Slowing the spins of stellar cores

Fuller, Jim; Piro, Anthony L.; Jermyn, Adam S.

doi:10.1093/mnras/stz514

Cited by 291 publications

(379 citation statements)

References 74 publications

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“…We note that the differences in AM transport efficiency between the prescriptions proposed by Fuller et al (2019) and Spruit (2002) are already visible on the MS; there is a significant impact on the core rotation rate predicted for the Sun (Eggenberger et al 2019a). Owing to its capability of efficiently transporting AM, the expression for the transport by the Tayler instability proposed by Fuller et al (2019) constitutes a promising candidate for the missing poMS transport process. The key question is to determine whether this mechanism is able to reproduce the asteroseismic constraints mentioned above.…”

Section: Introductionmentioning

confidence: 76%

“…Models of subgiant and red giant stars are computed with the Geneva stellar evolution code (Eggenberger et al 2008) using the assumption of shellular rotation (Zahn 1992). The internal AM transport is then followed simultaneously to the evolution of the star by taking into account meridional circulation, shear instability, and AM transport by the magnetic Tayler instability as proposed by Fuller et al (2019). The following equation is then solved for AM transport in radiative zones:…”

Section: Input Physics Of the Modelsmentioning

confidence: 99%

“…The minimum value of radial differential rotation needed for the magnetic AM transport to operate is given by (Eq. 36 of Fuller et al 2019)…”

Section: Input Physics Of the Modelsmentioning

confidence: 99%

“…We investigated the robustness of these results compared to the use of a different evolution code (that can differ in the input physics and the numerical methods used) using the MESA code (Paxton et al 2011(Paxton et al , 2013(Paxton et al , 2015(Paxton et al , 2018(Paxton et al , 2019. Models were then computed with the MESA code (revision 11701) with the same implementation of AM transport as described in Fuller et al (2019). Models of the red giant KIC 4448777 computed with both codes with similar input parameters are shown in Fig.…”

Section: Rotational Properties Of Subgiant Starsmentioning

confidence: 99%

“…The key question is to determine whether this mechanism is able to reproduce the asteroseismic constraints mentioned above. In particular, we seek to find out whether the magnetic transport process recently proposed by Fuller et al (2019) is compatible with the internal rotation of subgiant stars as deduced from asteroseismic measurements.…”

Section: Introductionmentioning

confidence: 99%

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Asteroseismology of evolved stars to constrain the internal transport of angular momentum

Eggenberger

Deheuvels

Miglio

et al. 2019

A&A

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Context. Asteroseismic observations enable the characterisation of the internal rotation of evolved stars. These measurements reveal that an unknown efficient angular momentum (AM) transport mechanism is needed for subgiant and red giant stars in addition to hydrodynamic transport processes. A revised prescription for AM transport by the magnetic Tayler instability has been recently proposed as a possible candidate for such a missing mechanism. Aims. We compare the rotational properties predicted by this magnetic AM transport to asteroseismic constraints obtained for evolved stars with a particular focus on the subgiant phase. Methods. We computed models accounting for the recent prescription for AM transport by the Tayler instability with the Geneva stellar evolution code for subgiant and red giant stars, for which an asteroseismic determination of both core and surface rotation rates is available. Results. The revised prescription for the transport by the Tayler instability leads to low core rotation rates after the main sequence that are in better global agreement with asteroseismic measurements than those predicted by models with purely hydrodynamic processes or with the original Tayler-Spruit dynamo. A detailed comparison with asteroseismic data shows that the rotational properties of at most two of the six subgiants can be correctly reproduced by models accounting for this revised magnetic transport process. This result is obtained independently of the value adopted for the calibration parameter in this prescription. We also find that this transport by the Tayler instability faces difficulties in simultaneously reproducing asteroseismic measurements available for subgiant and red giant stars. The low values of the calibration parameter needed to correctly reproduce the rotational properties of two of the six subgiants lead to core rotation rates during the red giant phase that are too high. Inversely, the higher values of this parameter needed to reproduce the core rotation rates of red giants lead to a very low degree of radial differential rotation before the red giant phase, which is in contradiction with the internal rotation of subgiant stars. Conclusions. In its present form, the revised prescription for the transport by the Tayler instability does not provide a complete solution to the missing AM transport revealed by asteroseismology of evolved stars.

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