Spectrophotometry of Selected Planetary Nebulae of Type I in the Magellanic Clouds

1993 ◽  
Vol 155 ◽  
pp. 584-584 ◽  
Author(s):  
S. Torres-Peimbert ◽  
M. Peimbert ◽  
M.T. Ruitz ◽  
M. Peña
Keyword(s):  
Wavelength Range ◽  
Planetary Nebulae ◽  
Magellanic Clouds ◽  
Type I ◽  
Chemical Abundances ◽  
Spectroscopic Observations ◽  
Physical Conditions

We carried out spectroscopic observations of N67 (in the SMC), and N66, N97 and N102 (in the LMC) with the 4-m telescope of CTIO. The wavelength range is λλ 3500–7400. From these we obtained physical conditions and chemical abundances of these objects.

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

2017 ◽  
Vol 34 ◽  
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.

scholarly journals Chemical Abundances in Magellanic Cloud Planetary Nebulae

1989 ◽  
Vol 131 ◽  
pp. 354-354
Author(s):  
D. J. Monk ◽  
M. J. Barlow ◽  
R. E. S. Clegg
Keyword(s):  
Spectroscopic Data ◽  
Planetary Nebulae ◽  
Magellanic Cloud ◽  
Magellanic Clouds ◽  
Type I ◽  
Chemical Abundances ◽  
Special Groups

Optical spectroscopic data for 71 Planetary Nebulae (PN) in the Large and Small Magellanic Clouds have been analysed. The line fluxes have been used to determine nebular temperatures, densities, and the abundances of He, N, O, Ne and Ar, relative to H. In our sample there are 12 nebulae with N/O ≥ 0.5, resembling Peimbert's Type I PN; 6 low excitation (LE) objects (1 ≤ I(5007)/I(Hβ) ≤ 4); and 4 very-low-excitation (VLE) nebulae (I(Hβ) > I(5007), similar to the Galactic VLE class. Mean abundances have been calculated for the nebulae not in these special groups.

scholarly journals Twenty years of observations of PM 1-188: Its chemical abundances and extraordinary kinematics

2021 ◽  
Author(s):  
Miriam Peña ◽  
Liliana Hernández-Martínez ◽  
Francisco Ruiz-Escobedo
Keyword(s):  
Chemical Composition ◽  
Planetary Nebula ◽  
Central Star ◽  
Emission Lines ◽  
Type I ◽  
Chemical Abundances ◽  
Line Intensities ◽  
Physical Conditions ◽  
The Past ◽  
Spectrophotometric Data

Abstract The analysis of 20 years of spectrophotometric data of the double shell planetary nebula PM 1-188 is presented, aiming to determine the time evolution of the emission lines and the physical conditions of the nebula, as a consequence of the systematic fading of its [WC 10] central star whose brightness has declined by about 10 mag in the past 40 years. Our main results include that the [O iii], [O ii], [N ii] line intensities are increasing with time in the inner nebula as a consequence of an increase in electron temperature from 11 000 K in 2005 to more than 14 000 K in 2018, due to shocks. The intensity of the same lines are decreasing in the outer nebula, due to a decrease in temperature, from 13 000 K to 7000 K, in the same period. The chemical composition of the inner and outer shells was derived and they are similar. Both nebulae present subsolar O, S and Ar abundances, while they are He, N and Ne rich. For the outer nebula the values are 12+log He/H = 11.13 ± 0.05, 12+log O/H = 8.04 ± 0.04, 12+log N/H = 7.87 ± 0.06, 12+log S/H = 7.18 ± 0.10 and 12+log Ar = 5.33 ± 0.16. The O, S and Ar abundances are several times lower than the average values found in disc non-Type I PNe, and are reminiscent of some halo PNe. From high resolution spectra, an outflow in the N-S direction was found in the inner zone. Position-velocity diagrams show that the outflow expands at velocities in the −150 to 100 km s−1 range, and both shells have expansion velocities of about 40 km s−1.

Spectrophotometry of Selected Planetary Nebulae of Type I in the Magellanic Clouds

1993 ◽  
pp. 584-584
Author(s):  
S. Torres-Peimbert ◽  
M. Peimbert ◽  
M. T. Ruitz ◽  
M. Peña
Keyword(s):  
Planetary Nebulae ◽  
Magellanic Clouds ◽  
Type I

scholarly journals Helium and Oxygen Abundances in SMC Planetary Nebulae

2000 ◽  
Vol 198 ◽  
pp. 234-235
Author(s):  
R. D. D. Costa ◽  
J. A. de Freitas Pacheco ◽  
T. P. Idiart
Keyword(s):  
Spectroscopic Data ◽  
Planetary Nebulae ◽  
Hii Regions ◽  
Physical Parameters ◽  
Type I ◽  
Chemical Abundances ◽  
High Quality

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.

scholarly journals Spectroscopic Observations of Planetary Nebulae in the Magellanic Clouds

1968 ◽  
Vol 34 ◽  
pp. 34-35 ◽  
Author(s):  
M. W. Feast
Keyword(s):  
Planetary Nebulae ◽  
Magellanic Clouds ◽  
Preliminary Results ◽  
Spectroscopic Observations

A programme of spectroscopic observations of planetary nebulae in both Magellanic Clouds has been underway in Pretoria for some years, and some preliminary results for the LMC have been published (Feast, 1964b). More extensive observations are now available (altogether in both clouds 112 spectra of 39 objects), and these are being prepared for publication elsewhere. Below are summarized the main conclusions so far deduced.

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

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.

scholarly journals The impact of spectra quality on nebular abundances

2020 ◽  
Vol 495 (1) ◽  
pp. 1016-1034 ◽  
Author(s):  
Mónica Rodríguez
Keyword(s):  
Planetary Nebulae ◽  
The Other ◽  
Statistical Equilibrium ◽  
Emission Lines ◽  
Reference Spectrum ◽  
Equilibrium Equations ◽  
Chemical Abundances ◽  
Physical Conditions ◽  
Observational Errors ◽  
The Impact

ABSTRACT I explore the effects of observational errors on nebular chemical abundances using a sample of 179 optical spectra of 42 planetary nebulae (PNe) observed by different authors. The spectra are analysed in a homogeneous way to derive physical conditions and ionic and total abundances. The effects of recombination on the [O ii] and [N ii] emission lines are estimated by including the effective recombination coefficients in the statistical equilibrium equations that are solved for O+ and N+. The results are shown to be significantly different than those derived using previous approaches. The O+ abundances derived with the blue and red lines of [O ii] differ by up to a factor of 6, indicating that the relative intensities of lines widely separated in wavelength can be highly uncertain. In fact, the He ii lines in the range 4000–6800 Å imply that most of the spectra are bluer than expected. Scores are assigned to the spectra using different criteria and the spectrum with the highest score for each PN is taken as the reference spectrum. The differences between the abundances derived with the reference spectrum and those derived with the other spectra available for each object are used to estimate the 1σ observational uncertainties in the final abundances: 0.11 dex for O/H and Ar/H, 0.14 dex for N/H, Ne/H, and Cl/H, and 0.16 dex for S/H.

scholarly journals Abundances in Magellanic Cloud planetary nebulae

1991 ◽  
Vol 148 ◽  
pp. 291-298 ◽  
Author(s):  
M. J. Barlow
Keyword(s):  
Planetary Nebulae ◽  
Magellanic Cloud ◽  
Magellanic Clouds ◽  
Type I ◽  
The Third

The enhanced nitrogen abundances in planetary nebulae (PN) show the effects of CN-cycle processing at the time of the first dredge-up, while their very enhanced carbon abundances show the effects of the third dredge-up. The efficiency of both the first and third dredge-ups increases with decreasing initial metallicity. ON-cycle depletion of oxygen via the second dredge-up does not appear to have been significant in LMC Type I planetary nebulae (those with N/O > 0.5) – these nebulae have experienced the third dredge-up and envelope-burning, giving enhanced C+N abundances. The LMC Type I PN show enhanced Ne/O ratios. Enrichment rates in nitrogen and carbon by PN are estimated for the ISM s of the Magellanic Clouds.

scholarly journals Chemical Abundances from Planetary Nebulae in the Magellanic Clouds

1995 ◽  
Vol 10 ◽  
pp. 476-479 ◽  
Author(s):  
M.J. Barlow
Keyword(s):  
Electron Temperature ◽  
Heavy Element ◽  
Planetary Nebulae ◽  
Density Fluctuations ◽  
Magellanic Cloud ◽  
Magellanic Clouds ◽  
Chemical Abundances ◽  
Element Abundances

AbstractHeavy element abundances, in particular those of oxygen, obtained from recent spectroscopic surveys of Magellanic Cloud planetary nebulae (PN), are reviewed and compared with those derived for H regions and objects in our own galaxy. These abundances have been based on collisionally excited lines and are very sensitive to the adopted electron temperature. There is increasing evidence that temperature or density fluctuations within nebulae lead to the electron temperatures being overestimated, with the corollary that the heavy element abundances have been underestimated.

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