The ionization structure of planetary nebulae. VI - NGC 7662

1986 ◽  
Vol 308 ◽  
pp. 314 ◽  
Author(s):  
T. Barker
Keyword(s):  
Planetary Nebulae ◽  
Ionization Structure ◽  
Ngc 7662

scholarly journals Models of Planetary Nebulae

1978 ◽  
Vol 76 ◽  
pp. 161-161
Author(s):  
M. Perinotto
Keyword(s):  
Ionization Potential ◽  
Neutral Hydrogen ◽  
Planetary Nebulae ◽  
Transfer Reactions ◽  
Line Intensities ◽  
Calculated Line ◽  
Ionization Structure ◽  
Charge Transfer Reactions ◽  
Ngc 7662 ◽  
Astronomy And Astrophysics

From existing models of planetary nebulae an important discrepancy comes out with the low ionization potential ions, as N+ and 0+, whose calculated line intensities are smaller than the observed ones. In this work the effect of charge transfer reactions between single, double, and triple ionized oxygen and nitrogen with neutral hydrogen is taken into account in a model of NGC 7662. The ionization structure of oxygen and nitrogen becomes strongly modified. The computed fractional abundances of 0+ and N+ turn out substantially larger than in previous models, thus helping to reconcile the computed line emissions from low ionization potential ions with the observed ones. (Paper will appear in Astronomy and Astrophysics.)

scholarly journals Ultraviolet spectra of planetary nebulae - VI. NGC 7662

1982 ◽  
Vol 199 (3) ◽  
pp. 517-564 ◽  
Author(s):  
J. P. Harrington ◽  
M. J. Seaton ◽  
S. Adams ◽  
J. H. Lutz
Keyword(s):  
Planetary Nebulae ◽  
Ultraviolet Spectra ◽  
Ngc 7662

High dispersion spectra of Planetary Nebulae

1997 ◽  
Vol 180 ◽  
pp. 242-242
Author(s):  
S. Hyung ◽  
L. H. Aller
Keyword(s):  
Plasma Diagnostics ◽  
Surface Brightness ◽  
High Surface ◽  
Planetary Nebulae ◽  
High Dispersion ◽  
Chemical Compositions ◽  
Echelle Spectrograph ◽  
High Surface Brightness ◽  
Low Surface Brightness ◽  
Ngc 7662

Determinations of the plasma diagnostics and chemical compositions of planetary nebulae require ultimately high dispersion spectra. For objects of high surface brightness the Hamilton Echelle Spectrograph at Lick Observatory is satisfactory for the region 3650–10100Å which involves the 168th to 56th echelle orders. For a slit width of 640 μm amounting to 1.15 arcsec at the Coude focus, the actual spectral resolution (FWHM) is about 0.2Å at 8850Å. The length of the slit is chosen as 4.0 arcsec. Hyung (1994) & Aller (1994) describe the observing procedure. Since the Hamilton echelle was designed primarily for star-like sources, it is not useful for extended low surface brightness PN. The earlier observations were obtained with an 800 × 800 chip that did not cover the echelle field, so several settings were needed. Later, we used a slower 2048 × 2048 chip which covered the whole field and was somewhat more efficient at longer wavelengths. The program has been completed and definitive measurements have obtained for NGC 2440, NGC 6543, NGC 6741, NGC 6818, NGC 7026, NGC 7662, and Hu 1-2. All of these PN display particularly rich, interesting spectra. Previously observed and published objects include IC 351, IC 418, IC 2149, IC 4997, NGC 6567, NGC 6572, NGC 6790, NGC 6886, NGC 7009, BD +30 3639, & Hubble 12. NGC 6884 is in press. Additional nebulae which are yet to be discussed are IC 4634, IC 4846, IC 5117, NGC 6210, & NGC 6803.

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.

Sign in / Sign up

Export Citation Format

Share Document