Low-mass stars. I - Flash-driven luminosity and radius variations. II - The core mass-luminosity relations. III - Low-mass stars with steady mass loss - Up to the asymptotic giant branch and through the final thermal pulses

1988 ◽  
Vol 328 ◽  
pp. 632 ◽  
Author(s):  
Arnold I. Boothroyd ◽  
I.-Juliana Sackmann
Keyword(s):  
Mass Loss ◽  
Asymptotic Giant Branch ◽  
Low Mass Stars ◽  
Core Mass ◽  
The Core ◽  
Low Mass ◽  
Thermal Pulses

Low-Mass Stars. III. Low-Mass Stars with Steady Mass Loss: Up to the Asymptotic Giant Branch and through the Final Thermal Pulses

1988 ◽  
Vol 328 ◽  
pp. 653 ◽  
Author(s):  
Arnold I. Boothroyd ◽  
I.-Juliana Sackmann
Keyword(s):  
Mass Loss ◽  
Asymptotic Giant Branch ◽  
Low Mass Stars ◽  
Low Mass ◽  
Thermal Pulses

scholarly journals Parameterising the Third Dredge-up in Asymptotic Giant Branch Stars

2002 ◽  
Vol 19 (4) ◽  
pp. 515-526 ◽  
Author(s):  
A. I. Karakas ◽  
J. C. Lattanzio ◽  
O. R. Pols
Keyword(s):  
Mass Loss ◽  
Asymptotic Giant Branch ◽  
Asymptotic Giant Branch Stars ◽  
Core Mass ◽  
The Third ◽  
The Core ◽  
Intermediate Mass Stars ◽  
Homogeneous Set ◽  
Efficiency Parameter ◽  
Giant Branch Stars

AbstractWe present new evolutionary sequences for low and intermediate mass stars (1−6M⊙) for three different metallicities, Z = 0.02, 0.008, and 0.004. We evolve the models from the pre-main sequence to the thermally-pulsing asymptotic giant branch phase. We have two sequences of models for each mass, one which includes mass loss and one without mass loss. Typically 20 or more pulses have been followed for each model, allowing us to calculate the third dredge-up parameter for each case. Using the results from this large and homogeneous set of models, we present an approximate fit for the core mass at the first thermal pulse, Mc1, as well as for the third dredge-up efficiency parameter, λ, and the core mass at the first dredge-up episode, Mcmin, as a function of metallicity and total mass. We also examine the effect of a reduced envelope mass on the value of λ.

scholarly journals The Effect of Coulomb Interactions on the Helium Flash

1989 ◽  
Vol 114 ◽  
pp. 81-84
Author(s):  
A. Harpaz ◽  
A. Kovetz
Keyword(s):  
Mass Loss ◽  
Charged Particles ◽  
Red Giants ◽  
Coulomb Interactions ◽  
Core Mass ◽  
The Core ◽  
Low Mass ◽  
Red Giant ◽  
Recent Claim

AbstractDetailed evolutionary calculations show that Coulomb interactions between the charged particles of a stellar plasma reduce the core mass at which a low mass red giant undergoes the helium flash (contrary to a recent claim). This has implications for the determination of the rate of mass loss from red giants.

scholarly journals New Calculations of Thermal Pulses and s–Process Nucleosynthesis in Agb Stars

1993 ◽  
Vol 155 ◽  
pp. 361-361
Author(s):  
M. Busso ◽  
A. Chieffi ◽  
R. Gallino ◽  
M. Limongi ◽  
C. M. Raiteri ◽  
...  
Keyword(s):  
Mass Loss ◽  
Agb Stars ◽  
Evolutionary Track ◽  
Core Mass ◽  
Shell Mass ◽  
The Third ◽  
The Core ◽  
Solar Metallicity ◽  
Stellar Masses ◽  
Thermal Pulses

A set of thermal pulse models was computed, for initial stellar masses extending from low (M=1.5, 3 M⊙) to intermediate (M=5, 7 M⊙), using the FRANEC evolutionary code and assuming standard mass loss and solar metallicity. The main features are: i) the third dredge–up is naturally found, even for core masses below 0.7–0.8 M⊙; ii) before the dredge–up occurrence, the main characteristics of the models (convective shell mass, interpulse duration, overlapping between adjacent pulses) are determined solely by the core mass MH, well reproducing a behaviour which is typical in the current literature (see e.g. Schonberner, 1979): in particular, the shell mass is a decreasing function of MH; iii) after dredge–up is started, the evolutionary track is modified and the strength of the pulses is enhanced; iv) the amount of dredge–up increases in time, from ≃ 10−4 M⊙ to ≃ 10−3 M⊙.

Low-Mass Stars. II. The Core Mass--Luminosity Relations for Low-Mass Stars

1988 ◽  
Vol 328 ◽  
pp. 641 ◽  
Author(s):  
Arnold I. Boothroyd ◽  
I.-Juliana Sackmann
Keyword(s):  
Low Mass Stars ◽  
Core Mass ◽  
The Core ◽  
Low Mass

scholarly journals On Low Mass AGB Stars

1991 ◽  
Vol 145 ◽  
pp. 275-285 ◽  
Author(s):  
I.-Juliana Sackmann ◽  
Arnold I. Boothroyd
Keyword(s):  
Mass Loss ◽  
Narrow Range ◽  
Carbon Star ◽  
Theoretical Models ◽  
Initial Mass ◽  
Mixing Length ◽  
Agb Stars ◽  
Low Mass Stars ◽  
Low Mass ◽  
Thermal Pulses

Recent results on low mass AGB stars are presented. Observed amounts of AGB mass loss imply that thermal pulses will only be encountered for stars of initial mass less than about 4M⊙ for Pop I and 3 M⊙ for Pop II. Mc – L, Me – τif, and Mc – Tb relations are summarized. Carbon dredge-up has been found in low mass stars of both Pop I and Pop II; the mixing length parameter α is crucial to dredge-up, and its value must be normalized according to each author's opacities and mixing length treatment (e.g., via the Sun's Te and L). The “carbon star mystery” is nearing a solution, but a new “s-process mystery” has appeared: only in a narrow range of mass and metallicity have theoretical models been found that encounter the semiconvective 13C s-process mechanism.

scholarly journals Low-Mass AGB Stellar Models for 0.003 ≤ Z ≤ 0.02: Basic Formulae for Nucleosynthesis Calculations

2003 ◽  
Vol 20 (4) ◽  
pp. 389-392 ◽  
Author(s):  
O. Straniero ◽  
I. Domínguez ◽  
S. Cristallo ◽  
R. Gallino
Keyword(s):  
Effective Temperature ◽  
Convective Instability ◽  
Convective Zone ◽  
Maximum Temperature ◽  
Core Mass ◽  
Convective Envelope ◽  
Appropriate Treatment ◽  
Low Mass ◽  
Thermal Pulses ◽  
Radiative Opacity

AbstractWe have extended our published set of low-mass AGB stellar modelsto lower metallicities. Different mass-loss rates have been explored. We provide interpolation formulae for the luminosity, effective temperature, core mass, mass of dredge up material and maximum temperature in the convective zone generated by thermal pulses. Finally, we discuss the resultant modification of these quantities when we use an appropriate treatment of the inward propagation of the convective instability, as caused by the steeprise in radiative opacity when the convective envelope penetratesthe H-depleted region.

scholarly journals Core-hydrogen-burning RSGs in the early globular clusters

2015 ◽  
Vol 11 (A29B) ◽  
pp. 473-473
Author(s):  
Dorottya Szécsi ◽  
Jonathan Mackey ◽  
Norbert Langer
Keyword(s):  
Globular Clusters ◽  
Stellar Population ◽  
Massive Stars ◽  
Shell Formation ◽  
Low Mass Stars ◽  
Hydrogen Burning ◽  
The Core ◽  
Anomalous Surface ◽  
Low Metallicity ◽  
Low Mass

AbstractThe first stellar generation in galactic globular clusters contained massive low-metallicity stars (Charbonnel et al. 2014). We modelled the evolution of this massive stellar population and found that such stars with masses 100-600 M⊙ evolve into cool RSGs (Szécsi et al. 2015). These RSGs spend not only the core-He-burning phase but even the last few 105 years of the core-H-burning phase on the SG branch. Due to the presence of hot massive stars in the cluster at the same time, we show that the RSG wind is trapped into photoionization confined shells (Mackey et al. 2014). We simulated the shell formation around such RSGs and find them to become gravitationally unstable (Szécsi et al. 2016). We propose a scenario in which these shells are responsible for the formation of the second generation low-mass stars in globular clusters with anomalous surface abundances.

scholarly journals Asymptotic Giant Branch Stars: Thermal Pulses, Carbon Production, and Dredge Up; Neutron Sources and s-Process Nucleosynthesis

1991 ◽  
Vol 145 ◽  
pp. 257-274
Author(s):  
Icko Iben
Keyword(s):  
Neutron Source ◽  
Lower Boundary ◽  
Source Model ◽  
Asymptotic Giant Branch ◽  
Asymptotic Giant Branch Stars ◽  
Agb Stars ◽  
Core Mass ◽  
Convective Envelope ◽  
Thermal Pulses ◽  
Giant Branch Stars

A brief review is given of the structure of asymptotic giant branch (AGB) stars and of the characteristics of the thermal pulses which these stars experience. Following a pulse, model AGB stars with a large core mass easily dredge up fresh carbon, which is the main product of incomplete helium burning, and s-process isotopes, which are made as a consequence of the activation of the 22Ne neutron source. Model AGB stars of small core mass activate the 13C neutron source and produce s-process isotopes in nearly the solar system distribution. They also dredge up fresh carbon and s-process isotopes, but only if overshoot or some other form of “extra” mixing beyond the lower boundary of the convective envelope is invoked.

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