Planetary Nebulae of Type I Revisited

In this work we report new high quality spectroscopic data for a sample of PNe in the SMC, aiming to derive physical parameters and chemical abundances, in particular to settle the question concerning the oxygen discrepancy found for type I planetaries with respect to stars and HII regions.

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N/O Abundances in Planetary Nebulae from Far-Infrared Line Observations

Symposium - International Astronomical Union ◽

10.1017/s0074180900138252 ◽

1989 ◽

Vol 131 ◽

pp. 214-214

Author(s):

Harriet L. Dinerstein ◽

Michael W. Werner

Keyword(s):

Planetary Nebulae ◽

Far Infrared ◽

Optical Observations ◽

Type I ◽

Local Electron ◽

Extreme Type ◽

Order Of Magnitude ◽

Progenitor Stars ◽

Infrared Array ◽

Atomic Parameters

Measurements of the [O III] 52, 88 μm and [N III] 57 μm fine-structure emission lines have been obtained for nine planetary nebulae, using the facility far-infrared array spectrometer on NASA's Kuiper Airborne Observatory. The N++/O++ ratios determined from these observations range by more than an order of magnitude among the sample. Using recent improved values for the atomic parameters, we find that the N++/O++ ratios agree fairly well with values of N+/O+ determined from optical lines in the same objects. The highest N++/O++ values, found for the extreme “Type I” nebulae NGC 2440 and NGC 6302, are approximately unity. These results imply that the synthesis and mixing of nitrogen must be extremely efficient in the progenitor stars of some planetary nebulae, and that these nebulae are significant sources of nitrogen to the interstellar medium. The local electron densities derived from the intensity ratios of the two [O III] lines are generally lower than values in the literature determined from small-beam optical observations of other ions, such as [O II]. This effect can be understood in terms of the presence of clumpy structure in the nebula, since the far-infrared lines have fairly low critical densities for collisional de-excitation and therefore are preferentially emitted from low-density gas.

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Hubble Space Telescope Images of Four Magellanic Cloud Planetary Nebulae

Symposium - International Astronomical Union ◽

10.1017/s0074180900170755 ◽

1993 ◽

Vol 155 ◽

pp. 213-213

Author(s):

M. J. Barlow ◽

J. C. Blades ◽

S. Osmer ◽

Keyword(s):

Hubble Space Telescope ◽

Planetary Nebulae ◽

Circular Ring ◽

Uniform Structure ◽

Full Description ◽

Type I ◽

Space Telescope ◽

Ring Shape ◽

Faint Object ◽

Northern Edge

Using the Faint Object Camera on-board the Hubble Space Telescope, we have obtained images of four planetary nebulae in the Magellanic Clouds, namely N2 and N5 in the SMC and N66 and N201 in the LMC. Each nebula was imaged through narrow-band filters isolating [O III] λ5007 and Hβ, for a nominal exposure time of 1000 seconds in each filter. The f/96 optical chain of the FOC was used, yielding 512×512 0.022 arcsec square pixels. Considerable detail is evident on the raw images and after deconvolution using the Richardson-Lucy algorithm, structures as small as 0.06 arcsec are easily discernible. Figure 1 shows NS and EW intensity cross-cuts through the deconvolved [O III] λ5007 images of SMC N2 and SMC N5. SMC N2 is a slightly ellleptical ringlike nebula, with its greatest elongation in the EW direction. The peak-to-peak dimensions of the ring are 0.21×0.26 arcsec2. SMC N5 has a circular ring shape, with the [O III] λ5007 image showing a clearly defined, nearly uniform structure, apart from a bright patch at the northern edge. The peak-to-peak diameter of the ring is 0.26 arcsec and the ring itself is significantly narrower than that of SMC N2, with a width as small as 0.06 arcsec (FWHM) in some places. LMC N201 is very compact, with a FWHM of 0.21 arcsec in the Hβ image. The Type I PN LMC N66 is a multi-polar nebula, with the brightest part having an extent of about 2 arcsec. Its structure is extremely complex, with several bright knots and faint loops visible outside the two bright lobes. A full description of our results can be found in Blades et al., ApJ,398, L41–44.

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Planetary Nebulae in the SMC

Symposium - International Astronomical Union ◽

10.1017/s0074180900209881 ◽

2003 ◽

Vol 209 ◽

pp. 625-628 ◽

Cited By ~ 8

Author(s):

George H. Jacoby ◽

Orsola De Marco ◽

Robin Ciardullo

Keyword(s):

Planetary Nebula ◽

Luminosity Function ◽

Planetary Nebulae ◽

Type I ◽

Complete Survey ◽

New Feature

Using the ESO 2.2m telescope with the 8K x 8K mosaic CCD, we surveyed 2.8 square degrees (~1.6° x 1.7°) of the SMC to search for faint planetary nebulae (PN). In this region, 34 PN were previously known; we identified 25 new objects. All of these are faint and have been spectroscopically confirmed. We estimate that there should be ~140 PN in the entire SMC to the limits of a survey like this one, which is complete to 6 mag down the planetary nebula luminosity function (PNLF). For a complete survey (8 mag down the PNLF), there should be ~220 PN. A strong new feature is evident in the PNLF as a deficiency at 4 mags below the brightest PN.The survey spectra that were used to confirm the candidates as PN show that the fainter PN exhibit a higher incidence (~28%) of strong [N II] emission (where I([N II]/I(Hα) > 1) relative to the bright Sanduleak et al. (1978) sample (~6%). We propose that the very faint SMC PN are selectively biased toward the chemically enriched Type I objects derived from younger, more massive progenitors.

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Abundance Analysis of a Sample of Bipolar Type I Planetary Nebulae

10.1063/1.2146227 ◽

2005 ◽

Author(s):

O. Lorente-Espin

Keyword(s):

Planetary Nebulae ◽

Type I ◽

Bipolar Type

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The role of shocks in the determination of empirical abundances for type-I PNe

Proceedings of the International Astronomical Union ◽

10.1017/s1743921318003800 ◽

2018 ◽

Vol 14 (S343) ◽

pp. 377-378

Author(s):

Roberto D. D. Costa ◽

Paulo J. A. Lago

Keyword(s):

Planetary Nebulae ◽

Type I ◽

Correction Factors ◽

Chemical Abundances

AbstractWe investigate, in the light of new diagnostic diagrams, the role of shocks in the ionization profile of type-I planetary nebulae, and their relation to the empirical derivation of chemical abundances. We apply our technique to two well-known type-I objects: NGC 2440 and NGC 6302. Our results indicate that shocks play a very important role in the spectra of both nebulae and, since the presence of shocks reinforces the flux of low ionization lines, this artificial reinforcement can lead to incorrect chemical abundances, when they are derived through Ionization Correction Factors, at least for type-I PNe.

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Filling factor and temperature variations in planetary nebulae

Proceedings of the International Astronomical Union ◽

10.1017/s1743921312011969 ◽

2011 ◽

Vol 7 (S283) ◽

pp. 468-469

Author(s):

Manuel Peimbert ◽

Antonio Peimbert

Keyword(s):

Chemical Evolution ◽

Strong Correlation ◽

Filling Factor ◽

Planetary Nebulae ◽

Type I ◽

Type Ii ◽

Galactic Chemical Evolution ◽

Temperature Variations

AbstractWe have found a strong correlation between small filling factors and large t2 values in planetary nebulae. We have also found that in general the filling factor for Type I PNe is smaller than for Type II PNe. These results imply that the abundance correction due to temperature inhomogeneities in general is larger for Type I PNe than for Type II PNe. This difference permits to reproduce the expected abundance difference between PNe of Type I and II predicted by Galactic chemical evolution models.

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The case of NGC 6302: the impact of shocks in the derivation of nitrogen abundances

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz2319 ◽

2019 ◽

Vol 489 (2) ◽

pp. 2923-2929

Author(s):

P J A Lago ◽

R D D Costa ◽

M Faúndez-Abans ◽

W J Maciel

Keyword(s):

Emission Line ◽

Correction Factor ◽

Planetary Nebulae ◽

Type I ◽

Excitation Mechanism ◽

High Nitrogen ◽

Filamentary Structure ◽

Usual Assumption ◽

Nitrogen Abundance ◽

The Impact

ABSTRACT High nitrogen abundance is characteristic of Type I planetary nebulae, as well as their highly filamentary structure. In the present work, we test the hypothesis of shocks as a relevant excitation mechanism for a Type I nebula, NGC 6302, using recently released diagnostic diagrams to distinguish shocks from photoexcitation. The construction of the diagrams depends on emission-line ratios and kinematical information. NGC 6302 shows the relevance of shocks in peripheral regions and their importance to the whole nebula. Using shocks, we question the usual assumption of ionization correction factor calculation, justifying a warning regarding broadly used abundance derivation methods. From kinematical analysis, we derive a new distance for NGC 6302 of $805\pm 143\,$ pc.

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IFU Spectroscopy of Southern Planetary Nebulae V: Low-Ionisation Structures

Publications of the Astronomical Society of Australia ◽

10.1017/pasa.2017.30 ◽

2017 ◽

Vol 34 ◽

Cited By ~ 8

Author(s):

A. Ali ◽

M. A. Dopita

Keyword(s):

Emission Line ◽

Planetary Nebulae ◽

Central Star ◽

Chemical Compositions ◽

Physical Analysis ◽

Type I ◽

High Excitation ◽

Chemical Abundances ◽

Physical Conditions ◽

Integral Field Spectroscopy

AbstractIn this fifth paper of the series, we examine the spectroscopy and morphology of four southern Galactic planetary nebulae Hen 2-141, NGC 5307, IC 2553, and PB 6 using new integral field spectroscopy data. The morphologies and ionisation structures of the sample are given as a set of emission-line maps. In addition, the physical conditions, chemical compositions, and kinematical characteristics of these objects are derived. The results show that PB 6 and Hen 2-141 are of very high excitation classes and IC 2553 and NGC 5307 are mid to high excitation objects. The elemental abundances reveal that PB 6 is of Type I, Hen 2-141 and IC 2553 are of Type IIa, and NGC 5307 is of Type IIb/III. The observations unveil the presence of well-defined low-ionisation structures or ‘knots’ in all objects. The diagnostic diagrams reveal that the excitation mechanism of these knots is probably by photoionisation of dense material by the nebular central stars. The physical analysis of six of these knots show no significant differences with their surrounding nebular gas, except their lower electron densities. In spite of the enhancement of the low-ionisation emission lines of these knots, their chemical abundances are nearly comparable to their surrounding nebulae, with the exception of perhaps slightly higher nitrogen abundances in the NGC 5307 knots. The integrated spectrum of IC 2553 reveals that nearly all key lines that have led researchers to characterise its central star as a weak-emission line star type are in fact of nebular origin.

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