OH/IR Stars and other IRAS Point Sources as Progenitors of Planetary Nebulae

1989 ◽  
Vol 131 ◽  
pp. 359-380 ◽  
Author(s):  
H. J. Habing ◽  
P. te Lintel Hekkert ◽  
W.E.C.J. van der Veen
Keyword(s):  
Planetary Nebulae ◽  
Point Sources ◽  
Agb Stars ◽  
Evolutionary Sequence ◽  
Centre Of Mass ◽  
Long Period ◽  
Mira Variables ◽  
Ir Stars ◽  
Galactic Population ◽  
History Of

We briefly review the history of the search for progenitors of planetary nebulae starting with Shklovsky's (1956) paper. The inner structure of AGB stars (the likely progenitors) is sketched. The (l, b) distributions and the (l, V) distributions (V is the centre of mass radial velocity) of OH/IR stars and of planetary nebulae are compared; it is concluded that, grosso modo, both types of objects belong to the same galactic population and that most OH/IR stars develop ultimately into planetary nebulae. From a comparison of the properties of OH/IR stars and of Mira variables it is concluded that both are AGB stars with the OH/IR stars having developed from Mira variables. Most OH/IR stars are long period variables but the few that are not are probably transition cases -no longer AGB stars and very early planetary nebulae. It is argued that the IRAS catalog contains a large number of AGB stars without (detected) OH maser emission, but otherwise similar to OH/IR stars. An evolutionary sequence is presented from Mira's to oxygen-rich planetary nebulae. Some speculations are added on the formation of carbon stars and carbon-rich planetary nebulae.

scholarly journals Born-again AGB stars: Starting point of the H-deficient post-AGB evolutionary sequence?

1999 ◽  
Vol 191 ◽  
pp. 493-498 ◽  
Author(s):  
K. Werner ◽  
S. Dreizler ◽  
T. Rauch ◽  
L. Koesterke ◽  
U. Heber
Keyword(s):  
Planetary Nebulae ◽  
Agb Stars ◽  
Evolutionary Sequence ◽  
Starting Point ◽  
Born Again

We discuss the origin of hot hydrogen-deficient post-AGB stars. Evidence is growing that the “born-again AGB star scenario” as a consequence of a late He shell flash cannot explain the diverse observations. Analyses of the stars and their associated planetary nebulae suggest that the H-deficiency is not formed during the second post-AGB phase but already while the star is still on the AGB. There are even hints that the H-deficiency can occur before the first departure from the AGB.

scholarly journals Spectral analysis of the O(He)-type central stars of the planetary nebulae K 1-27 and LoTr 4

2011 ◽  
Vol 7 (S283) ◽  
pp. 482-483
Author(s):  
Nicole Reindl ◽  
Ellen Ringat ◽  
Thomas Rauch ◽  
Klaus Werner ◽  
Jeffrey. W. Kruk
Keyword(s):  
Spectral Analysis ◽  
Planetary Nebulae ◽  
Agb Stars ◽  
Evolutionary Sequence ◽  
Preliminary Results ◽  
Pure Helium ◽  
R Coronae Borealis Stars ◽  
Central Stars

AbstractThe four known O(He) stars are the only amongst the hottest post-AGB stars whose atmospheres are composed of almost pure helium. Thus, their evolution deviates from the hydrogen-deficient post-AGB evolutionary sequence of carbon-dominated stars like e.g. PG 1159 stars. The origin of the O(He) stars is still not explained. They might be either post-early AGB stars or the progeny of R Coronae Borealis stars. We present preliminary results of a non-LTE spectral analysis based on FUSE and HST/COS observations.

New OH/IR Stars: Proto-Planetary Nebulae?

1989 ◽  
Vol 131 ◽  
pp. 448-448
Author(s):  
J. Eder ◽  
B. M. Lewis ◽  
Yervant Terzian
Keyword(s):  
Planetary Nebulae ◽  
Point Sources ◽  
Type Ii ◽  
Ir Stars ◽  
First Time ◽  
Right Ascension

The IRAS infrared colors, (60 - 25)μm and (25 - 12)μm, allow efficient identification of Type II OE/IR stars. We present Arecibo1 OH (1612 MHz) observations of 474 IRAS point sources chosen to define the exact regions of the two-color diagram occupied by OH/IR stars. Our observations are complete within the boundary regions of the two-color locus and within the region, 16h right ascension < 22h, 0° < declination < 37°. The sensitivity of the Arecibo telescope allows the identification of many weak sources that would not have been detected by previous surveys and the weak end of the masing phenomenon has been studied for the first time.

OH/IR Stars and Other IRAS Point Sources as Progenitors of Planetary Nebulae

1989 ◽  
pp. 359-380 ◽  
Author(s):  
H. J. Habing ◽  
P. te Lintel Hekkert ◽  
W. E. C. J. van der Veen
Keyword(s):  
Planetary Nebulae ◽  
Point Sources ◽  
Ir Stars

scholarly journals Common Envelope Evolution: Implications for Post-AGB Stars and Planetary Nebulae

2016 ◽  
Vol 12 (S323) ◽  
pp. 207-212 ◽  
Author(s):  
J. Nordhaus
Keyword(s):  
Planetary Nebula ◽  
Planetary Nebulae ◽  
Agb Stars ◽  
Common Envelope ◽  
Long Period ◽  
Short Period ◽  
Computational Work ◽  
Broad Interest

AbstractCommon envelopes (CE) are of broad interest as they represent one method by which binaries with initially long-period orbits of a few years can be converted into short-period orbits of a few hours. Despite their importance, the brief lifetimes of CE phases make them difficult to directly observe. Nevertheless, CE interactions are potentially common, can produce a diverse array of nebular shapes, and can accommodate current post-AGB and planetary nebula outflow constraints. Here, I discuss ongoing theoretical and computational work on CEs and speculate on what lies ahead for determining accurate outcomes of this elusive phase of evolution.

scholarly journals AGB stars and galactic dynamics

1999 ◽  
Vol 191 ◽  
pp. 500-510 ◽  
Author(s):  
H. Dejonghe ◽  
K. Van Caelenberg
Keyword(s):  
Chemical Composition ◽  
Stellar Population ◽  
Milky Way ◽  
Planetary Nebulae ◽  
Line Of Sight ◽  
Galactic Dynamics ◽  
Stellar Systems ◽  
Agb Stars ◽  
Dynamical Models ◽  
Ir Stars

AGB stars, seen as a stellar population, can be used to probe the dynamical state of galaxies. The relevant data are mostly positions and line-of-sight velocities, sometimes together with information on chemical composition and/or age. As of now, dynamical models have been made for OH/IR stars and Planetary Nebulae. Other candidates are C stars, S stars, and Miras. We review the methods used and the results obtained so far, for the Milky Way and for (relatively nearby) extragalactic stellar systems.

scholarly journals CO in OH/IR-Stars - on Excitation and Mass Loss

1989 ◽  
Vol 106 ◽  
pp. 368-368
Author(s):  
A. Heske ◽  
H.J. Habing ◽  
W.E.C.J. van der Veen ◽  
A. Omont ◽  
T. Forveille
Keyword(s):  
Mass Loss ◽  
Agb Stars ◽  
Line Formation ◽  
Circumstellar Envelopes ◽  
Simple Method ◽  
Long Period ◽  
Ir Stars ◽  
Low Mass ◽  
The Impact ◽  
Loss Rates

Observations of CO in long period variables have been widely used to determine mass loss rates by applying models for CO line formation (e.g. Knapp and Morris, 1985) which use a simple method to take the impact from infrared radiation into account. Recent 00(2-1) and (1-0) observations of some more evolved OH/IR stars yielded much too low mass loss rates using these simple models, thus indicating that they cannot be extrapolated to far evolved AGB stars with optically thick circumstellar envelopes.

scholarly journals Dynamics of Agb Stars and Planetary Nebulae in the Galaxy

1993 ◽  
Vol 155 ◽  
pp. 541-548
Author(s):  
H. Dejonghe
Keyword(s):  
Planetary Nebulae ◽  
Agb Stars ◽  
Dynamical Models ◽  
Ir Stars ◽  
The Galaxy ◽  
Kinematical Data

The available kinematical data on OH/IR stars and PNs are reviewed. Dynamical models for the OH/IR stars are presented.

scholarly journals Deduction of Planetary Nebulae Properties from Long Period Variable Precursors

1983 ◽  
Vol 103 ◽  
pp. 291-291
Author(s):  
M. S. Bessell ◽  
P. R. Wood
Keyword(s):  
Planetary Nebula ◽  
Mass Spectra ◽  
Planetary Nebulae ◽  
Magellanic Clouds ◽  
Asymptotic Giant Branch ◽  
Agb Stars ◽  
Long Period ◽  
Period Variable ◽  
Low Mass ◽  
Nucleus Mass

Infra-red (JHK) photometry of long period variables (LPV) in the Magellanic Clouds has shown that the LPV's can be divided into core helium burning supergiants and asymptotic giant branch (AGB) stars. Application of the pulsation theory allows masses to be derived for the LPV's while stellar evolution theory allows core masses to be derived for the AGB stars. By considering evolution of the LPV's in the (Mbol,P) diagram, estimates of planetary nebula mass and planetary nebula nucleus mass are derived as a function of initial mass. Spectra of the LPV's suggest that many low mass planetary nebulae in the Magellanic Clouds should be carbon rich while the more massive nebulae may be nitrogen enhanced.

scholarly journals Chemical Enrichment and Central Star Properties

1993 ◽  
Vol 155 ◽  
pp. 572-572
Author(s):  
C.Y. Zhang
Keyword(s):  
Planetary Nebulae ◽  
Central Star ◽  
Agb Stars ◽  
Physical Processes ◽  
Chemical Abundances ◽  
Core Mass ◽  
Chemical Enrichment ◽  
The Core ◽  
Stellar Temperature ◽  
Independent Parameters

We have selected a sample of planetary nebulae, for which the core masses are determined using distance-independent parameters (Zhang and Kwok 1992). The chemical abundances of He, N, O, and C are taken from the literature for them. Relationships of the ratios of He/H, N/O, and C/O with various stellar parameters of planetary nebulae (PN), such as the core mass, the mass of the core plus the ionized nebular gas, the stellar age and temperature, are examined. It is found that the N/O increases with increasing mass, while the C/O first increases and then decreases with the core mass. No strong correlation seems to exist between the He/H and the core mass. A correlation of the N/O and He/H with the stellar temperature exists. The current dredge-up theory for the progenitor AGB stars cannot satisfactorily account for these patterns of chemical enrichment in PN. Furthermore, the correlations of the N/O and He/H with the stellar age and temperature indicate that besides the dredge-ups in the RG and AGB stages, physical processes that happen in the planetary nebula stage may also play a role in forming the observed patterns of chemical enrichment in the planetary nebulae.

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