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 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 Physical parameters and chemical abundances of Planetary Nebulae in the large Magellanic Cloud

1997 ◽  
Vol 180 ◽  
pp. 471-471 ◽  
Author(s):  
R. E. Carlos Reyes ◽  
J. E. Steiner ◽  
F. Elizalde
Keyword(s):  
Planetary Nebulae ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Physical Parameters ◽  
Chemical Abundances ◽  
The Difference

In the present work we have computed the physical parameters and chemical abundances for 45 planetary nebulae (PN) in the Large Magellanic Cloud (LMC) using the photoionization code CLOUDY, developed by Ferland (1993). CLOUDY is used as a subroutine in the code DIANA, developed by Elizalde & Steiner (1996), which minimises indices that measures the difference between the calculated and real nebula.

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 Chemical abundances in planetary nebulae in three different galaxies

2009 ◽  
Vol 5 (S265) ◽  
pp. 155-158
Author(s):  
Miriam Peña
Keyword(s):  
Strong Evidence ◽  
Preliminary Analysis ◽  
Planetary Nebulae ◽  
Hii Regions ◽  
Young Population ◽  
Chemical Behavior ◽  
Galactocentric Distance ◽  
Chemical Abundances ◽  
Low Metallicity ◽  
Ngc 6822

AbstractWe analyze the PNe chemical behavior in three different galaxies, two dwarf irregulars and one spiral. Different behaviors are found. In the very low metallicity galaxy NGC 3109, PNe analyzed appear 0.39 dex O-richer than HII regions, while Ar/H ratio is, in average, 0.15 dex poorer. We interpret this as an evidence of significant O dredge-up in these LIMS, born in a very low metallicity environment. In NGC 6822, with a present metallicity 12+log O/H=8.06, two PN populations were found. A young one, with abundances similar to those in HII regions and an old population, with metallicities a factor of two lower. In this case no strong evidence for O dredge-up in LIMS is found. Therefore, metallicities lower than 12+log O/H =7.7 are required for an efficient O dredge-up. From our preliminary analysis of the abundances of PNe in NGC 300 we find that they are similar to the abundances in HII regions. Apparently, the PNe analyzed belong to a young population. Very similar abundance gradients, with galactocentric distance, are found for HII regions and for PNe.

scholarly journals Chemical Abundances of Planetary Nebulae in the LMC

1993 ◽  
Vol 155 ◽  
pp. 586-586
Author(s):  
J.A. De Freitas Pacheco ◽  
R.D.D. Costa
Keyword(s):  
Electron Temperature ◽  
Chemical Evolution ◽  
Spectroscopic Data ◽  
National Laboratory ◽  
Planetary Nebulae ◽  
Chemical Abundances ◽  
Ccd Detector ◽  
Progenitor Stars

We report new spectroscopic data on a sample constituted of 21 well observed planetary nebulae in the LMC. The observations were performed at the National Laboratory for Astrophysics (Brazópolis — Brasil) using the 1.6m telescope and a CCD detector. Extinction, electron temperature and densities were derived for all the planetaries and a comparison is made with results obtained by other surveys, including common objects. Chemical abundances of helium, nitrogen, oxygen, sulphur and argon were also derived for all sample objects. Enrichment of the progenitor stars in He and N due to mixing episodes as well as the relation with the chemical evolution of the LMC are discussed in terms of our data and other observations.

scholarly journals The population of planetary nebulae near the Galactic Centre: chemical abundances

2016 ◽  
Vol 12 (S323) ◽  
pp. 339-340
Author(s):  
M. Mollá ◽  
O. Cavichia ◽  
R. D. D. Costa ◽  
W. J. Maciel
Keyword(s):  
Luminosity Function ◽  
Planetary Nebulae ◽  
Galactic Centre ◽  
Physical Parameters ◽  
Chemical Compositions ◽  
Galactic Bulge ◽  
Chemical Abundances ◽  
Chemical Enrichment ◽  
History Of ◽  
Low Dispersion

AbstractIn this work, we report physical parameters and abundances derived for a sample of 15 high extinction planetary nebulae located in the inner 2° of the Galactic bulge, based on low dispersion spectroscopy secured at the SOAR telescope using the Goodman spectrograph. The new data allow us to extend our database including older, weaker objects that are at the faint end of the planetary nebulae luminosity function. The data provide chemical compositions for PNe located in this region of the bulge to explore the chemical enrichment history of the central region of the Galactic bulge. The results show that the abundances of our sample are skewed to higher metallicities than previous data in the outer regions of the bulge. This can indicate a faster chemical enrichment taking place at the Galactic centre.

scholarly journals Emission Lines of Northern Planetary Nebulae

2016 ◽  
Vol 12 (S323) ◽  
pp. 333-334
Author(s):  
Nazim Aksaker ◽  
Sinan K. Yerli ◽  
Ümit Kızıloğlu ◽  
Betül Atalay
Keyword(s):  
Emission Line ◽  
Supernova Remnants ◽  
Planetary Nebulae ◽  
Hii Regions ◽  
Emission Lines ◽  
Line Flux ◽  
Chemical Abundances ◽  
Data Set ◽  
Standard Data ◽  
Spectrometric Measurements

AbstractIn this work, we present results of long slit spectrophotometric emission line flux observations of selected planetary nebulae (PNe). We have measured absolute fluxes and equivalent widths (EW) of all observable emission lines. In addition to these observations, electron temperatures (Te), densities (Ne), and chemical abundances were also calculated. The main purpose of this work is to fill the gaps in emission line flux standards for the northern hemisphere. It is expected that the measured fluxes would be used as standard data set for further photometric and spectrometric measurements of HII regions, supernova remnants etc.

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 from Planetary Nebulae in Elliptical Galaxies

1995 ◽  
Vol 10 ◽  
pp. 483-485
Author(s):  
J.R. Walsh
Keyword(s):  
Local Group ◽  
Elliptical Galaxy ◽  
Planetary Nebulae ◽  
Elliptical Galaxies ◽  
Line Flux ◽  
Chemical Abundances ◽  
High Quality ◽  
Ccd Photometry ◽  
S0 Galaxies

Currently over 2000 Planetary Nebulae (PN) have been detected in Local Group E and S0 galaxies by on/off band [O III]5007Å CCD photometry. PN can currently be detected out to Fornax and Virgo clusters.The magnitude of the brightest PN in the nearest elliptical galaxy (NGC 205) is m5007 20.7 (Ciardullo et al, 1989); for NGC 5128 (Cen-A) it is 23.5 (Hui et al, 1993a) and ≥ 25.6 for Virgo ellipticals (Jacoby et al, 1990). Given the relation between m5007 and line flux:m5007 = −2.5 log F5007 − 13.74the typical Hβ fluxes are ≤1.5×10-16 ergs cm−2 s−1 for NGC 5128 PN and ≤ 2.5×10−17 for Virgo PN. Obtaining spectra of these faint emisison lines is clearly a challenge. The only PN spectra studied in Local Group galaxies are 1 PN in M32 (NGC 221) (Log F(H/β) = −14.9; Jenner et al, 1979) and recently 15 in NGC 205 (Jacoby et al, 1995). None of the spectra are of high quality and the Te diagnostic line [O III]4363Å was not detected. There is evidence of possible high N abundance in the M32 PN.

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