Rotating models of young solar-type stars

Exploring braking laws and angular momentum transport processes

¹ LUPM, Université de Montpellier, CNRS, Place E. Bataillon – cc 072, 34095 Montpellier Cedex 05, France
e-mail: louis.amard@umontpellier.fr
² Department of Astronomy, University of Geneva, Chemin des Maillettes 51, 1290 Versoix, Switzerland
³ IRAP, UMR 5277, CNRS and Université de Toulouse, 14 Av. E. Belin, 31400 Toulouse, France
⁴ Université Grenoble Alpes, IPAG, 38000 Grenoble, France
⁵ CNRS, IPAG, 38000 Grenoble, France

Received: 11 September 2015
Accepted: 22 December 2015

Abstract

Context. Understanding the angular momentum evolution of stars is one of the greatest challenges of modern stellar physics.

Aims. We study the predicted rotational evolution of solar-type stars from the pre-main sequence to the solar age with 1D rotating evolutionary models including physical ingredients.

Methods. We computed rotating evolution models of solar-type stars including an external stellar wind torque and internal transport of angular momentum following the method of Maeder and Zahn with the code STAREVOL. We explored different formalisms and prescriptions available from the literature. We tested the predictions of the models against recent rotational period data from extensive photometric surveys, lithium abundances of solar-mass stars in young clusters, and the helioseismic rotation profile of the Sun.

Results. We find a best-matching combination of prescriptions for both internal transport and surface extraction of angular momentum. This combination provides a very good fit to the observed evolution of rotational periods for solar-type stars from early evolution to the age of the Sun. Additionally, we show that fast rotators experience a stronger coupling between their radiative region and the convective envelope. Regardless of the set of prescriptions, however, we cannot simultaneously reproduce surface angular velocity and the internal profile of the Sun or the evolution of lithium abundance.

Conclusions. We confirm the idea that additional transport mechanisms must occur in solar-type stars until they reach the age of the Sun. Whether these processes are the same as those needed to explain recent asteroseismic data in more advanced evolutionary phases is still an open question.