Volume 634, February 2020
|Number of page(s)||4|
|Section||Letters to the Editor|
|Published online||24 February 2020|
Letter to the Editor
Asteroseismology of evolved stars to constrain the internal transport of angular momentum
III. Using the rotation rates of intermediate-mass stars to test the Fuller-formalism
Konkoly Observatory, CSFK, Konkoly Thege Miklós út 15-17, 1121 Budapest, Hungary
2 Astrophysics Group, Lennard-Jones Laboratories, Keele University, ST5 5BG Newcastle, UK
3 Observatoire de Genève, Université de Genève, 51 Ch. des Maillettes, 1290 Sauverny, Switzerland
4 IRAP, Université de Toulouse, CNRS, CNES, UPS, Toulouse, France
Accepted: 7 February 2020
Context. The internal characteristics of stars, such as their core rotation rates, are obtained via asteroseismic observations. A comparison of core rotation rates found in this way with core rotation rates as predicted by stellar evolution models demonstrate a large discrepancy. This means that there must be a process of angular momentum transport missing in the current theory of stellar evolution. A new formalism was recently proposed to fill in for this missing process, which has the Tayler instability as its starting point (by Fuller et al. 2019, MNRAS, 485, 3661, hereafter referred to as “Fuller-formalism”).
Aims. We investigate the effect of the Fuller-formalism on the internal rotation of stellar models with an initial mass of 2.5 M⊙.
Methods. Stellar evolution models, including the Fuller-formalism, of intermediate-mass stars were calculated to make a comparison between asteroseismically obtained core rotation rates in the core He burning phase and in the white dwarf phase.
Results. Our main results show that models including the Fuller-formalism can match the core rotation rates obtained for the core He burning phases. However, these models are unable to match the rotation rates obtained for white dwarfs. When we exclude the Fuller-formalism at the end of the core He burning phase, the white dwarf rotation rates of the models match the observed rates.
Conclusions. We conclude that in the present form, the Fuller-formalism cannot be the sole solution for the missing process of angular momentum transport in intermediate-mass stars.
Key words: stars: evolution / stars: rotation / stars: interiors / stars: oscillations
NuGrid Collaboration, http://www.NuGridstars.org
© ESO 2020
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