Results 161 to 170 of about 335 (184)

The temperatures of the nuclei of high-excitation planetary nebulae

Astrophysics and Space Science, 1988
An empirical relationship between the ratio of the intensities of emission lines in spectra of planetary nebulae, 4686 Heii/Hβ andN1+N2[Oiii]/4868 Heii, is established (see Equation (1), curve in Figure 1). A new statistical temperature scale based on this empirical relationship is proposed for the determination of lower limits of the temperatures of ...
G A Gurzadyan, Gurzadyan G A
exaly   +2 more sources

Galactic planetary nebulae with Wolf-Rayet nuclei

Astronomy and Astrophysics, 2001
We present high resolution spectrophotometric data for a sample of 34 planetary nebulae with [WC] spectral type central stars (WRPNe) in our Galaxy. The observed objects cover a wide range in stellar characteristics: early and late [WC] type stars, as ...
G Stasińska
exaly   +2 more sources

Binary planetary nebulae nuclei towards the Galactic bulge

Astronomy and Astrophysics, 2009
Binarity has been hypothesised to play an important, if not ubiquitous, role in the formation of planetary nebulae (PNe). Yet there remains a severe paucity of known binary central stars required to test the binary hypothesis and to place strong ...
B Miszalski, A Acker, Q A Parker
exaly   +4 more sources

The Nuclei of Planetary Nebulae

Publications of the Astronomical Society of Australia, 1967
For some years now, there have been suggestions that the nuclei of planetary nebulae are stars undergoing a final gravitational contraction to the white dwarf state. These have culminated in two important studies by O’Dell, and by Seaton and his collaborators, the results of which are indicated on the Hertzsprung-Russell diagram of Figure 1.
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The Evolution of the Nuclei of Planetary Nebulae

Publications of the Astronomical Society of Australia, 1972
In the past decade, planetary nebulae have assumed considerable importance in elucidating our understanding of the final stages of stellar evolution at low mass. This began with the work of Shklovsky, O’Dell and Seaton, who showed not only that the nuclei of these nebulae were among the hottest stellar objects, but also that they evolved on a track in ...
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Some Properties of the Nuclei of Old Planetary Nebulae

Publications of the Astronomical Society of the Pacific, 1964
exaly   +2 more sources

Galactic planetary nebulae and evolution of their nuclei

Astrophysics, 1980
The galactic system of planetary nebulae is investigated using previously constructed distance scale and kinematics data. A strong effect of observational selection is established, which has the consequence that with increasing distance, ever brighter and younger objects are observed. More accurate determinations of the spatial and surface densities of
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Nuclei of planetary nebulae and white dwarf envelopes

Astrophysics and Space Science, 1973
Upper bounds to the masses of He envelopes of white dwarfs are derived by examining the maximum He envelope that a nucleus of a planetary nebulae can have consistent with observation.
A. Kovetz, G. Shaviv
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Mass Loss from Nuclei of Planetary Nebulae

1987
Using high resolution ultraviolet spectra taken with the IUE satellite, we study the mass loss process from the nuclei of planetary nebulae (PNN). The measured wind velocities and mass loss rates are combined with other parameters of the nuclei and the surrounding nebulae (e.g.
L. Bianchi, M. Grewing
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On planetary nebula nuclei of the spectral type 'continuous'

Publications of the Astronomical Society of the Pacific, 1994
A detailed reexamination of existing and new International Ultraviolet Explorer (IUE) low-and high-resolution spectra, plus a search of recent literature, shows that for most of the central stars of planetary nebulae the spectral classification previously called 'continuous-type' does not really exist.
openaire   +1 more source