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 IUE Ultraviolet Spectrum of PC 11

1993 ◽  
Vol 155 ◽  
pp. 398-398 ◽  
Author(s):  
M. Parthasarathy ◽  
S.R. Pottasch ◽  
J. Clavel
Keyword(s):  
Short Wavelength ◽  
Planetary Nebula ◽  
Significant Variation ◽  
Central Star ◽  
Ultraviolet Spectrum ◽  
Emission Lines ◽  
Symbiotic Star ◽  
Iras Source ◽  
Long Wavelength ◽  
Cold Dust

PC 11 (HD 149427, PK 331-5 1) is classified as a young planetary nebula with strong OIII 4363Å and a Zanstra temperature of TZ = 27000K. It is also classified as (D′ — type) yellow symbiotic star with A — F type companion. It is an IRAS source with detached cold dust with far intrared (IRAS) colours similar to planetary nebulae. The IUE short wavelength (SWP) spectra show emission lines due to OIII] (1661/1666Å). NIII] (1746/1754Å) CIII] (1907/1909Å). The OIII] and NIII] emission lines show significant variation. Variation in the strength of CIII] is not very significant. The strength of OIII] has decreased and NIII] has increased. The long wavelength (LWP) spectrum shows stellar continuum (A-F) and absorption lines due Mg II 2800Å feature. It also show emission lines at 2772Å (?) 3133Å −3140Å (very strong) (OIII, [FeV], 3209Å (He II?) ([FEII]). The variation in the strength of emission line due OIII] and NIII] and the presence of stellar continuum (A-F) suggests that the central star of PC 11 is a binary.

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 Planetary Nebulae in the Magellanic Clouds

1978 ◽  
Vol 76 ◽  
pp. 11-18 ◽  
Author(s):  
B. Louise Webster
Keyword(s):  
Planetary Nebulae ◽  
Magellanic Clouds ◽  
Space Distribution ◽  
Helium Abundance ◽  
Selection Effects ◽  
High Excitation ◽  
Oxygen Abundance

Selection effects in the search for planetary nebulae in the Magellanic Clouds have not seriously distorted the observed space distribution, but have affected the apparent excitation classes. A difference between the properties of the SMC and LMC planetaries remains. A group of high-excitation nebulae with strong lines of He and N has been isolated. If these are excluded, the helium abundance appears to be normal in each Cloud. The oxygen abundance in LMC planetaries is about half the Orion value and may be even lower in the SMC objects. The significance of the abundances, excitation classes and space distribution is briefly discussed.

scholarly journals Helium abundances in planetary nebulae: Nucleosynthesis and chemical evolution

2009 ◽  
Vol 5 (S268) ◽  
pp. 181-182
Author(s):  
W. J. Maciel ◽  
R. D. D. Costa ◽  
T. E. P. Idiart
Keyword(s):  
Chemical Evolution ◽  
Planetary Nebulae ◽  
Magellanic Clouds ◽  
Heavy Elements ◽  
Solar Neighbourhood ◽  
Host Galaxies ◽  
Intermediate Mass ◽  
Large Sample ◽  
Intermediate Mass Stars ◽  
Progenitor Stars

AbstractWe have obtained a large sample of PN with accurately determined helium abundances, as well as abundances of several heavy elements. The nebulae are located in the solar neighbourhood, in the galactic bulge, disk and anticentre, and in the Magellanic Clouds. The abundances are analyzed both in terms of the nucleosynthesis of intermediate mass stars and the chemical evolution of the host galaxies. In particular, correlations between the He/H ratio and the abundances of N and O are used as constraints of the nucleosynthetic processes occurring in the progenitor stars.

scholarly journals The Radial Velocities of Planetary Nebulae in NGC 3379

1993 ◽  
Vol 155 ◽  
pp. 570-570
Author(s):  
Robin Ciardullo ◽  
George Jacoby
Keyword(s):  
Radial Velocity ◽  
Absorption Line ◽  
Planetary Nebula ◽  
Velocity Dispersion ◽  
Planetary Nebulae ◽  
Elliptical Galaxies ◽  
Emission Lines ◽  
Surface Photometry ◽  
Stellar Kinematics ◽  
Velocity Measurements

Several authors have analyzed the kinematics of elliptical galaxies using surface photometry in combination with absorption line velocity dispersion measurements. However, these analyses never explore the halos of galaxies, since the best absorption line measurements extend only ∼1 re. The only way to extend our knowledge of stellar kinematics to larger radii is to use the emission lines of planetary nebula for radial velocity measurements.

scholarly journals Evolution of Magellanic Cloud Planetary Nebulae

1989 ◽  
Vol 131 ◽  
pp. 356-356
Author(s):  
Stephen J. Meatheringham ◽  
Michael A. Dopita ◽  
Peter R. Wood ◽  
B. Louise Webster ◽  
David H. Morgan ◽  
...  
Keyword(s):  
Total Energy ◽  
Density Gradient ◽  
Planetary Nebula ◽  
Planetary Nebulae ◽  
Magellanic Cloud ◽  
Magellanic Clouds ◽  
Asymptotic Giant Branch ◽  
Expansion Velocity ◽  
Low Velocity ◽  
Tight Correlation

New evolutionary correlations have been discovered to apply to the population of Planetary Nebulae (FN) in the Magellanic Clouds. Firstly, the age of the nebular shell is found to follow a relationship τ = 890[(Mneb/M⊙) (Vexp/km s−1)]0,6 yr, which is shown to be consistent with a model in which the total energy of the ionised and swept up gas drives the expansion down the density gradient in the precursor AGE wind. Secondly, a tight correlation is found between the expansion velocity and a combination of the Excitation Class and the Hβ flux. This appears to be determined by the mass of the planetary nebula nuclear star. These correlations provide strong observational support for the idea that the PN shells are ejected at low velocity during the Asymptotic Giant Branch phase of evolution, and that they are continually accelerated during their nebular lifetimes.

scholarly journals Stellar Mixing from Galactic and Magellanic Cloud Planetary Nebulae Abundances

1991 ◽  
Vol 145 ◽  
pp. 387-397
Author(s):  
R. E. S. Clegg
Keyword(s):  
Main Sequence ◽  
Galactic Disk ◽  
Planetary Nebulae ◽  
Central Star ◽  
Magellanic Clouds ◽  
Large Scatter ◽  
Angular Momenta ◽  
Red Giant ◽  
Cno Abundances ◽  
Progenitor Stars

The mixing and nucleosynthetic processes which occur in the main-sequence and red giant stages of evolution and which can affect measured PN abundances are discussed. It is suggested that samples of planetary nebulae contain a sufficient range of progenitor stars' initial metallicities, angular momenta, binarity, etc. so as to explain the large scatter always seen in abundance diagrams for PN samples. CNO abundances in the Galactic disk and in the Magellanic Clouds are reviewed. New results for nebular abundances and central star properties in the Clouds are given. The current red giant population in the Clouds mix out more 12C per star than their Galactic disk counterparts.

scholarly journals Neon, sulphur, and argon abundances of planetary nebulae in the sub-solar metallicity Galactic anti-centre

2018 ◽  
Vol 615 ◽  
pp. A29 ◽  
Author(s):  
G. J. S. Pagomenos ◽  
J. Bernard-Salas ◽  
S. R. Pottasch
Keyword(s):  
Planetary Nebula ◽  
Milky Way ◽  
Planetary Nebulae ◽  
Ionic Species ◽  
Infrared Emission ◽  
Emission Lines ◽  
Solar Neighbourhood ◽  
Radial Dependence ◽  
Galactic Centre ◽  
H Ii Regions

Context. Spectra of planetary nebulae show numerous fine structure emission lines from ionic species, enabling us to study the overall abundances of the nebular material that is ejected into the interstellar medium. The abundances derived from planetary nebula emission show the presence of a metallicity gradient within the disk of the Milky Way up to Galactocentric distances of ~10 kpc, which are consistent with findings from studies of different types of sources, including H II regions and young B-type stars. The radial dependence of these abundances further from the Galactic centre is in dispute. Aims. We aim to derive the abundances of neon, sulphur and argon from a sample of planetary nebulae towards the Galactic anti-centre, which represent the abundances of the clouds from which they were formed, as they remain unchanged throughout the course of stellar evolution. We then aim to compare these values with similarly analysed data from elsewhere in the Milky Way in order to observe whether the abundance gradient continues in the outskirts of our Galaxy. Methods. We have observed 23 planetary nebulae at Galactocentric distances of 8–21 kpc with Spitzer IRS. The abundances were calculated from infrared emission lines, for which we observed the main ionisation states of neon, sulphur, and argon, which are little affected by extinction and uncertainties in temperature measurements or fluctuations within the planetary nebula. We have complemented these observations with others from optical studies in the literature, in order to reduce or avoid the need for ionisation correction factors in abundance calculations. Results. The overall abundances of our sample of planetary nebulae in the Galactic anti-centre are lower than those in the solar neighbourhood. The abundances of neon, sulphur, and argon from these stars are consistent with a metallicity gradient from the solar neighbourhood up to Galactocentric distances of ~20 kpc, albeit with varying degrees of dispersion within the data.

scholarly journals Planetary Nebulae Symposium - Introductory Remarks

1978 ◽  
Vol 76 ◽  
pp. XIX-XXI
Author(s):  
Yervant Terzian
Keyword(s):  
Emission Line ◽  
Planetary Nebula ◽  
Planetary Nebulae ◽  
Emission Lines

It seems proper to start our Symposium from the very beginning. The oldest known discovery of a planetary nebula dates back to Messier who in 1764 catalogued the Dumbbell nebula, NGC 6853, as Messier 27. Only 100 years later Huggins discovered the emission line spectra of planetary nebulae and he pointed out that his discovery proves that these objects are not clusters of stars but are “enormous masses of luminous gas or vapor”. In 1887, a curious suggestion was made by Lockyer who thought that the nebulae were clusters of burning meteorites when he incorrectly identified three nebular emission lines with magnesium.

scholarly journals A Method of Determination of the Temperature of Nuclei of the Planetary Nebulae

1968 ◽  
Vol 34 ◽  
pp. 330-331
Author(s):  
G.S. Khromov
Keyword(s):  
Heavy Ions ◽  
Planetary Nebula ◽  
Planetary Nebulae ◽  
Independent Method ◽  
Heavy Elements ◽  
Color Temperature ◽  
High Excitation ◽  
Method Of Determination

I would like to make a few comments on the problem of the determination of the temperatures of nuclei of planetary nebulae.It can be shown that in a high-excitation planetary nebula two independent Strömgren zones of heavy elements can be found. The first is a He III zone; the second corresponds to a zone of the luminescence of Ne V forbidden lines and originates due to combined absorption by the heavy ions Ne IV, O V and N V. If so, a relatively independent method of the determination of the color temperature of nuclei can be suggested.

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