scholarly journals The Metal-Line Spectra of Central Stars of Planetary Nebulae

1989 ◽  
Vol 131 ◽  
pp. 317-317
Author(s):  
M. Roth ◽  
A. Herrero ◽  
R. H. Mendez ◽  
R. P. Kudritzki ◽  
K. Butler ◽  
...  
Keyword(s):  
High Resolution ◽  
Planetary Nebulae ◽  
Line Formation ◽  
Echelle Spectrograph ◽  
Metal Line ◽  
Metal Abundances ◽  
Central Stars

We present spectral descriptions based on high-resolution spectrograms of central stars of planetary nebulae, obtained with the ESO 3,6-m telescope + CASPEC (Cassegrain Echelle Spectrograph). We make preliminary determinations of stellar photospheric metal abundances, using non-LTE model atmospheres and non-LTE line formation calculations.

scholarly journals An empirical analysis of the stellar wind and Planetary Nebulae of the [WC10] central stars CPD–56° 8032 and He 2–113

1997 ◽  
Vol 180 ◽  
pp. 100-101
Author(s):  
Orsola de Marco ◽  
M. J. Barlow ◽  
P. J. Storey
Keyword(s):  
Empirical Analysis ◽  
Stellar Wind ◽  
Planetary Nebulae ◽  
Line Formation ◽  
Recombination Line ◽  
Echelle Spectrograph ◽  
Formation Region ◽  
Central Stars ◽  
Line Analysis

[WC] stars are H–deficient central stars of PN which have developed a dense, fast stellar wind. Their spectra can mimic the spectra of massive (Min∼5OM⊙) Wolf-Rayet stars of the carbon sequence. Deriving their parameters is of importance both in understanding the PN and the Wolf-Rayet phenomena. Spectra of both objects were obtained at the AAT in May 1993 with the UCL Echelle Spectrograph (3500–9200 å, R=50,0000). The reddening, determined from comparing the Hβ nebular line fluxes with radio fluxes from Purton et al. (MNRAS 128, 321, 1982), yielded E(B-V)=0.68 (CPD–56° 8032) and 1.00 (He 2–113). Distances are derived using two different methods and they agree within the relative uncertainties. They are 1.35 and 1.50 kpc for CPD–56° 8032 and He 2–113, respectively. The electron temperatures of the C ii line formation region in the wind is derived from a recombination line analysis (20,000 and 17,000 K for CPD–56° 8032 and He 2–113, respectively). From the same stellar wind recombination line analysis, we find C/He=0.12 and 0.16, together with O/He=0.19 and 0.25, for CPD–56° 8032 and He 2–113 respectively.

The Metal-Line Spectra of Central Stars of Planetary Nebulae

1989 ◽  
pp. 317-317
Author(s):  
M. Roth ◽  
A. Herrero ◽  
R. H. Méndez ◽  
R. P. Kudritzki ◽  
K. Butler ◽  
...  
Keyword(s):  
Planetary Nebulae ◽  
Metal Line ◽  
Central Stars

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 Planetary Nebulae with binary nuclei

1997 ◽  
Vol 180 ◽  
pp. 74-84 ◽  
Author(s):  
Mario Livio
Keyword(s):  
High Resolution ◽  
Crucial Role ◽  
Binary Systems ◽  
Planetary Nebulae ◽  
Specific Mechanism ◽  
Essential Information ◽  
Common Envelope ◽  
High Resolution Images ◽  
The Common ◽  
Central Stars

High resolution images of planetary nebulae have revealed a variety of non-spherical morphologies. In addition, some planetary nebulae were found to produce highly collimated jets. It is argued that binary central stars may play a crucial role in the production of all of these morphologies. In particular, a specific mechanism is identified for the generation of “point-symmetric” nebulae. It is shown that the study of binary nuclei of planetary nebulae can provide essential information for the understanding of the common envelope phase in the evolution of binary systems.

scholarly journals A FUSE View of Winds from the Central Stars of Planetary Nebulae

2010 ◽  
Vol 27 (2) ◽  
pp. 210-213 ◽  
Author(s):  
Martín A. Guerrero ◽  
Gerardo Ramos-Larios ◽  
Derck Massa
Keyword(s):  
High Resolution ◽  
Systematic Study ◽  
Spectral Resolution ◽  
Preliminary Analysis ◽  
Planetary Nebulae ◽  
Uv Spectra ◽  
High Spectral Resolution ◽  
Stellar Winds ◽  
First Time ◽  
Central Stars

AbstractSince the IUE satellite produced a vast collection of high-resolution UV spectra of the central stars of planetary nebulae (CSPNe), there has not been any further systematic study of the stellar winds of these stars. The high spectral resolution, sensitivity and large number of archival observations in the FUSE archive allow the study of the stellar winds of CSPNe in the far-UV domain where lines of species spanning a wide excitation range can be observed. We present here a preliminary analysis of the P Cygni profiles of a sample of ∼60 CSPNe observed by FUSE. P Cygni profiles providing evidence for fast stellar winds with velocities between 200 and 4300 km s−1 have been found in 40 CSPNe. In many cases, this is the first time that fast stellar winds have been reported for these planetary nebulae (PNe). A detailed study of these far-UV spectra is on-going.

scholarly journals Unified Model Atmosphere Studies of Central Stars of Planetary Nebulae

1993 ◽  
Vol 155 ◽  
pp. 82-82
Author(s):  
R. Gabler ◽  
A. Gabler ◽  
R. H. Méndez ◽  
R. P. Kudritzki
Keyword(s):  
High Resolution ◽  
Absorption Line ◽  
Spectroscopic Analysis ◽  
Planetary Nebulae ◽  
Model Atmosphere ◽  
Unified Model ◽  
Parallel Model ◽  
Line Profiles ◽  
Atmospheric Parameters ◽  
Central Stars

A first step in the accurate quantitative spectroscopic analysis of central stars of PN has been based on fitting the results of NLTE, hydrostatic, plane-parallel model atmosphere calculations to the observed H and He absorption-line profiles in high-resolution spectra of bright central stars (Méndez et al. 1988, A&A 190, 113 and subsequent papers). Such analyses have provided very useful determinations of the basic atmospheric parameters: Teff, log g and He abundance.

scholarly journals Helium Rich Subdwarf O Stars and Central Stars of Planetary Nebulae

1985 ◽  
Vol 87 ◽  
pp. 322-343
Author(s):  
R.H. Méndez ◽  
C.H. Miguel ◽  
U. Heber ◽  
R.P. Kudritzki
Keyword(s):  
Absorption Line ◽  
Planetary Nebulae ◽  
Model Atmosphere ◽  
Evolutionary Status ◽  
Line Formation ◽  
Line Profiles ◽  
Plane Parallel ◽  
Computational Work ◽  
Work First ◽  
Central Stars

In this review we will discuss the hottest subluminous H-deficient stars, namely those with Teff > 30000 K. In the absence of reliable distance determinations for hot subluminous stars, the best way to discuss their properties and evolutionary status is to find their positions on the log g - log Teff diagram. In the last few years, after extensive computational work, first in Kiel and more recently also in Munich, it has become possible to obtain log g and Teff, together with the surface He abundance, directly by fitting the observed H and He absorption line profiles with theoretical profiles obtained from non-LTE model atmospheres and associated line formation codes. The non-LTE models are plane-parallel, in hydrostatic and radiative equilibrium, and the atmosphere is assumed to consist of H and He only. A recent paper by Groth et al. (1985) gives most of the references on the application of this non-LTE model atmosphere approach to the study of all kinds of hot subluminous stars.

scholarly journals Echelle Spectra of a Large Sample of Planetary Nebula Nuclei

1989 ◽  
Vol 131 ◽  
pp. 316-316
Author(s):  
James K. McCarthy
Keyword(s):  
High Resolution ◽  
Absorption Line ◽  
Planetary Nebula ◽  
Planetary Nebulae ◽  
The Sun ◽  
Line Profiles ◽  
Large Sample ◽  
Central Stars

We have undertaken at Palomar Observatory to obtain high resolution spectra of a large sample of planetary nebula nuclei (PNN) in order to systematically investigate their spectral morphologies and then to derive temperatures and surface gravities by comparing absorption line profiles to model atmospheres. We have taken as our sample all those central stars of planetary nebulae within 1.3 kpc of the sun according to the distance determinations of Daub (Ap, J., 260, 612, 1982); of the 94 objects in this unbiased sample, 64 are in the sky visible from Palomar and 33 have central stars bright enough to be observed at a resolution of 5 000 with an “echellette” spectrograph on the 5-m Hale telescope, leaving 7 PNN (11% of the northern sample of 64 PNN) which are too faint to be observed at present.

scholarly journals Mass Loss in Two Low Temperature Central Stars of Planetary Nebulae

1993 ◽  
Vol 155 ◽  
pp. 93-93
Author(s):  
A. Modigliani ◽  
M. Perinotto ◽  
P. Patriarchi
Keyword(s):  
High Resolution ◽  
Low Temperature ◽  
Mass Loss ◽  
Planetary Nebulae ◽  
Fast Wind ◽  
Central Stars

The high resolution IUE images SWP 16742 and SWP 42675 have been studied to derive the fast wind properties of the central stars of the two low temperature planetary nebulae IC 2149 and Tc 1. The first image is from the IUE archive, while the second one has been taken by us.

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