Results 21 to 30 of about 163 (129)
Binary Nuclei of Planetary Nebulae [PDF]
Symposium - International Astronomical Union, 1978 In view of the spectral similarity and the probable evolutionary relation between certain planetary nebulae (PN) and other objects that are generally binaries (symbiotic stars, Be stars, or slow novae), it is probable that many nuclei of PN are double.
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CCD Images of Three Planetary Nebulae With Binary Nuclei [PDF]
Symposium - International Astronomical Union, 1989 A 14, H 3-75 and K 1-2, three planetary nebulae with binary nuclei, were imaged with narrow-band [N II], Ha, [O III] and He II filters by using the TI CCD chip on the 0.9-m telescope at CTIO. The purpose of doing the observing was to see if planetaries with known binary nuclei exhibit particularly peculiar morphologies.
Julie Lutz, Nancy Jo Lame
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Planetary Nebulae by Binary Nuclei [PDF]
Symposium - International Astronomical Union, 1993 Planetary nebulae with close binary nuclei are reviewed. It is shown that these systems can be used as a source of information for the physics of the common envelope phase in the evolution of binary systems. Mechanisms for the production of bipolar planetary nebulae are examined and it is concluded that presently the action of binary companions to the ...
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Abell-35 Phenomena in Symbiotic Stars: Discovery of 1.2 and 6.4 Day Periods in VV8 (V471 Per)
Open Astronomy, 2012 We have collected high precision optical photometry of VV8, so far 782 individual observing runs uniformly distributed over the period 2005 - 2011. This dataset allows us to refine the known long periodicity of VV8 to P = 16.8 yr, with peak-to-valley ...
Munari U. +10 more
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On the Variability of the Nuclei of Three Planetary Nebulae [PDF]
Symposium - International Astronomical Union, 1968 The observations of nuclei of three planetary nebulae, NGC 6826, NGC 7662 and IC 4593, have been made as part of a more extensive program with the aim of obtaining their absolute spectrophotometric gradients (ϕ) and photographic magnitudes (from the spectrogram). The spectra were obtained with an 8–12′ Schmidt telescope combined with an objective prism
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Atoms, 2014 We review studies of two kinds of dips in spectral line profiles emitted by plasmas—dips that have been predicted theoretically and observed experimentally: Langmuir-wave-caused dips (L-dips) and charge-exchange-caused dips (X-dips). There is a principal
Elisabeth Dalimier +2 more
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Models for Nuclei of Planetary Nebulae and for Ultraviolet Stars [PDF]
Symposium - International Astronomical Union, 1974 A series of stellar models were evolved, all with a total mass of 0.65 M⊙, an initial carbon-oxygen core of mass 0.60 M⊙, an intermediate helium mantle and an outer hydrogen-rich envelope with mass varying from case to case. Although the most hydrogen-rich cases resulted in red giants, cases with ≲ 0.01 M⊙ in the hydrogen envelope evolved at high ...
J. Katz, R. Malone, E. E. Salpeter
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Whither or Wither the Sulfur Anomaly in Planetary Nebulae?
The Astrophysical Journal LettersWe present a thorough investigation of the long-standing sulfur anomaly enigma. Our analysis uses chemical abundances from the most extensive data set available for 126 planetary nebulae (PNs) with improved accuracy and reduced uncertainties from a 10° ×
Shuyu Tan, Quentin A. Parker
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The Properties of Planetary Nebulae Nuclei: Stellar Winds [PDF]
Symposium - International Astronomical Union, 1993 We present IUE observations of some nuclei of Planetary Nebulae. From these data we derive the stellar photospheric parameters (Teff Lbol, log g), and the wind characteristics (velocity, mass loss rate). Teff, R∗, Lbol are derived from UV low resolution spectra, combining optical and radio data, from Bianchi (1988) or from new IUE data, with the same ...
L. Bianchi, G. De Francesco
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The Secular Evolution of Planetary Nebula IC 418 and Its Implications for Carbon Star Formation
The Astrophysical Journal LettersThe rate of stellar evolution can rarely be measured in real time. The fastest evolution (excluding event-driven evolution), where stars may evolve measurably over decades, is during the post–Asymptotic Giant Branch (AGB) phase. In this Letter we provide
Albert A. Zijlstra, Quentin A. Parker
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