Mira variables, mass loss, and the fate of red giant stars

Wood, P. R.; Cahn, J. H.

doi:10.1086/154957

Cited by 112 publications

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“…The present sample is naturally biased towards stars with low circumstellar extinction because the Tc lines are located in the blue spectral range, so that stars in the late superwind phase of the AGB are missing. Also, most sample stars have periods shorter than 500 d. It is known that the number density of optically visible Mira variables drops sharply between P = 425 and 500 d (Wood & Cahn 1977).…”

Section: The Datamentioning

confidence: 99%

Period – mass-loss rate relation of Miras with and without technetium

Uttenthaler

2013

A&A

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Aims. We report the discovery that Mira variables with and without absorption lines of the element technetium (Tc) occupy two different regions in a diagram of near-to mid-IR colour versus pulsation period. Tc is an indicator of a recent or ongoing mixing event called the third dredge-up (3DUP), and the near-to mid-IR colour, such as the (K − [22]) colour where [22] is the the 22 μm band of the WISE space observatory, is an indicator of the dust mass-loss rate of a star. Methods. We collected data from the literature about the Tc content, pulsation period, and near-and mid-IR magnitudes of more than 190 variable stars on the asymptotic giant branch (AGB) to which Miras belong. The sample is naturally biased towards optical AGB stars, which have low to intermediate (dust) mass-loss rates. Results. We show that a clear relation between dust mass-loss rate and pulsation period exists if a distinction is made between Tc-poor and Tc-rich Miras. Surprisingly, at a given period, Tc-poor Miras are redder in (K − [22]) than are Tc-rich Miras; i.e., they have higher mass-loss rates than the Tc-rich Miras. A few stars deviate from this trend; physical explanations are given for these exceptions, such as binarity or high mass. Conclusions. We put forward two hypotheses to explain this dichotomy and conclude that the two sequences formed by Tc-poor and Tc-rich Miras are probably due to the different masses of the two groups. The pulsation period has a strong correlation with the dust-mass loss rate, indicating that the pulsations are indeed triggering a dust-driven wind. The location in the (K − [22]) vs. period diagram can be used to distinguish between pre-and post-3DUP Miras, which we apply to a sample of Galactic bulge AGB stars. We find that 3DUP is probably not common in AGB stars in the inner bulge.

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Section: The Datamentioning

confidence: 99%

Period – mass-loss rate relation of Miras with and without technetium

Uttenthaler

2013

A&A

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“…When this happens the envelope is rapidly ejected Tsuperwind regime) and the AGB phase is terminated (Wood and Cahn 1977;Iben and Truran 1978;Renzini and Voli 1981;Ren zini 198la,b;Iben and Renzini 1982). During the superwind regime M e is rapidly decreasing, and when another critical value of the envelope mass is reached (M J the star begins to depart from the AGB, moving to available at https://www.cambridge.org/core/terms.…”

Section: Low Mass Wolf-rayet Starsmentioning

confidence: 99%

Low Mass Wolf-Rayet Stars: Theory

Renzini

1982

Symp. - Int. Astron. Union

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It is well known that the Wolf-Rayet phenomenon is not restricted to some bright and massive stars, presumably in their core hydrogen-burning or helium-burning phase, but that it is also encountered among the central stars of some planetary nebulae (PNe). The PN nuclei are generally regarded as the evolutionary product of low and intermediate mass stars (with initial masses M.1 below ∼5 M⊙), which have lost most of their hydrogen-rich envelope during the so-called Asymptotic Giant Branch (AGB) phase. Correspondingly, their present mass cannot exceed the Chandrasekhar limit (∼1.4 M⊙), and their internal structure consists of a highly degenerate carbon-oxygen core containing most of the stellar mass, surrounded by an intershell region of mass ΔMCSH, and by a very low-mass envelope (Me < ∼10−3 M⊙).

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“…with progenitor masses above « l^.gup to M w t>, must go through the PN stage, and until there is evidence against it, we shall use this as a working hypothesis. I should mention in this context that the evolutionary scheme proposed and discussed by Wood and Cahn (1977) and Cahn and Wyatt (1978) which evaluates information about the Mira period-distribution -with Miras again considered as immediate progenitors of PN stages -leads to the conclusion that stars below 1.25>l 0 do not go through a PN stage but evolve directly into white dwarfs by steady mass loss. Similarly, calculations of evolution with steady mass loss according to the Reimers formula, through the double-shell burning stage into the white dwarf region -by Schonberner (1979) in Kiel -indicate that stars below 1.4>f e may lose their envelopes by stellar winds only.…”

Section: Planetary Nebulaementioning

confidence: 99%

“…This qualitative picture, so far, has been known and accepted for some time, and was first incorporated into a quantitative study of galactic evolution by Ostriker and coworkers (Thuan et al, 1975). During the last years, however, it has become evident that mass loss plays a much more important role than anticipated, both steady and unsteady, in stellar winds and/or planetary nebulae (see Reimers,1975, Weidemann 1977a, Wood and Cahn, 1977, Renzini, 1979. Recent investigations about white dwarf members in open clusters (Romanishin and Angel, 1979) have shown that progenitor masses for white dwarf production may be as high as 1H 9 with a stringent lower limit of 5 M 9 .…”

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confidence: 91%

Origin and Distributions of White Dwarfs

Weidemann¹

1979

International Astronomical Union Colloquium

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Today there is no doubt that white dwarfs represent the most common final stage of stellar evolution. Considerable progress has been made during the last decade in our understanding of their origin and distributions. This is reflected by the fact that it is now possible to predict -from basic theory of stellar evolution and stellar atmospheres -the existence of cooling degenerate stars with nearly the observed properties, i.e. a sequence of white dwarfs which fill in their majority a narrow strip in both two-color and colormagnitude diagrams. With other words: the empirically determined surface gravity and radius distributions -which correspond via the mass-radius relation to mass distributions -can now be basically understood within the currently adopted general scheme of stellar evolution with mass loss.For the first time this opens the possibility of a synthetic approach which I shall adopt in the following. Crude as it may be it nevertheless sets the stage on which we then may post our more detailed questions and judge in which way we may try to answer them.We therefore assume that stars are born on the main sequence in numbers determined by a time-independent initial mass function (IMF) in a global rate which depends in a defined way on the time in the past, within a specified age of the Galaxy. We let these stars evolve according to currently accepted theory for single stars, through central hydrogen-, shell-, central helium-and double-shell-burning phases until the nuclear evolution is terminated either by fuel exhaustion in a growing degenerate C/O-core with envelope mass loss or by gravitational collapse and supernova explosion. If we assume the course of this evolution to depend on the initial mass only we arrive at a defined relation between initial and final masses, J~\^.(Mi). The main sequence birth rate then determines -delayed by the total time of nuclear evolution, and projected by the Mf. -%M; relation -the white dwarf (and supernova) birth rate at any chosen epoque of galactic evolution, as well as their mass distribution. This qualitative picture, so far, has been known and accepted for some time, and was first incorporated into a quantitative study of galactic evolution by Ostriker and coworkers (Thuan et al., 1975). During the last years, however, it has become evident that mass loss plays a much more important role than anticipated, both steady and unsteady, in stellar winds and/or planetary nebulae (see Reimers,1975, -206-https://www.cambridge.org/core/terms. https://doi

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Mira variables, mass loss, and the fate of red giant stars

Cited by 112 publications

References 0 publications

Period – mass-loss rate relation of Miras with and without technetium

Period – mass-loss rate relation of Miras with and without technetium

Low Mass Wolf-Rayet Stars: Theory

Origin and Distributions of White Dwarfs

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