon abundance is generally high.
- Publication:
-
Reunion Astronomica Regional Latinoamericana
- Pub Date:
- 1979
- Bibcode:
- 1979rarl.conf..171A
- Keywords:
-
- Abundance;
- Charge Exchange;
- H Beta Line;
- Photoionization;
- Planetary Composition;
- Planetary Nebulae;
- Carbon;
- Helium;
- Hydrogen Clouds;
- Hydrogen Ions;
- Line Spectra;
- Planetary Evolution;
- Spectrum Analysis;
- Astrophysics