Elemental Abundances in Planetary Nebulae

Kaler, J. B.

doi:10.1007/978-94-009-7094-6_26

Cited by 20 publications

(16 citation statements)

References 60 publications

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“…0 3+ /(0 + +0 2+ ) was calculated from the He 2+ /He + ratio, N/O was set equal to N + /0 + (and set into parentheses in the cases wherein 0 + /H + was derived from [O i] X6300). Approximate C/O ratios were derived from C il X4267 and Kaler's (1983) algorithm. The Ne +2 /0 ratios in the last column provide a useful check.…”

Section: Resultsmentioning

confidence: 99%

Spectrophotometry of Planetary Nebulae. III. IIDS Observations of Compact Nebulae

Kaler¹,

Kwitter²,

Shaw³

et al. 1996

PASP

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We give spectral line intensities, electron temperatures, electron densities, and chemical compositions for 25 compact planetary nebulae observed with the IIDS at Kitt Peak. Several (Ha 3-75, He 2-15, K 3-89, M 1-16, M 2-52, and M 3-28) are found to be especially rich in helium and/or nitrogen (He/H>0.15; N/0>1). The results minimally confirm the correlation between N/O and He/H, but also confirm the intrinsic scatter in the relation, as N-rich nebulae can be unenriched in He and vice versa.

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Section: Resultsmentioning

confidence: 99%

Spectrophotometry of Planetary Nebulae. III. IIDS Observations of Compact Nebulae

Kaler¹,

Kwitter²,

Shaw³

et al. 1996

PASP

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“…The molecular weight /z is taken ~1 (gas only composed of neutral hydrogen). This latter hypothesis may not be very realistic because the matter is likely enriched by heavier elements during the dredge-up processes (Kaler 1983) or the toroidlike bubble uplift (Pascoli 1990c(Pascoli , 1991. Moreover, when T is lower than 500 K, molecule formation will be important for H 2 , CO, and dust.…”

Section: The Mhd Equations Of the Modelmentioning

confidence: 99%

On the shaping of circumstellar envelopes

Pascoli¹,

Leclercq²,

Poulain³

1992

PASP

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ABSTRACT. In this paper, we examine the evolutionary process of expansion of a magnetized ring of cool matter ejected from a red giant. The subsequent formation of a circumstellar shell or preplanetary nebula is also analyzed. The velocity, density, and magnetic field are calculated along a time sequence, on a large two-dimensional grid of points close to and far away from the star. Owing to long-range forces such as thermal pressure gradients and magnetic stresses, the velocity field becomes a linear function of the distance. The latitudinal dependence of this function is poor, while conversely the density distribution is clearly aspheric. The magnetic field intensity at a distance -10 15 -10 16 cm is in good agreement with the observational data. The isophotes are plotted and compared to observational contours obtained from the literature. The filamentary structure appearance and its stability within the envelope are also discussed.

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“…(3) We assume Ne/O = 0.25, a value typical of PNe (Aller and Czyzak 1983) and from this deduce the oxygen abundance. Likewise, we assume Ar/O = 7 X 10 -3 (Kaler 1978), i.e., Ar/Ne = 0.028, and deduce the argon abundance from this. (4) For carbon and nitrogen, we take C/O = C +2 /0 +2 and N/O = N +3 /0 +3 .…”

Section: Abundancesmentioning

confidence: 99%

Utraviolet observations of the planetary nebula NGC 2242

Garnett¹,

Dinerstein²

1989

PASP

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We present IUE observations of the high-ionization planetary nebula NGC 2242. The ultraviolet spectrum exhibits strong emission lines of C IV, He il, C III], and [Ne iv], plus weaker emission from O IV and N IV. We have also obtained narrow-band imaging of NGC 2242 in the He II 4686 Â emission line; comparison of the \4686 flux from this image with the \1640 flux from the UV spectrum gives a reddening coefficient c(Hß) = 0.37, consistent with that derived from our optical spectrum. From the UV data and previously published optical spectra, we estimate abundances for He, C, O, Ne, and Ar. The oxygen abundance is approximately one-sixth the solar value for T e = 25,000 K; Ne/H and Ar/H are down by a factor of two to three from typical disk PN values. C/O is probably not greater than unity. Helium is not enhanced, arguing against classification as a Type I PN. The observed abundance pattern in NGC 2242 resembles that seen in the halo planetary DDDM-1, except for the strikingly low C/O ratio in the latter object. We suggest that a proper-motion study be done to determine whether NGC 2242 is a member of the disk or of the halo population.

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Elemental Abundances in Planetary Nebulae

Cited by 20 publications

References 60 publications

Spectrophotometry of Planetary Nebulae. III. IIDS Observations of Compact Nebulae

Spectrophotometry of Planetary Nebulae. III. IIDS Observations of Compact Nebulae

On the shaping of circumstellar envelopes

Utraviolet observations of the planetary nebula NGC 2242

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