Improved angular momentum evolution model for solar-like stars II. Exploring the mass dependence

By F. Gallet, J. Bouvier. 2015

178 citations recorded by the source corpus.

We developed angular momentum evolution models for 0.5 and 0.8 $M_{\odot}$ stars. The parametric models include a new wind braking law based on recent numerical simulations of magnetised stellar winds, specific dynamo and mass-loss rate prescriptions, as well as core/envelope decoupling. We compare model predictions to the distributions of rotational periods measured for low mass stars belonging to star forming regions and young open clusters. Furthermore, we explore the mass dependence of model parameters by comparing these new models to the solar-mass models we developed earlier. Rotational evolution models are computed for slow, median, and fast rotators at each stellar mass. The models reproduce reasonably well the rotational behaviour of low-mass stars between 1 Myr and 8-10 Gyr, including pre-main sequence to zero-age main sequence spin up, prompt zero-age main sequence spin down, and early-main sequence convergence of the surface rotation rates. Fast rotators are found to have systematically shorter disk lifetimes than moderate and slow rotators, thus enabling dramatic pre-main sequence spin up. They also have shorter core-envelope coupling timescales, i.e., more uniform internal rotation. As to the mass dependence, lower mass stars require significantly longer core-envelope coupling timescale than solar-type ones, which results in strong differential rotation developing in the stellar interior on the early main sequence. Lower mass stars also require a weaker braking torque to account for their longer spin down timescale on the early main sequence, while they ultimately converge towards lower rotational velocities than solar-type stars on the longer term due to their reduced moment of inertia. We also find evidence that the mass-dependence of the wind braking efficiency may be related to a change of the magnetic topology in lower mass stars.

Subfields: Astronomy and Astrophysics, Instrumentation, Statistical and Nonlinear Physics

View Paper: https://www.semanticscholar.org/paper/3cb16d7bf9ef6f3ac9e97ef4794e0230f081cccd

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In Astronomy and Astrophysics

1. J. Fuller
2. M. Gudel
3. H. Lammer
4. A. Piro
5. J. Owen
6. Colin P. Johnstone
7. I. Brott
8. T. Lüftinger

In Instrumentation

1. M. Gudel
2. H. Lammer
3. I. Brott
4. T. Lüftinger
5. Colin P. Johnstone
6. Lin Tu
7. J. Fuller
8. A. Piro

In Statistical and Nonlinear Physics

1. Colin P. Johnstone
2. Lin Tu
3. J. Fuller
4. M. Gudel
5. H. Lammer
6. A. Piro
7. Adam S. Jermyn

Citations in the corpus

• The Extreme Ultraviolet and X-Ray Sun in Time: High-Energy Evolutionary Tracks of a Solar-Like Star (2015, methodology): “We use the core-envelope decoupling model described by Gallet & Bouvier (2015) and adopt coupling timescales of 30 Myr, 20 Myr, and 10 Myr for the 10th, 50th and 90th percentile tracks, respectively, which we findgive us good agreement between the rotational evolution model and the observations.”
• Slowing the spins of stellar cores (2019, background): “…3661–3680 (2019) D ow nloaded from https://academ ic.oup.com /m nras/article-abstract/485/3/3661/5347954 by C alifornia Institute of Technology user on 25 April 2019 2010; Gallet & Bouvier 2015; Lanzafame & Spada 2015) find evidence for core-envelope coupling times in the range tAM ∼ 10–100 Myr.”
• Stellar winds on the main-sequence - II. The evolution of rotation and winds (2015, background): “Gallet & Bouvier (2015) suggested that the mass loss rates of the 0.5 M stars should be increased by a factor of 860 relative to what they would otherwise predict, which would be much more consistent with our results.”