The Ideal Gas with Radiation

Kippenhahn, Rudolf; Weigert, Alfred

doi:10.1007/978-3-642-61523-8_13

Cited by 11 publications

(15 citation statements)

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“…T h e luminosity of a giant star at the Hayashi limit depends practically only on the mass of its core (Paczyriski, 1970;Kippenhahn, 1981). This statement holds, in general, also for stars on the A G B since it is mainly hydrogen burning t h a t determines the overall course of evolution, i.e.…”

Section: A S S Loss and Evolution Along The A G Bmentioning

confidence: 99%

Evolutionary Tracks

Schönberner

1993

Symp. - Int. Astron. Union

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It is now accepted without any doubts that the central stars of Planetary Nebulae (CPN) are rapidly evolving objects in the transition from the asymptotic giant branch (AGB) to the white-dwarf regime. After the pioneering study of Paczyński (1971) it has been demonstrated by Schönberner (1981) that Paczyński's calculations are too crude for the understanding of post-AGB evolution because the latter depends very sensitively on the detailed internal stellar structure, i.e. on the past AGB evolution. More precisely, the evolution of an AGB remnant is a function of the thermal-pulse cycle phase ϕ during which this remnant has been created by the planetary-nebula (PN) formation process. This has been shown by Schönberner (1979, 1983) and later fully been explored by Iben (1984).

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Section: A S S Loss and Evolution Along The A G Bmentioning

confidence: 99%

Evolutionary Tracks

Schönberner

1993

Symp. - Int. Astron. Union

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“…For a fixed chemical composition, turbulence in the convective envelope and mass, the electron degeneracy is lifted at a fixed core mass via rapid triple´α nuclear burning into carbon and oxygen. Because there is a very well-defined relationship between core mass and luminosity ( [1,2]), this results in a very well-defined luminosity of the tip of the red giant branch (TRGB) very evident in a Color-Magnitude diagram. Once the degeneracy is lifted, the stellar luminosity decreases dramatically as helium burning starts in the core and the star settles on the horizontal branch [1].…”

Section: Introductionmentioning

confidence: 99%

“…Because there is a very well-defined relationship between core mass and luminosity ( [1,2]), this results in a very well-defined luminosity of the tip of the red giant branch (TRGB) very evident in a Color-Magnitude diagram. Once the degeneracy is lifted, the stellar luminosity decreases dramatically as helium burning starts in the core and the star settles on the horizontal branch [1]. This fact has been exploited as a calibration to measure astronomical distances; recently, this technique has been used to obtain 2 ´3% precision in the determination of the Hubble constant [3].…”

Section: Introductionmentioning

confidence: 99%

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Giants eating giants: Mass loss and giant planets modifying the luminosity of the Tip of the Giant Branch

Jimenez,

Jorgensen,

Verde

2020

Preprint

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During the red giant phase, stars loose mass at the highest rate since birth. The mass-loss rate is not fixed, but varies from star-to-star by up to 5%, resulting in variations of the star's luminosity at the tip of the red giant branch (TRGB). Also, most stars, during this phase, engulf part of their planetary system, including their gas giant planets. Gas giant planet masses range between 0.1 to 2% of the host star mass. The engulfing of their gas giants planets can modify their luminosity at the TRGB, i.e. the point at which the He-core degeneracy is removed. We show that the increase in mass of the star by the engulfing of the gas giant planets only modifies the luminosity of a star at the TRGB by less than 0.1%, while metallicity can modify the luminosity of a star at the TRGB by up to 0.5%. However, the increase in turbulence of the convective envelope of the star, i.e., modification of the mixing length, has a more dramatic effect, on the star's luminosity, which we estimate could be as large as 5%. The effect is always in the direction to increase the turbulence and thus the mixing length which turns into a systematic decrease of the luminosity of the star at the TRGB. We find that the star-to-star variation of the mass-loss rate will dominate the variations in the luminosity of the TRGB with a contribution at the 5% level. If the starto-star variation is driven by environmental effects -as it is reasonable to assume-, the same effects can potentially create an environmentally-driven mean effect on the luminosity of the tip of the red giant branch of a galaxy. Finally, we touch upon how to infer the frequency, and identify the engulfment, of exoplanets in low-metallicity RGB stars through high resolution spectroscopy as well as how to quantify mass loss rate distributions from the morphology of the horizontal branch.

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“…Based on far-infrared data taken by the Infrared Astronomy Satellite, Puche et al (1988) find a total far-infrared luminosity of L * = D 6 kpc 10 5 L , where D is the nebula's distance in kiloparsecs. If the range in planetary nebula nucleus masses is taken to be 0.5 M to 0.8 M (Pauldrach et al 1988), then the theoretical upper limit to the luminosity of PNe is ≈ 20000 L based on models of Paczynski (1970) and Kippenhahn (1981). Ultracompact HII region regions are young objects, and as such they are assumed to have much smaller peculiar velocities than do PNe; that is, their motion is expected to follow the Galactic rotation curve more closely.…”

Section: ) Introductionmentioning

confidence: 99%

The Classification of M 1-78

Gussie¹

1995

Publ. Astron. Soc. Aust.

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The published properties of M 1-78 are discussed with the purpose to resolve the object's classification as either a planetary nebula or an ultracompact HII region. A classification as a planetary nebula is rejected primarily because of the high luminosity of the object, but because of the chemical composition and expansion velocity of the nebula, a novel classification is proposed instead: that of an ultracompact HII region with a post-main sequence central star (possibly a WN star). It must therefore follow that observable ultracompact HII regions persist beyond the main sequence lifetimes of at least some massive stars, and so cannot be transient phenomena that are seen only during pre-main sequence or early main sequence evolution.

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The Ideal Gas with Radiation

Cited by 11 publications

References 0 publications

Evolutionary Tracks

Evolutionary Tracks

Giants eating giants: Mass loss and giant planets modifying the luminosity of the Tip of the Giant Branch

The Classification of M 1-78

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