The ionization structure of planetary nebulae. VII. New observations of the Ring Nebula

1987 ◽  
Vol 322 ◽  
pp. 922 ◽  
Author(s):  
Timothy Barker
Keyword(s):  
Planetary Nebulae ◽  
Ionization Structure ◽  
Ring Nebula

scholarly journals The Three-Dimensional Ionization Structure and Evolution of NGC 6720, The Ring Nebula

2007 ◽  
Vol 134 (4) ◽  
pp. 1679-1692 ◽  
Author(s):  
C. R. O'Dell ◽  
F. Sabbadin ◽  
W. J. Henney
Keyword(s):  
Three Dimensional ◽  
Ionization Structure ◽  
Ring Nebula

scholarly journals Dust in Planetary Nebulae: Observational Considerations

1978 ◽  
Vol 76 ◽  
pp. 275-279
Author(s):  
Bruce Balick
Keyword(s):  
Chemical Properties ◽  
Planetary Nebulae ◽  
Substantial Fraction ◽  
Ir Radiation ◽  
Ionization Structure ◽  
And Chemical Properties

The question of dust in planetary nebulae dates back a decade to the first then unexpected discoveries of strong infrared (IR) excesses in planetary nebulae (Gillett et al. 1967; Woolf 1969; Gillett and Stein 1969, 1970; Neugebauer and Garmire 1970; Willner et al. 1972). It has been clear from the outset that a substantial fraction, if not most, of the nebular luminosity is somehow converted to IR radiation by the dust. Two important questions are whether, and to what extent, dust influences the ionization structure and chemical properties of the nebula.

scholarly journals New advances in the field of planetary nebulae from ultraviolet observations

2011 ◽  
Vol 7 (S283) ◽  
pp. 45-52 ◽  
Author(s):  
Luciana Bianchi
Keyword(s):  
Planetary Nebulae ◽  
Ionic Species ◽  
Physical Parameters ◽  
Mass Relation ◽  
Chemical Enrichment ◽  
Intermediate Mass Stars ◽  
Ionization Structure ◽  
C And N ◽  
Ultraviolet Observations ◽  
Critical Constraints

AbstractThe ultraviolet (UV) domain, in particular shortwards of Lyα, provides unique information to unravel the physical parameters of Central Stars of Planetary Nebulae (CSPNe) and the paths for this elusive final stage of stellar evolution, thanks to a wealth of diagnostic transitions from ionic species not observable at other wavelengths. Intermediate mass stars are the major providers of important elements like C and N. Understanding how they shed most of their initial mass is critical for understanding the chemical enrichment of the ISM. Mass-loss diagnostic lines abound at UV wavelengths, and when the CSPN reaches the hottest Teff before turning on the WD-cooling sequence, and the wind fades, the last wind lines to disappear are found in the far-UV, as well as diagnostic lines for elements such as Ne. This domain also offers a host of H2 transitions, tracing the circum-stellar material expelled in previous phases. UV images and spectra of PNe add critical constraints to their ionization structure and to some abundances. Finally, the recent GALEX sky surveys in two UV bands afforded the first unbiased census of hot white dwarfs (WD) and post-AGB objects in the Milky Way, significantly expanding known catalogs and providing statistical constraints to the initial-final mass relation.

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