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Red horizontal branch stars: An asteroseismic perspective
Astronomy and Astrophysics, 2023 Robust age estimates of red giant stars are now possible thanks to the precise inference of their mass based on asteroseismic constraints. However, there are cases where such age estimates can be highly precise yet very inaccurate. An example is giants that have undergone mass loss or mass transfer events that have significantly altered their mass.
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Astrophysics and Space Science, 1969
Evolutionary tracks of 0.9M ⊙, 0.7M ⊙ and 0.6M ⊙ models for Population II stars have been computed in the post-red giant phase. The stars are initially composed of a helium core containing a mass fraction equal to 0.9 and of a hydrogen-rich envelope.
V. Castellani, P. Giannone, A. Renzini
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Evolutionary tracks of 0.9M ⊙, 0.7M ⊙ and 0.6M ⊙ models for Population II stars have been computed in the post-red giant phase. The stars are initially composed of a helium core containing a mass fraction equal to 0.9 and of a hydrogen-rich envelope.
V. Castellani, P. Giannone, A. Renzini
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Current problems on horizontal branch stars
Astrophysics and Space Science, 1973In the light of present knowledge on stellar evolution, it is shown that red ZAHB will not develop for very low metal globular clusters if Y is appreciably greater than 0.1. Recent determinations of the mass-sizes of the Re- cores at the time of the He-flash support independently conclusion that, if no increase in surface He-abundanice occurs between ...
F. Caputo, A. Natta, V. Castellani
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On the identification of field horizontal-branch A stars
Publications of the Astronomical Society of the Pacific, 1991Field horizontal-branch A-star candidates are found by spectroscopic and colorimetric surveys. To confirm their status four-color, H-beta photometry and ultraviolet spectrophotometry have been employed. In this paper, the importance of high-dispersion spectroscopy to identify nonclass members by inspection is demonstrated.
A. G. Davis Philip, Saul J. Adelman
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A-Type Horizontal-Branch Stars
1975Horizontal-branch stars have attracted our attention as conspicuous examples of highly evolved population-II stars. Recent developments in the theoretical calculations of the internal structure of horizontal-branch stars (see Rood, 1970; Demarque and Mengel, 1971; Sweigart and Demarque, 1972) enable detailed studies on the evolutionary tracks ...
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Current problems on horizontal branch stars
Astrophysics and Space Science, 1975Expected characteristics of RR Lyrae stars as a function of the evolutive parameters are reported. Results from both evolutionary and pulsational investigations are collected in a suitable form, to show the general constraints to any interpretative analysis of the observations.
Filippina Caputo, Vittorio Castellani
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Convective Overshooting in Horizontal Branch Stars
1987The evolution of horizontal branch stars up to the starting of the thermally pulsing regime of the He-burning shell is investigated with the aid of a non local treatment of the core convection. The formalism follows the overshooting model by Bressan et al (1981) which opposes to the classical, local schemes for overshooting and semiconvection currently
C. Chiosi, G. Bertelli, A. Bressan
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Anomalies in horizontal branch stars of globular clusters and SdB stars
EAS Publications Series, 2005I review the chemical abundance measurements of blue horizontal branch stars within the theoretical framework of diffusion and radiative levitation. The present observational scenario reports normal abundances for stars cooler than T eff ~ 11 000 K, while largely anomalous abundances for hotter stars are found. In particular, large He depletions and
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