scholarly journals Planetary Nebulae and Wolf-Rayet Nebulae

2003 ◽  
Vol 209 ◽  
pp. 193-200 ◽  
Author(s):  
Y. Grosdidier
Keyword(s):  
Mass Loss ◽  
Planetary Nebula ◽  
Planetary Nebulae ◽  
Stellar Mass ◽  
Stellar Atmospheres ◽  
Similarities And Differences ◽  
Wr Nebulae

In the present paper I review some important facts regarding the similarities and differences between Galactic planetary nebulae and Galactic Wolf-Rayet (WR) nebulae within the scope of stellar mass-loss history and its subsequent impact on the nebular dynamics and morphology. The case of planetary nebulae with [WR] nuclei, which allows one to perform a more direct comparison with WR nebulae, is emphasized. In particular, I describe the apparently ubiquitous turbulent-like phenomena originating in [WR] stellar atmospheres and the surrounding nebulae, and discuss the possible impact of turbulence on planetary nebula studies.

scholarly journals Thermal Pulses and Planetary Nebula Ejection

1993 ◽  
Vol 155 ◽  
pp. 291-298 ◽  
Author(s):  
P.R. Wood ◽  
E. Vassiliadis
Keyword(s):  
Mass Loss ◽  
Planetary Nebula ◽  
Planetary Nebulae ◽  
Stellar Surface ◽  
Agb Stars ◽  
Theoretical Evolution ◽  
Thermal Pulses

Thermal pulses in AGB stars cause large luminosity variations at the stellar surface. The role of these luminosity variations in the production of planetary nebulae is discussed. Results of theoretical evolution calculations which include mass loss modulated by thermal pulses are presented.

scholarly journals Central Stars of Young Planetary Nebulae - A New Class of Variables

2003 ◽  
Vol 209 ◽  
pp. 237-238 ◽  
Author(s):  
G. Handler
Keyword(s):  
Mass Loss ◽  
Radial Velocity ◽  
Time Scales ◽  
Variable Star ◽  
Planetary Nebulae ◽  
Stellar Mass ◽  
New Class ◽  
Stellar Pulsation ◽  
Stellar Pulsations ◽  
Central Stars

A new class of variable star is proposed. These are variable central stars of young Planetary Nebulae exhibiting roughly sinusoidal (semi)regular photometric and/or radial velocity variations with time scales of several hours. Fourteen of these objects have been identified. Their temperatures are between 25000 and 50000 K and most show hydrogen-rich spectra. The most likely reason for the variability is stellar pulsation. Another possibility would be variable stellar mass loss, but in that case the mechansism causing it must be different from that operating in massive O stars. We speculate that it actually is the stellar pulsations which cause mass loss mdulations.

scholarly journals Stellar wind models of central stars of planetary nebulae

2020 ◽  
Vol 635 ◽  
pp. A173 ◽  
Author(s):  
J. Krtička ◽  
J. Kubát ◽  
I. Krtičková
Keyword(s):  
Mass Loss ◽  
White Dwarf ◽  
Planetary Nebula ◽  
Loss Rate ◽  
Mass Loss Rate ◽  
Planetary Nebulae ◽  
Terminal Velocity ◽  
Asymptotic Giant Branch ◽  
Central Stars ◽  
Loss Rates

Context. Fast line-driven stellar winds play an important role in the evolution of planetary nebulae, even though they are relatively weak. Aims. We provide global (unified) hot star wind models of central stars of planetary nebulae. The models predict wind structure including the mass-loss rates, terminal velocities, and emergent fluxes from basic stellar parameters. Methods. We applied our wind code for parameters corresponding to evolutionary stages between the asymptotic giant branch and white dwarf phases for a star with a final mass of 0.569 M⊙. We study the influence of metallicity and wind inhomogeneities (clumping) on the wind properties. Results. Line-driven winds appear very early after the star leaves the asymptotic giant branch (at the latest for Teff ≈ 10 kK) and fade away at the white dwarf cooling track (below Teff = 105 kK). Their mass-loss rate mostly scales with the stellar luminosity and, consequently, the mass-loss rate only varies slightly during the transition from the red to the blue part of the Hertzsprung–Russell diagram. There are the following two exceptions to the monotonic behavior: a bistability jump at around 20 kK, where the mass-loss rate decreases by a factor of a few (during evolution) due to a change in iron ionization, and an additional maximum at about Teff = 40−50 kK. On the other hand, the terminal velocity increases from about a few hundreds of km s−1 to a few thousands of km s−1 during the transition as a result of stellar radius decrease. The wind terminal velocity also significantly increases at the bistability jump. Derived wind parameters reasonably agree with observations. The effect of clumping is stronger at the hot side of the bistability jump than at the cool side. Conclusions. Derived fits to wind parameters can be used in evolutionary models and in studies of planetary nebula formation. A predicted bistability jump in mass-loss rates can cause the appearance of an additional shell of planetary nebula.

scholarly journals Stellar masers, circumstellar envelopes and supernova remnants

2007 ◽  
Vol 3 (S242) ◽  
pp. 236-245
Author(s):  
Athol J. Kemball
Keyword(s):  
Mass Loss ◽  
Stellar Evolution ◽  
Supernova Remnants ◽  
Stellar Mass ◽  
Stellar Atmospheres ◽  
Late Type ◽  
Open Future ◽  
Circumstellar Envelopes ◽  
Recent Advances

AbstractThis paper reviews recent advances in the study or circumstellar masers and masers found toward supernova remnants. The review is organized by science focus area, including the astrophysics of extended stellar atmospheres, stellar mass-loss processes and outflows, late-type evolved stellar evolution, stellar maser excitation and chemistry, and the use of stellar masers as independent distance estimators. Masers toward supernova remnants are covered separately. Recent advances and open future questions in this field are explored.

scholarly journals Structure and Evolution of Planetary Nebula Haloes

2003 ◽  
Vol 209 ◽  
pp. 439-446 ◽  
Author(s):  
Matthias Steffen ◽  
Detlef Schönberner
Keyword(s):  
Mass Loss ◽  
Numerical Simulations ◽  
Stellar Evolution ◽  
Planetary Nebula ◽  
Previous History ◽  
Planetary Nebulae ◽  
Asymptotic Giant Branch ◽  
Time Dependent ◽  
Density Structure ◽  
History Of

The density structure of the extended haloes of Planetary Nebulae (PN) is generally believed to reflect the previous history of heavy mass loss during the final stages of stellar evolution on the asymptotic giant-branch (AGB). In this review, we discuss different interpretations of the observed PN halo structures in the light of recent numerical simulations combining detailed AGB and post-AGB stellar evolution calculations with time-dependent hydrodynamical wind models.

scholarly journals On the triple-star origin of the planetary nebula Sh 2-71

2019 ◽  
Vol 489 (2) ◽  
pp. 2195-2203 ◽  
Author(s):  
David Jones ◽  
Ondřej Pejcha ◽  
Romano L M Corradi
Keyword(s):  
Mass Loss ◽  
Triple System ◽  
Planetary Nebula ◽  
Planetary Nebulae ◽  
Central Star ◽  
Radial Velocities ◽  
Proper Motions ◽  
Numerical Integrations ◽  
Open Questions ◽  
Triple Star

ABSTRACT Recent studies have indicated that triple-star systems may play a role in the formation of an appreciable number of planetary nebulae, however, only one triple central star is known to date (and that system is likely too wide to have had much influence on the evolution of its component stars). Here, we consider the possibility that Sh 2-71 was formed by a triple system that has since broken apart. We present the discovery of two regions of emission, seemingly aligned with the proposed tertiary orbit (i.e. in line with the axis formed by the two candidate central star systems previously considered in the literature). We also perform a few simple tests of the plausibility of the triple hypothesis based on the observed properties (coordinates, radial velocities, distances, and proper motions) of the stars observed close to the projected centre of the nebula, adding further support through numerical integrations of binary orbits responding to mass loss. Although a number of open questions remain, we conclude that Sh 2-71 is currently one of the best candidates for planetary nebula formation influenced by triple-star interactions.

scholarly journals The initial/final mass relation for stellar evolution with mass loss

1981 ◽  
Vol 59 ◽  
pp. 339-344
Author(s):  
Volker Weidemann
Keyword(s):  
Mass Loss ◽  
Stellar Evolution ◽  
White Dwarf ◽  
Empirical Data ◽  
Planetary Nebula ◽  
White Dwarfs ◽  
Planetary Nebulae ◽  
Universal Relation ◽  
Mass Relation ◽  
Theoretical Concepts

The relation between initial and final masses is discussed under consideration of changing theoretical concepts and new empirical data on masses of white dwarfs and nuclei of planetary nebulae. It is concluded that presently adopted schemes of evolution need revision, and that no universal relation exists.The strongest evidence for large amounts of mass loss during stellar evolution has been provided by the existence of white dwarfs – with masses typically of 0.6 m (m = M/Mʘ), much below the galactic turn-off masses – and by the phenomenon of planetary nebula production before a star descends into the white dwarf region.

scholarly journals Formation and Evolution of Planetary Nebulae: A Radiation Hydrodynamics Study

2003 ◽  
Vol 209 ◽  
pp. 157-158
Author(s):  
M. Perinotto ◽  
C. Calonaci ◽  
D. Schönberner ◽  
M. Steffen ◽  
T. Blöcker
Keyword(s):  
Mass Loss ◽  
Wind Power ◽  
Planetary Nebula ◽  
Rapid Evolution ◽  
Planetary Nebulae ◽  
Central Star ◽  
Radiation Hydrodynamics ◽  
Formation And Evolution

The formation and evolution of a planetary nebula is based on the occurrence of a strong AGB wind and the rapid evolution of the central star with corresponding changes of its ionizing flux and wind power. We have studied the influence of different mass-loss histories in combination with various central-star properties.

scholarly journals Mass loss from central stars of planetary nebulae

1981 ◽  
Vol 59 ◽  
pp. 45-50
Author(s):  
Mario Perinotto ◽  
Piero Benvenuti ◽  
Carla Cacciari
Keyword(s):  
Mass Loss ◽  
Planetary Nebula ◽  
Loss Rate ◽  
Mass Loss Rate ◽  
Planetary Nebulae ◽  
Central Star ◽  
High Resolution Spectrum ◽  
Preliminary Evaluation ◽  
Associated Mass ◽  
Central Stars

AbstractFrom a high resolution spectrum taken with IUE, the central star of the planetary nebula IC 2149 is found to exibit a wind with edge velocity of 1440 ± 100 km s-1. Our preliminary evaluation of the associated mass loss rate gives 10-8 M0 yr-1. Other planetary nebulae nuclei are studied with low resolution IUE spectra and indications are found of mass loss rates consistent with the above value.

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