Spectrum of the high-excitation planetary Nebula NGC 6741 (33-2 deg 1)

1985 ◽  
Vol 296 ◽  
pp. 492 ◽  
Author(s):  
L. H. Aller ◽  
C. D. Keyes ◽  
S. J. Czyzak
Keyword(s):  
Planetary Nebula ◽  
High Excitation

The High‐Excitation Planetary Nebula NGC 7662

1997 ◽  
Vol 491 (1) ◽  
pp. 242-253 ◽  
Author(s):  
Siek Hyung ◽  
Lawrence H. Aller
Keyword(s):  
Planetary Nebula ◽  
High Excitation ◽  
Ngc 7662

scholarly journals Models of Planetary Nebulae: Generalisation of the Multiple Winds Model

1989 ◽  
Vol 131 ◽  
pp. 411-424 ◽  
Author(s):  
F. D. Kahn
Keyword(s):  
Planetary Nebula ◽  
High Speed ◽  
Planetary Nebulae ◽  
Central Star ◽  
Theoretical Description ◽  
Basic Theory ◽  
Spectral Lines ◽  
High Excitation ◽  
General Shape ◽  
Fast Wind

According to the multiple winds model a planetary nebula forms as the result of the interaction of a fast wind from the central star with the superwind that had previously been emitted by the progenitor star. The basic theory which deals with the spherically symmetrical case is briefly summarised. Various improvements are then considered in turn. A better history is clearly needed of the way that the central star becomes hotter, it is unrealistic to make the assumption that the superwind is spherically symmetrical, and finally there are likely to be important instabilities at some of the interfaces in the PN, notably that between the shocked superwind and the HII layer. These changes in the theoretical description produce a better understanding of the conditions in the outer parts of a PN and of the nature of its general shape, and they should lead to an explanation for the occurrence of high speed motions, and of highly ionized species and high excitation spectral lines.

scholarly journals N 66: A High Excitation N Rich Planetary Nebula in the LMC

1989 ◽  
Vol 131 ◽  
pp. 353-353
Author(s):  
M. Peña ◽  
M. T. Ruiz
Keyword(s):  
Spectral Range ◽  
Planetary Nebula ◽  
High Excitation

Spectrophotometry data of the planetary nebula N 66 (WS 35) has been obtained with the CTIO 4-m telescope equipped with an R-C spectrograph and a 2D-Frutti detector. The spectral range between 3700 A and 6800 A was covered at 4 A resolution.

scholarly journals Spectroscopy of Extragalactic Planetary Nebulae in the Ultraviolet

1983 ◽  
Vol 103 ◽  
pp. 545-545
Author(s):  
T.R. Gull ◽  
S.P. Maran ◽  
T.P. Stecher ◽  
L. H. Aller
Keyword(s):  
Planetary Nebula ◽  
Planetary Nebulae ◽  
Magellanic Clouds ◽  
Emission Lines ◽  
High Excitation ◽  
Long Wavelength ◽  
International Ultraviolet Explorer ◽  
Interstellar Media ◽  
Progenitor Stars ◽  
Stellar Envelopes

Three high-excitation planetary nebulae in the Magellanic Clouds were successfully observed with the International Ultraviolet Explorer. Emission lines as well as nebular and stellar continua were detected. Fluxes in the lines 1550 C IV, 1640 He II, 1663 O III, and 1909 C III were measured in spectra of LMC P40, SMC N2, and SMC N5 obtained with the IUE short wavelength spectrograph; 2422 Ne IV was measured in P40 with the long wavelength spectrograph. The data were analyzed together with groundbased observations by Aller in order to derive ionization models and the nebular abundances of He, C, N, O, S, Ar. The C abundances are as large as those typically found in galactic planetaries, although the interstellar media of the Clouds are notably deficient in C. Thus, the C was synthesized in the progenitor stars and presumably was lifted to the stellar envelopes by convection prior to the ejection of the nebulae. Other planetary nebulae in the Clouds, as well as the planetary nebula in the Fornax galaxy, may be observable with IUE.

scholarly journals The Hubble-Type Outflows from the High-Excitation, Polypolar Planetary Nebula NGC 6302

2005 ◽  
Vol 130 (5) ◽  
pp. 2303-2311 ◽  
Author(s):  
J. Meaburn ◽  
J. A. López ◽  
W. Steffen ◽  
M. F. Graham ◽  
A. J. Holloway
Keyword(s):  
Planetary Nebula ◽  
High Excitation

scholarly journals Photoionization Models of the Eskimo Nebula: Evidence for a Binary Central Star?

2011 ◽  
Vol 7 (S282) ◽  
pp. 470-471
Author(s):  
A. Danehkar ◽  
D. J. Frew ◽  
Q. A. Parker ◽  
O. De Marco
Keyword(s):  
White Dwarf ◽  
Planetary Nebula ◽  
Central Star ◽  
Close Binary ◽  
High Excitation ◽  
Type Ia Supernova ◽  
Type Ia ◽  
Hubble Time

AbstractThe ionizing star of the planetary nebula NGC 2392 is too cool to explain the high excitation of the nebular shell, and an additional ionizing source is necessary. We use photoionization modeling to estimate the temperature and luminosity of the putative companion. Our results show it is likely to be a very hot (Teff ≃ 250 kK), dense white dwarf. If the stars form a close binary, they may merge within a Hubble time, possibly producing a Type Ia supernova.

The Complex Environment of the High‐Excitation Planetary Nebula NGC 3242

2000 ◽  
Vol 128 (1) ◽  
pp. 321-334 ◽  
Author(s):  
J. Meaburn ◽  
J. A. Lopez ◽  
A. Noriega‐Crespo
Keyword(s):  
Planetary Nebula ◽  
High Excitation ◽  
Complex Environment

scholarly journals Planetary nebulae with Wolf–Rayet-type central stars – I. The case of the high-excitation NGC 2371

2020 ◽  
Vol 496 (1) ◽  
pp. 959-973
Author(s):  
V M A Gómez-González ◽  
J A Toalá ◽  
M A Guerrero ◽  
H Todt ◽  
L Sabin ◽  
...  
Keyword(s):  
Stellar Evolution ◽  
Planetary Nebula ◽  
Symmetry Axis ◽  
High Excitation ◽  
Central Cavity ◽  
Isaac Newton ◽  
Double Structure ◽  
High Ionization ◽  
Isaac Newton Telescope ◽  
Central Stars

ABSTRACT We present the analysis of the planetary nebula (PN) NGC 2371 around the [Wolf–Rayet] (WR) star WD 0722+295. Our Isaac Newton Telescope intermediate dispersion spectrograph spectra, in conjunction with archival optical and ultraviolet images, unveil in unprecedented detail the high ionization of NGC 2371. The nebula has an apparent multipolar morphology, with two pairs of lobes protruding from a barrel-like central cavity, a pair of dense low ionization knots misaligned with the symmetry axis embedded within the central cavity, and a high-excitation halo mainly detected in He ii. The abundances from the barrel-like central cavity and dense knots agree with abundance determinations for other PNe with [WR]-type central stars of PNe. We suggest that the densest knots inside NGC 2371 are the oldest structures, remnant of a dense equatorial structure, while the main nebular shell and outer lobes resulted from a latter ejection that ended the stellar evolution. The analysis of position–velocity diagrams produced from our high-quality spectra suggests that NGC 2371 has a bipolar shape with each lobe presenting a double structure protruding from a barrel-like central region. The analysis of the spectra of WD 0722+295 results in similar stellar parameters as previously reported. We corroborate that the spectral subtype corresponds with a [WO1] type.

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