scholarly journals Observational Aspects of the Evolution of Planetary Nebulae and their Central Stars

1968 ◽  
Vol 34 ◽  
pp. 359-375
Author(s):  
C.R. O'Dell
Keyword(s):  
Stellar Evolution ◽  
Planetary Nebulae ◽  
Physical Nature ◽  
Significant Phase ◽  
The Many ◽  
Central Stars ◽  
Considerable Insight

The greatest activity in the area of evolution of the central stars of the planetary nebulae has occurred in the last two decades, although there have been significant contributions by many workers of considerable insight ever since the early studies at the Lick Observatory demonstrated the physical nature of this class of nebula. We shall try to draw together here the many facets of the present picture of this rapidly developing and highly significant phase of stellar evolution. Unfortunately, the picture is not at all as complete as one would like, and there remain several points of scientific contention; however, we should like to present the results of several investigators. A certain amount of redundancy with previous papers given prior will be necessary, but we shall endeavor to treat these topics briefly and in the context of the evolution of the nebulae and their stars.

scholarly journals Catalogue of the central stars of planetary nebulae

2020 ◽  
Vol 640 ◽  
pp. A10
Author(s):  
W. A. Weidmann ◽  
M. B. Mari ◽  
E. O. Schmidt ◽  
G. Gaspar ◽  
M. M. Miller Bertolami ◽  
...  
Keyword(s):  
Stellar Evolution ◽  
Late Stage ◽  
Planetary Nebulae ◽  
Surface Gravity ◽  
Physical Parameters ◽  
Evolutionary Models ◽  
Pertinent Information ◽  
Central Stars ◽  
Statistical Improvement ◽  
Magnitude Estimates

Planetary nebulae represent a potential late stage of stellar evolution, however, their central stars (CSPNe) are relatively faint and, therefore, pertinent information is available for merely < 20% of the Galactic sample. Consequently, the literature was surveyed to construct a new catalogue of 620 CSPNe featuring important spectral classifications and information. The catalogue supersedes the existing iteration by 25% and includes physical parameters such as luminosity, surface gravity, temperature, magnitude estimates, and references for published spectra. The marked statistical improvement enabled the following pertinent conclusions to be determined: the H-rich/H-poor ratio is 2:1, there is a deficiency of CSPNe with types [WC 5-6], and nearly 80% of binary central stars belong to the H-rich group. The last finding suggests that evolutionary scenarios leading to the formation of binary central stars interfere with the conditions required for the formation of H-poor CSPN. Approximately 50% of the sample with derived values of log L⋆, log Teff, and log g, exhibit masses and ages consistent with single stellar evolutionary models. The implication is that single stars are indeed able to form planetary nebulae. Moreover, it is shown that H-poor CSPNe are formed by higher mass progenitors. The catalogue is available through the Vizier database.

scholarly journals Proto-Planetary Nebulae

2003 ◽  
Vol 209 ◽  
pp. 113-120 ◽  
Author(s):  
Bruce J. Hrivnak
Keyword(s):  
Stellar Evolution ◽  
Planetary Nebula ◽  
Planetary Nebulae ◽  
Asymptotic Giant Branch ◽  
Central Stars

The study of proto-planetary nebulae (PPNs) leads to a better understanding of both the preceding asymptotic giant branch and the succeeding planetary nebula phases of stellar evolution. Recent results are reviewed, emphasizing the properties of the central stars and the shape and chemistry of the nebulae. The study of PPNs is seen to be important in its own right.

Model Atmospheres and Quantitative Spectroscopy of Central Stars of Planetary Nebulae

1989 ◽  
Vol 131 ◽  
pp. 273-292 ◽  
Author(s):  
R. P. Kudritzki ◽  
R.H. Méndez
Keyword(s):  
Quantitative Analysis ◽  
Planetary Nebulae ◽  
Physical Nature ◽  
Black Body ◽  
Central Star ◽  
Model Atmosphere ◽  
Stellar Atmospheres ◽  
Spectral Lines ◽  
Quantitative Spectroscopy ◽  
Central Stars

It is a good tradition in IAU Symposia about PN to have a paper on model atmospheres. However, this is always a difficult task for the authors, because the majority of the PN researchers still believe that the best model atmosphere for a Central Star is a black body. Of course, this puts a theorist in stellar atmospheres into a somewhat desperate position. However, Central Stars of Planetary Nebulae (hereafter CSPN) - as all other stars - show spectral lines. And we will try to use the opportunity of this paper to convince that - as for all other stars - the quantitative analysis of these lines on basis of model atmospheres yields extremely valuable information about the physical nature of the stars.

scholarly journals Are planetary nebulae derived from multiple evolutionary scenarios?

2011 ◽  
Vol 7 (S283) ◽  
pp. 192-195 ◽  
Author(s):  
David J. Frew ◽  
Quentin A. Parker
Keyword(s):  
Stellar Evolution ◽  
Planetary Nebulae ◽  
Evolution Theory ◽  
Population Synthesis ◽  
Evolutionary Pathways ◽  
Central Stars

AbstractOur understanding of planetary nebulae has been significantly enhanced as a result of several recent large surveys (Parker et al., these proceedings). These new discoveries suggest that the ‘PN phenomenon’ is in fact more heterogeneous than previously envisaged. Even after the careful elimination of mimics from Galactic PN catalogues, there remains a surprising diversity in the population of PNe and especially their central stars. Indeed, several evolutionary scenarios are implicated in the formation of objects presently catalogued as PNe. We provide a summary of these evolutionary pathways and give examples of each. Eventually, a full census of local PNe can be used to confront both stellar evolution theory and population synthesis models.

scholarly journals Spectra of the Central Stars of Planetary Nebulae

1968 ◽  
Vol 34 ◽  
pp. 339-354 ◽  
Author(s):  
Lawrence H. Aller
Keyword(s):  
Observational Data ◽  
Stellar Evolution ◽  
Planetary Nebulae ◽  
Spectral Energy ◽  
Spectral Energy Distributions ◽  
Energy Distributions ◽  
Spectroscopic Observations ◽  
Theoretical Investigations ◽  
Late Stages ◽  
Central Stars

The central stars of planetary nebulae represent seemingly well-defined late stages of stellar evolution. Theoretical investigations with predictions of evolutionary tracks impose difficult requirements for observational data. Measurements of spectral energy distributions, of colors, and of magnitudes, and spectroscopic observations are all urgently needed.

scholarly journals 12. The Nuclei of Planetary Nebulae as Progenitors of White Dwarfs

1971 ◽  
Vol 42 ◽  
pp. 77-78
Author(s):  
C. R. O'Dell
Keyword(s):  
Stellar Evolution ◽  
Planetary Nebula ◽  
White Dwarfs ◽  
Rapid Change ◽  
Planetary Nebulae ◽  
Review Article ◽  
The Past ◽  
The Subject ◽  
Central Stars

Stellar evolution is characterized by fast and slow phases. Usually the periods of rapid change are difficult to follow observationally; but, this does not seem to be the case when passing through the planetary nebula stage. Because of their high intrinsic luminosities and easy identification, it is possible to identify and study these objects and their central stars rather completely. It is quite relevant to discuss these objects at a symposium on white dwarfs since the central stars may be in the immediate progenitor stage before white dwarfs. The actual picture of the evolution of the nuclei has changed rather little in the past few years and is the subject of an earlier review article (O'Dell, 1968) to which the reader is referred.

scholarly journals Towards an improvement in the spectral description of central stars of planetary nebulae

2018 ◽  
Vol 614 ◽  
pp. A135 ◽  
Author(s):  
W. Weidmann ◽  
R. Gamen ◽  
D. Mast ◽  
C. Fariña ◽  
G. Gimeno ◽  
...  
Keyword(s):  
Stellar Evolution ◽  
Planetary Nebulae ◽  
Emission Lines ◽  
Spectral Classification ◽  
High Quality ◽  
Isaac Newton ◽  
Type Spectrum ◽  
First Time ◽  
Central Stars ◽  
Preliminary Classification

Context. There are more than 3000 known Galactic planetary nebulae, but only 492 central stars of Galactic planetary nebulae (CSPN) have known spectral types. It is vital to increase this number in order to have reliable statistics, which will lead to an increase of our understanding of these amazing objects. Aims. We aim to contribute to the knowledge of central stars of planetary nebulae and stellar evolution. Methods. This observational study is based on Gemini Multi-Object Spectrographs (GMOS) and with the Intermediate Dispersion Spectrograph (IDS) at the Isaac Newton Telescope spectra of 78 CSPN. The objects were selected because they did not have any previous classification, or the present classification is ambiguous. These new high quality spectra allowed us to identify the key stellar lines for determining spectral classification in the Morgan-Keenan (MK) system. Results. We have acquired optical spectra of a large sample of CSPN. From the observed targets, 50 are classified here for the first time while for 28 the existing classifications have been improved. In seven objects we have identified a P-Cygni profile at the He I lines. Six of these CSPN are late O-type. The vast majority of the stars in the sample exhibit an absorption-type spectrum, and in one case we have found wide emission lines typical of [WR] stars. We give a complementary, and preliminary, classification criterion to obtain the sub-type of the O(H)-type CSPN. Finally, we give a more realistic value of the proportion of CSPN that are rich or poor in hydrogen.

scholarly journals Late Stages of Stellar Evolution

1995 ◽  
Vol 166 ◽  
pp. 173-180
Author(s):  
P. Thejll
Keyword(s):  
Stellar Evolution ◽  
White Dwarfs ◽  
Planetary Nebulae ◽  
High Accuracy ◽  
Current Understanding ◽  
Large Numbers ◽  
Hot Subdwarfs ◽  
Late Stages ◽  
Central Stars

A review is given of the use of high-accuracy astrometry on research on white dwarfs and the hot subdwarfs and central stars of planetary nebulae (CSPN). Predictions are made about the expected impact of HIPPARCOS, and the possible impacts of GAIA and ROEMER. Discovery of large numbers of new white dwarfs is expected, and, for the more distant hot subdwarfs and CSPN, important refinements of our current understanding of these objects. For white dwarfs independent values of mass and radius may be accurate enough to allow new understanding of the internal composition.

scholarly journals Spectral analysis of the hybrid PG 1159-type central stars of the planetary nebulae Abell 43 and NGC 7094

2019 ◽  
Vol 489 (1) ◽  
pp. 1054-1071 ◽  
Author(s):  
L Löbling ◽  
T Rauch ◽  
M M Miller Bertolami ◽  
H Todt ◽  
F Friederich ◽  
...  
Keyword(s):  
Spectral Analysis ◽  
Stellar Evolution ◽  
Surface Composition ◽  
Planetary Nebulae ◽  
Asymptotic Giant Branch ◽  
Thermodynamical Equilibrium ◽  
Non Local ◽  
Rich Material ◽  
Stellar Masses ◽  
Central Stars

Abstract Stellar post asymptotic giant branch (post-AGB) evolution can be completely altered by a final thermal pulse (FTP) which may occur when the star is still leaving the AGB (AFTP), at the departure from the AGB at still constant luminosity (late TP, LTP) or after the entry to the white-dwarf cooling sequence (very late TP, VLTP). Then convection mixes the He-rich material with the H-rich envelope. According to stellar evolution models the result is a star with a surface composition of $\mathrm{H}\approx \, 20$ per cent by mass (AFTP), ≈ 1 per cent (LTP), or (almost) no H (VLTP). Since FTP stars exhibit intershell material at their surface, spectral analyses establish constraints for AGB nucleosynthesis and stellar evolution. We performed a spectral analysis of the so-called hybrid PG 1159-type central stars (CS) of the planetary nebulae Abell 43 and NGC 7094 by means of non-local thermodynamical equilibrium models. We confirm the previously determined effective temperatures of $\mbox{$T_\mathrm{eff}$}\, = 115\, 000\pm 5\, 000 \, \mathrm{K}$ and determine surface gravities of $\log\,(g\,/\,(\mathrm{cm}\,\mathrm{s}^{-2} )) = 5.6\pm 0.1$ for both. From a comparison with AFTP evolutionary tracks, we derive stellar masses of $0.57^{+0.07}_{-0.04}$ M⊙ and determine the abundances of H, He, and metals up to Xe. Both CS are likely AFTP stars with a surface H mass fraction of 0.25 ± 0.03 and 0.15 ± 0.03, respectively, and an Fe deficiency indicating subsolar initial metallicities. The light metals show typical PG 1159-type abundances and the elemental composition is in good agreement with predictions from AFTP evolutionary models. However, the expansion ages do not agree with evolution time-scales expected from the AFTP scenario and alternatives should be explored.

scholarly journals Planetary Nebula Evolution Traced by Distance-Independent Parameters

1993 ◽  
Vol 155 ◽  
pp. 480-480
Author(s):  
C.Y. Zhang ◽  
S. Kwok
Keyword(s):  
Physical Properties ◽  
Mass Distribution ◽  
Planetary Nebula ◽  
Strong Support ◽  
Planetary Nebulae ◽  
Central Star ◽  
Evolution Model ◽  
The Core ◽  
Independent Parameters ◽  
Central Stars

Making use of the results from recent infrared and radio surveys of planetary nebulae, we have selected 431 nebulae to form a sample where a number of distance-independent parameters (e.g., Tb, Td, I60μm and IRE) can be constructed. In addition, we also made use of other distance-independent parameters ne and T∗ where recent measurements are available. We have investigated the relationships among these parameters in the context of a coupled evolution model of the nebula and the central star. We find that most of the observed data in fact lie within the area covered by the model tracks, therefore lending strong support to the correctness of the model. Most interestingly, we find that the evolutionary tracks for nebulae with central stars of different core masses can be separated in a Tb-T∗ plane. This implies that the core masses and ages of the central stars can be determined completely independent of distance assumptions. The core masses and ages have been obtained for 302 central stars with previously determined central-star temperatures. We find that the mass distribution of the central stars strongly peaks at 0.6 M⊙, with 66% of the sample having masses <0.64 MM⊙. The luminosities of the central stars are then derived from their positions in the HR diagram according to their core masses and central star temperatures. If this method of mass (and luminosity) determination turns out to be accurate, we can bypass the extremely unreliable estimates for distances, and will be able to derive other physical properties of planetary nebulae.

Sign in / Sign up

Export Citation Format

Share Document