Observations of circular polarization in white dwarfs and the nuclei of planetary nebulae

Astrophysics ◽  
1974 ◽  
Vol 8 (3) ◽  
pp. 205-209
Author(s):  
O. S. Shulov ◽  
E. T. Belokon'
Keyword(s):  
Circular Polarization ◽  
White Dwarfs ◽  
Planetary Nebulae

The Effect of Magnetic Field Spread and Temperature and Density Variations in Cyclotron Emission Regions

1987 ◽  
Vol 7 (2) ◽  
pp. 123-127 ◽  
Author(s):  
D. T. Wickramasinghe ◽  
Lilia Ferrario
Keyword(s):  
Magnetic Field ◽  
Point Source ◽  
Circular Polarization ◽  
White Dwarfs ◽  
Type Systems ◽  
Polar Cap ◽  
Cyclotron Radiation ◽  
Cyclotron Emission ◽  
Source Models ◽  
Accretion Shocks

AbstractWe discuss the properties of cyclotron radiation from accretion shocks located above the atmospheres of magnetic white dwarfs taking into account the effects of field spread and density and temparture structure. The models which are an improvement on previous point source models are shown to have characteristics that are in better overall agreement with the properties of AM Herculis type systems. Our calculations of the polarization properties of large polar cap emission regions are used to discuss the recent null measurements of circular polarization in DQ Herculis type systems.

scholarly journals Family links between Planetary Nebulae nuclei and cataclysmic variables, binary white dwarfs, R CrB stars, and SNe IA

1997 ◽  
Vol 180 ◽  
pp. 85-90
Author(s):  
L.R. Yungelson ◽  
A.V. Tutukov
Keyword(s):  
White Dwarfs ◽  
Cataclysmic Variables ◽  
Planetary Nebulae ◽  
Close Binaries ◽  
Symbiotic Stars

We analyse the population of PNe and links between binary PNNi and stars which are in the later evolutionary stages. In a model which assumes that all stars are born in binaries, about 16% of PN result from ejection of common envelopes in close binaries, 85% of single PNNi are formed by merger of components of binaries. In the model, 5% of PNNi may be precataclysmic binaries, 5% may be precursors of symbiotic stars, 0.4% may be pre-SN Ia, 0.1% - precursors of hydrogen-deficient giants. About 0.1% of all PNe may be hydrogen-deficient.

scholarly journals NLTE analysis of central stars of highly excited Planetary Nebulae

1997 ◽  
Vol 180 ◽  
pp. 132-132
Author(s):  
T. Rauch ◽  
J. Köppen ◽  
R. Napiwotzki ◽  
K. Werner
Keyword(s):  
White Dwarfs ◽  
State Of The Art ◽  
Planetary Nebulae ◽  
Evolutionary Status ◽  
Agb Stars ◽  
Spectral Analyses ◽  
Central Stars

Very hot central stars (CSPN) of highly excited planetary nebulae (PN) display directly the formation of white dwarfs. Only a few of these CSPN have been analyzed so far due to their low brightness and thus, the interpretation of their evolutionary status is hampered by statistical incompleteness. In the last decade many spectral analyses of very hot post-AGB stars by means of state-of-the-art NLTE model atmospheres have been performed (e.g. Rauch et al. 1996; Werner & Rauch 1994; Rauch & Werner 1995) and our picture of post-AGB evolution has been improved.

scholarly journals A High Resolution Far-UV Spectral Atlas of CSPNs and Hot White Dwarfs

1993 ◽  
Vol 155 ◽  
pp. 91-91
Author(s):  
R.W. Tweedy
Keyword(s):  
High Resolution ◽  
White Dwarfs ◽  
Planetary Nebulae ◽  
Central Star ◽  
Evolutionary Sequence ◽  
Spectroscopic Analyses ◽  
Spectroscopic Information ◽  
The University ◽  
Phd Thesis ◽  
Central Stars

A high-resolution IUE spectral atlas of central stars of planetary nebulae and hot white dwarfs has been produced (part of Tweedy, 1991, PhD thesis from the University of Leicester, UK), and examples from it are shown here. It has been sorted into an approximate evolutionary sequence, based on published spectroscopic analyses, from the cool 28,000K young central star He 2–138, through the hot objects like NGC 7293 and NGC 246 at 90,000K and 130,000K respectively, down to 40,000K DA white dwarfs like GD 2, which is the chosen cutoff for this selection. Copies of a revised version of this atlas, which will include more recent spectroscopic information and also white dwarfs down to 35,000K – to include the Si III object GD 394 – will be sent to anyone who requests one.

scholarly journals From Planetary Nebulae to White Dwarfs: Constraints from the Asteroseismology of the Pulsating Planetary Nebula Central Star RXJ 2117+3412

2002 ◽  
Vol 185 ◽  
pp. 610-611
Author(s):  
P. Moskalik ◽  
G. Vauclair
Keyword(s):  
Planetary Nebula ◽  
White Dwarfs ◽  
Planetary Nebulae ◽  
Central Star

AbstractWe summarize the results of an asteroseismological study of the pulsating planetary nebula central star RXJ 2117+3412.

scholarly journals Appendix A: A Catalog of Hydrogen-Deficient Stars

1985 ◽  
Vol 87 ◽  
pp. 498-506
Author(s):  
J.S. Drilling ◽  
P.W. Hill
Keyword(s):  
Data Base ◽  
White Dwarfs ◽  
Planetary Nebulae ◽  
Basic Data ◽  
Complete List ◽  
Central Stars

The following four tables were originally presented as part of the paper entitled ‘Basic Data on Hydrogen-Deficient Stars’ by J. S. Drilling, which appears earlier in this volume. A number of corrections and additions have been made by the participants, mostly by P. W. Hill using the SIMBAD data base. A much improved version of the catalog therefore follows. Helium-rich central stars of planetary nebulae, helium-rich white dwarfs, and Wolf-Rayet stars are not included. A complete list of helium-rich central stars is given by Mendez et al. elsewhere in this volume.

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