Thermal pulses; p-capture, alpha-capture, s-process nucleosynthesis; and convective mixing in a star of intermediate mass

Several physical processes taking place during the red (super)giant phase of intermediate-mass stars have direct observational consequences for the subsequent nebular stage. These processes include: the regular wind and the envelope ejection, the thermal pulses during the AGB phase, the dredge-up processes, and the dust formation in expanding circumstellar envelopes. In this paper it is briefly discussed how such processes affect the mass range of PN nuclei and their evolution, and the PN lifetime, composition and dust content. The last section is devoted to a cursory discussion of PNe which can be generated by binary stars.

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More Details on Thermal Pulses and the Third Dredge-Up Process in Intermediate-Mass Stars

Astrophysics and Space Science Library - Physical Processes in Red Giants ◽

10.1007/978-94-009-8492-9_12 ◽

1981 ◽

pp. 141-146 ◽

Cited By ~ 12

Author(s):

Stephen Allan Becker

Keyword(s):

Intermediate Mass ◽

The Third ◽

Intermediate Mass Stars ◽

Thermal Pulses

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Hiding in plain sight - red supergiant imposters? Super-AGB stars

Proceedings of the International Astronomical Union ◽

10.1017/s1743921316005767 ◽

2015 ◽

Vol 11 (A29B) ◽

pp. 446-446

Author(s):

Carolyn Doherty ◽

Pilar Gil-Pons ◽

John Lattanzio ◽

Lionel Siess

Keyword(s):

Neutron Star ◽

White Dwarf ◽

Mass Range ◽

Asymptotic Giant Branch ◽

Agb Stars ◽

Intermediate Mass ◽

Stellar Envelope ◽

The Core ◽

Stellar Envelopes ◽

Thermal Pulses

AbstractSuper Asymptotic Giant Branch (Super-AGB) stars reside in the mass range ≈ 6.5-10 M⊙ and bridge the divide between low/intermediate-mass and massive stars. They are characterised by off-centre carbon ignition prior to a thermally pulsing phase which can consist of many tens to even thousands of thermal pulses. With their high luminosities and very large, cool, red stellar envelopes, these stars appear seemingly identical to their slightly more massive red supergiant counterparts. Due to their similarities, super-AGB stars may therefore act as stellar imposters and contaminate red supergiant surveys. The final fate of super-AGB stars is also quite uncertain and depends primarily on the competition between the core growth and mass-loss rates. If the stellar envelope is removed prior to the core reaching ≈ 1.375 M⊙, an O-Ne white dwarf will remain, otherwise the star will undergo an electron-capture supernova (EC-SN) leaving behind a neutron star. We determine the relative fraction of super-AGB stars that end life as either an O-Ne white dwarf or as a neutron star, and provide a mass limit for the lowest mass supernova over a broad range of metallicities from the Z=0.02 to 0.0001.

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Thermal Pulses and the Formation of Planetary Nebula Shells

Symposium - International Astronomical Union ◽

10.1017/s0074180900138793 ◽

1989 ◽

Vol 131 ◽

pp. 391-400 ◽

Cited By ~ 6

Author(s):

Alvio Renzini

Keyword(s):

Stellar Evolution ◽

Planetary Nebula ◽

White Dwarfs ◽

Asymptotic Giant Branch ◽

Formation Processes ◽

Intermediate Mass ◽

The Past ◽

Intermediate Mass Stars ◽

Thermal Pulses

Over the past decade a comprehensive, semiquantitative theoretical scenario for the final evolutionary stages of low and intermediate mass stars has been progressively elaborated and refined. It concerns the envelope ejection terminating the Asymptotic Giant Branch (AGB) phase, the AGB to Planetary Nebula (PN) transition, the fading and possible rejuvenation of PN nuclei, the formation processes of hydrogen-deficient stars, and the final production of white dwarfs (WD) of the DA and non-DA varieties (Renzini 1979, 1981a, 1981b, 1982, 1983, Iben & Renzini 1983, Iben et al. 1983, Iben 1984, 1985, 1987, Iben & Tutukov 1984, Iben & MacDonald 1985, 1986). In developing this scenario several important results of stellar evolution and hydrodynamical calculations have been incorporated, including in particular those of Paczynski (1971), Wood (1974), Härm & Schwarzschild (1975), Schönberner (1979, 1983), and Tuchman, Sack & Barkat (1979).

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Are s-elements really produced during thermal pulses in intermediate-mass stars?

The Astrophysical Journal ◽

10.1086/166081 ◽

1988 ◽

Vol 326 ◽

pp. 196 ◽

Cited By ~ 33

Author(s):

M. Busso ◽

G. Picchio ◽

R. Gallino ◽

A. Chieffi

Keyword(s):

Intermediate Mass ◽

Intermediate Mass Stars ◽

Thermal Pulses

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Nucleosynthesis in Intermediate-Mass Stars

Symposium - International Astronomical Union ◽

10.1017/s0074180900002722 ◽

2000 ◽

Vol 177 ◽

pp. 449-458 ◽

Cited By ~ 3

Author(s):

John C. Lattanzio ◽

Cheryl A. Frost ◽

Robert C. Cannon ◽

Peter R. Wood

Keyword(s):

Intermediate Mass ◽

Intermediate Mass Stars ◽

Thermal Pulses

We discuss nucleosynthesis within 6 M⊙ models with Z = 0.02, 0.008 and 0.004. The emphasis is on the AGB phase of evolution, with particular reference to thermal pulses and Hot Bottom Burning. We find strong CN cycling, with substantial Al production, especially at low metallicities.

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Nucleosynthesis in AGB Stars

Symposium - International Astronomical Union ◽

10.1017/s0074180900202854 ◽

1999 ◽

Vol 191 ◽

pp. 31-40 ◽

Cited By ~ 12

Author(s):

John Lattanzio ◽

Manuel Forestini

Keyword(s):

Agb Stars ◽

Carbon Stars ◽

Intermediate Mass ◽

Qualitative Review ◽

Intermediate Mass Stars ◽

Thermal Pulses

We give a qualitative review of the nucleosynthesis occurring in AGB stars. We summarise some new calculations of intermediate mass stars which include all thermal pulses until the star is about to leave the AGB, as well as a detailed nucleosynthesis network. We will show that hot bottom burning delays, rather than prevents, the formation of carbon stars; those that form are not optically visible.

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Convective mixing in intermediate mass stars

Proceedings of the International Astronomical Union ◽

10.1017/s1743921316004683 ◽

2015 ◽

Vol 11 (A29B) ◽

pp. 156-157

Author(s):

Alessandro Bressan

Keyword(s):

Predictive Power ◽

Stellar Population ◽

Population Synthesis ◽

Intermediate Mass ◽

Convective Mixing ◽

Intermediate Mass Stars ◽

Stellar Population Synthesis ◽

Nuclear Burning ◽

Advanced Stages ◽

High Degree

AbstractStellar evolution can nowadays be modelled with a high degree of accuracy and completeness up to the most advanced stages. However in spite of the progresses, complex physical processes exist that still suffer of large uncertainties even in the most placid evolutionary phases. The straightforward drawback is that models lose their predictive power and this is particularly critical for stellar population synthesis. Here I will focus on one of such processes, convective mixing, and briefly review potentially helpful observational tests to decipher its efficiency during the main nuclear burning phases of intermediate mass stars.

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