Astron. J., 125, 265-271 (2003/January-0)
Observations of [S IV] 10.5 µm and [Ne II] 12.8 µm in two halo planetary nebulae: implications for chemical self-enrichment.
DINERSTEIN H.L., RICHTER M.J., LACY J.H. and SELLGREN K.
Abstract (from CDS):
We have detected the [S IV] 10.5 µm and [Ne II] 12.8 µm fine-structure lines in the halo population planetary nebula (PN) DdDm 1 and set upper limits on their intensities in the halo PN H4-1. We also present new measurements of optical lines from various ions of S, Ne, O, and H for DdDm 1, based on a high-dispersion spectrum covering the spectral range 3800 Å to 1 µm. These nebulae have similar O/H abundances, (O/H)∼1x10–4, but S/H and Ne/H are about half an order of magnitude lower in H4-1 than in DdDm 1; thus H4-1 appears to belong to a more metal-poor population. This supports previous suggestions that PNe arising from metal-poor progenitor stars can have elevated oxygen abundances due to internal nucleosynthesis and convective dredge-up. It is generally accepted that high abundances of carbon in many PNe result from self-enrichment. To the extent that oxygen can also be affected, the use of nebular O/H values to infer the overall metallicity of a parent stellar population (for example, in external galaxies) may be suspect, particularly for low metallicities.
Infrared Radiation - ISM: Planetary Nebulae: General - planetary nebulae: individual (DdDm 1, H4-1) - Stars: AGB and Post-AGB
In conclusion, PRGM is a misprint for PRMG (PN PRMG 1)
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