scholarly journals IUE and Optical Observations of HE 2-104

1988 ◽  
Vol 103 ◽  
pp. 305-306
Author(s):  
Julie H. Lutz
Keyword(s):  
Planetary Nebula ◽  
Optical Observations ◽  
Symbiotic Star ◽  
High Excitation ◽  
Ultraviolet Spectra ◽  
Evolutionary State ◽  
Very High

AbstractHe 2-104 has been classified as both a planetary nebula and as a symbiotic star. Optical and ultraviolet spectra and CCD images have been obtained in order to learn more about the evolutionary state of this object. The spectra of the object indicate that it could be either a symbiotic star or a very high excitation planetary nebula. The CCD images show a nebulosity with a radius of about 4 seconds of arc and faint bipolar outer structures extending out approximately 25 seconds of arc from the center of the nebula.

The Symbiotic Star H1-36

1983 ◽  
Vol 5 (2) ◽  
pp. 211-213 ◽  
Author(s):  
David A. Allen
Keyword(s):  
Emission Line ◽  
Planetary Nebula ◽  
Line Spectrum ◽  
Symbiotic Star ◽  
Symbiotic Stars ◽  
High Excitation ◽  
Infrared Excess ◽  
Emission Line Spectrum ◽  
Definition Of ◽  
Meaningful Definition

Since its discovery by Haro (1952) the star H1-36 has been catalogued as a planetary nebula despite its extremely high-excitation emission-line spectrum (e.g. [Fe VII], [Ne V]) and its imposing, variable infrared excess. Because its optical spectrum resembled those of many symbiotic stars, I have persistently classified H1-36 as such. A meaningful definition of a symbiotic star would necessarily include both the high-excitation emission-line spectrum and the presence of a cool (usually M-type or Mira) giant.

The High‐Excitation Planetary Nebula NGC 7662

1997 ◽  
Vol 491 (1) ◽  
pp. 242-253 ◽  
Author(s):  
Siek Hyung ◽  
Lawrence H. Aller
Keyword(s):  
Planetary Nebula ◽  
High Excitation ◽  
Ngc 7662

Symbiotic star AS 201: A planetary nebula

1987 ◽  
Vol 131 (1-2) ◽  
pp. 781-784 ◽  
Author(s):  
L. Kohoutek
Keyword(s):  
Planetary Nebula ◽  
Symbiotic Star

Very High Excitation Lines of H2 in the Orion Molecular Cloud Outflow

2017 ◽  
Vol 837 (1) ◽  
pp. 83 ◽  
Author(s):  
T. R. Geballe ◽  
M. G. Burton ◽  
R. E. Pike
Keyword(s):  
Molecular Cloud ◽  
High Excitation ◽  
Very High

scholarly journals The IUE Ultraviolet Spectrum of PC 11

1993 ◽  
Vol 155 ◽  
pp. 398-398 ◽  
Author(s):  
M. Parthasarathy ◽  
S.R. Pottasch ◽  
J. Clavel
Keyword(s):  
Short Wavelength ◽  
Planetary Nebula ◽  
Significant Variation ◽  
Central Star ◽  
Ultraviolet Spectrum ◽  
Emission Lines ◽  
Symbiotic Star ◽  
Iras Source ◽  
Long Wavelength ◽  
Cold Dust

PC 11 (HD 149427, PK 331-5 1) is classified as a young planetary nebula with strong OIII 4363Å and a Zanstra temperature of TZ = 27000K. It is also classified as (D′ — type) yellow symbiotic star with A — F type companion. It is an IRAS source with detached cold dust with far intrared (IRAS) colours similar to planetary nebulae. The IUE short wavelength (SWP) spectra show emission lines due to OIII] (1661/1666Å). NIII] (1746/1754Å) CIII] (1907/1909Å). The OIII] and NIII] emission lines show significant variation. Variation in the strength of CIII] is not very significant. The strength of OIII] has decreased and NIII] has increased. The long wavelength (LWP) spectrum shows stellar continuum (A-F) and absorption lines due Mg II 2800Å feature. It also show emission lines at 2772Å (?) 3133Å −3140Å (very strong) (OIII, [FeV], 3209Å (He II?) ([FEII]). The variation in the strength of emission line due OIII] and NIII] and the presence of stellar continuum (A-F) suggests that the central star of PC 11 is a binary.

scholarly journals Models of Planetary Nebulae: Generalisation of the Multiple Winds Model

1989 ◽  
Vol 131 ◽  
pp. 411-424 ◽  
Author(s):  
F. D. Kahn
Keyword(s):  
Planetary Nebula ◽  
High Speed ◽  
Planetary Nebulae ◽  
Central Star ◽  
Theoretical Description ◽  
Basic Theory ◽  
Spectral Lines ◽  
High Excitation ◽  
General Shape ◽  
Fast Wind

According to the multiple winds model a planetary nebula forms as the result of the interaction of a fast wind from the central star with the superwind that had previously been emitted by the progenitor star. The basic theory which deals with the spherically symmetrical case is briefly summarised. Various improvements are then considered in turn. A better history is clearly needed of the way that the central star becomes hotter, it is unrealistic to make the assumption that the superwind is spherically symmetrical, and finally there are likely to be important instabilities at some of the interfaces in the PN, notably that between the shocked superwind and the HII layer. These changes in the theoretical description produce a better understanding of the conditions in the outer parts of a PN and of the nature of its general shape, and they should lead to an explanation for the occurrence of high speed motions, and of highly ionized species and high excitation spectral lines.

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