scholarly journals Kinematics of Disk Planetary Nebulae

1993 ◽  
Vol 155 ◽  
pp. 568-568
Author(s):  
W.J. Maciel ◽  
C.M. Dutra
Keyword(s):  
Chemical Composition ◽  
Stellar Evolution ◽  
Classification Scheme ◽  
Planetary Nebulae ◽  
The Past

In the past few years, it has become clear that planetary nebulae (PN) are a true stage in stellar evolution, especially regarding their chemical composition. This fact led to the introduction of the classification scheme developed by Peimbert, which has been applied to a sample of galactic objects for which a detailed amount of data exists.

scholarly journals Kinematic and chemical analysis of PNe in NGC 3109

2016 ◽  
Vol 12 (S323) ◽  
pp. 390-391
Author(s):  
Sheila N. Flores-Dúran ◽  
Miriam Peña ◽  
María T. Ruiz
Keyword(s):  
Chemical Composition ◽  
High Resolution ◽  
Chemical Analysis ◽  
Stellar Evolution ◽  
Planetary Nebulae ◽  
High Resolution Spectroscopy ◽  
Irregular Galaxy ◽  
The One

AbstractWe present high resolution spectroscopy obtained with MIKE-Magellan and MES OAN-SPM of a number of planetary nebulae (PNe) and H ii regions, distributed along the dwarf irregular galaxy NGC 3109 and compare their kinematical behavior with the one of H i data. We aim to determine if there is a kinematical connection among these objects. We also perform a revision of the chemical composition of PNe and H ii regions in this galaxy and discuss it in comparison with stellar evolution models.

scholarly journals Asymptotic giant branch evolution: Where do we stand?

2011 ◽  
Vol 7 (S283) ◽  
pp. 87-94 ◽  
Author(s):  
Paola Marigo
Keyword(s):  
Chemical Composition ◽  
Stellar Evolution ◽  
Present Status ◽  
Recent Progress ◽  
Planetary Nebulae ◽  
Asymptotic Giant Branch ◽  
Future Perspectives ◽  
Stellar Models

AbstractI provide a synthetic overview of the present status of stellar models for the asymptotic giant branch phase, one of the most complex and still uncertain stages of stellar evolution. In particular I will focus on two aspects that are most relevant in the context of the planetary nebulæ progeny, namely: the chemical composition of the AGB ejecta, and the mass of the bare CO core left after the ejection of the stellar mantle at the AGB tip. Recent progress, present uncertainties, and future perspectives to constrain AGB models are briefly discussed.

scholarly journals Formation rates of AGB stars and Planetary Nebulae

1997 ◽  
Vol 180 ◽  
pp. 411-411
Author(s):  
R. Ortiz ◽  
W. J. Maciel
Keyword(s):  
Stellar Evolution ◽  
Classification Scheme ◽  
Local Population ◽  
Planetary Nebulae ◽  
Type I ◽  
Agb Stars ◽  
Death Rates ◽  
Thermal Pulse ◽  
Adopted Model ◽  
Good Agreement

We study the local population of AGB stars, and determine their densities and scale heights according to their masses, following the classification scheme proposed by Ortiz and Maciel (1994, A&A 287, 552), which discriminates the precursors of type I, II, and III planetary nebulae. The formation (or death) rates of AGB stars are determined by means of stellar evolution models, and are compared to the formation rates of planetary nebulae from the literature. A good agreement is found between these rates; however, the results are very sensitive to the adopted model, especially regarding the time spent at the thermal-pulse AGB phase.(FAPESP, CNPq)

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 Pre-White Dwarf Evolution Through Planetary Nebulae

1991 ◽  
Vol 145 ◽  
pp. 399-409
Author(s):  
Francesca D'antona ◽  
Italo Mazzitelli
Keyword(s):  
Chemical Composition ◽  
Stellar Evolution ◽  
White Dwarf ◽  
Total Mass ◽  
White Dwarfs ◽  
Planetary Nebulae ◽  
Asymptotic Giant Branch ◽  
Present Review ◽  
Stellar Models ◽  
Thermal Pulses

In the present review we summarize the problems relative to the chemical composition of the inner and outer layers of white dwarfs as expected from stellar evolution. We point out that there is a contrast between standard predictions and the indications deriving from studies of white dwarfs, as “massive” hydrogen remnat layers seem not to be present on single white dwarfs. We discuss a previously neglected feature of stellar models in the phase of thermal pulses -which occurs when the outer hydrogen envelope becomes very small- by which the progenitors of low total mass may get rid of practically the whole hydrogen envelope during the final phases of asymptotic giant branch evolution. We finally propose a new global scheme for the pre-white dwarf evolution, which depends mainly on the initial progenitor mass.

The Evolution of the Nuclei of Planetary Nebulae

1972 ◽  
Vol 2 (2) ◽  
pp. 72-78
Author(s):  
D. J. Faulkner
Keyword(s):  
Stellar Evolution ◽  
Time Scale ◽  
Planetary Nebulae ◽  
Considerable Importance ◽  
Stellar Objects ◽  
The Past ◽  
Low Mass

In the past decade, planetary nebulae have assumed considerable importance in elucidating our understanding of the final stages of stellar evolution at low mass. This began with the work of Shklovsky, O’Dell and Seaton, who showed not only that the nuclei of these nebulae were among the hottest stellar objects, but also that they evolved on a track in the Hertzsprung-Russell diagram (the Harman-Seaton sequence) on a time scale very rapid by stellar evolutionary standards (~ 20,000 years).

Stellar Evolution

1962 ◽  
Vol 11 (02) ◽  
pp. 137-143
Author(s):  
M. Schwarzschild
Keyword(s):  
Solar System ◽  
Stellar Evolution ◽  
Space Craft ◽  
New Techniques ◽  
Substantial Body ◽  
Individual Stars ◽  
The Past ◽  
Evolution Of Galaxies ◽  
History Of ◽  
Fast Flow

It is perhaps one of the most important characteristics of the past decade in astronomy that the evolution of some major classes of astronomical objects has become accessible to detailed research. The theory of the evolution of individual stars has developed into a substantial body of quantitative investigations. The evolution of galaxies, particularly of our own, has clearly become a subject for serious research. Even the history of the solar system, this close-by intriguing puzzle, may soon make the transition from being a subject of speculation to being a subject of detailed study in view of the fast flow of new data obtained with new techniques, including space-craft.

scholarly journals New models for the rapid evolution of the central star of the Stingray Nebula

2021 ◽  
Author(s):  
T M Lawlor
Keyword(s):  
Mass Loss ◽  
Stellar Evolution ◽  
Planetary Nebula ◽  
Rapid Evolution ◽  
Central Star ◽  
Asymptotic Giant Branch ◽  
Initial Mass ◽  
Thermal Pulse ◽  
The Past ◽  
New Models

Abstract We present stellar evolution calculations from the Asymptotic Giant Branch (AGB) to the Planetary Nebula (PN) phase for models of initial mass 1.2 M⊙ and 2.0 M⊙ that experience a Late Thermal Pulse (LTP), a helium shell flash that occurs following the AGB and causes a rapid looping evolution between the AGB and PN phase. We use these models to make comparisons to the central star of the Stingray Nebula, V839 Ara (SAO 244567). The central star has been observed to be rapidly evolving (heating) over the last 50 to 60 years and rapidly dimming over the past 20–30 years. It has been reported to belong to the youngest known planetary nebula, now rapidly fading in brightness. In this paper we show that the observed timescales, sudden dimming, and increasing Log(g), can all be explained by LTP models of a specific variety. We provide a possible explanation for the nebular ionization, the 1980’s sudden mass loss episode, the sudden decline in mass loss, and the nebular recombination and fading.

scholarly journals ​Chemistry, Nutritional Properties and Application of Mare’s Milk: A Review

2021 ◽  
Author(s):  
Shaikh Adil ◽  
B.M. Mehta ◽  
Atanu H. Jana
Keyword(s):  
Chemical Composition ◽  
Soviet Union ◽  
Former Soviet Union ◽  
Nutritional Value ◽  
Mammal Species ◽  
Nutritional Properties ◽  
Southern States ◽  
The Past ◽  
Health Promoting ◽  
Therapeutic Properties

Mare’s milk has long been considered to have special nutritive and therapeutic properties in Mongolia and southern states of the former Soviet Union. It is now gaining popularity in some parts in Europe also. Mares’ milk is characterized by their unique nutritional profile. Therefore, interest has increased in the use of mare’s milk for human nutrition in the past several years, especially in France and Germany. As compared to many other mammal species, mare’s milk is highly appreciated for similarity to human milk in terms of chemical composition allowing its use as a substitute for mother’s milk in infant feeding. Mare’s milk also has been used for the treatment of certain human pathologies such as hepatitis, chronic ulcer and tuberculosis. This review dwells on the chemical composition, nutritional value and various health-promoting properties of mare’s milk.

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