Improved angular momentum evolution model for solar-like stars

By F. Gallet, J. Bouvier. 2013

280 citations recorded by the source corpus.

Context. Understanding the origin and evolution of stellar angular momentum is one of the major challenges of stellar physics. Aims. We present new models for the rotational evolution of solar-like stars between 1 Myr and 10 Gyr with the aim of reproducing the distributions of rotational periods observed for star forming regions and young open clusters within this age range. Methods. The models include a new wind braking law based on recent numerical simulations of magnetized stellar winds and specific dynamo and mass-loss prescriptions are adopted to tie angular momentum loss to angular velocity. The models additionally assume constant angular velocity during the disk accretion phase and allow for decoupling between the radiative core and the convective envelope as soon as the former develops. Results. We have developed rotational evolution models for slow, median, and fast rotators with initial periods of 10, 7, and 1.4 d, respectively. The models reproduce reasonably well the rotational behavior of solar-type stars between 1 Myr and 4.5 Gyr, including pre-main sequence (PMS) to zero-age main sequence (ZAMS) spin up, prompt ZAMS spin down, and the early-main sequence (MS) convergence of surface rotation rates. We find the model parameters accounting for the slow and median rotators are very similar to each other, with a disk lifetime of 5 Myr and a core-envelope coupling timescale of 28−30 Myr. In contrast, fast rotators have both shorter disk lifetimes (2.5 Myr) and core-envelope coupling timescales (12 Myr). We show that a large amount of angular momentum is hidden in the radiative core for as long as 1 Gyr in these models and we discuss the implications for internal differential rotation and lithium depletion. We emphasize that these results are highly dependent on the adopted braking law. We also report a tentative correlation between the initial rotational period and disk lifetime, which suggests that protostellar spin down by massive disks in the embedded phase is at the origin of the initial dispersion of rotation rates in young stars. Conclusions. We conclude that this class of semi-empirical models successfully grasp the main trends of the rotational behavior of solar-type stars as they evolve and make specific predictions that may serve as a guide for further development.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/60effb1053a5fe87dd1f67170c200e7d47aa36a8

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In Astronomy and Astrophysics

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2. M. Marley
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Citations in the corpus

• MESA ISOCHRONES AND STELLAR TRACKS (MIST). I. SOLAR-SCALED MODELS (2016, background): “Second, current detailed evolutionary models (e.g., Bouvier 2008; Gallet & Bouvier 2013) suggest that low-mass stars (.”
• The Extreme Ultraviolet and X-Ray Sun in Time: High-Energy Evolutionary Tracks of a Solar-Like Star (2015, result): “As in previous studies (e.g. Gallet & Bouvier 2013), we constrain our rotation models by assuming that the percentilesof the rotational distributions for star clusters with different ages can be combined to estimate the time evolution of a star’s rotation rate.”
• THE MASS-DEPENDENCE OF ANGULAR MOMENTUM EVOLUTION IN SUN-LIKE STARS (2014, background): “Studies that included internal angular momentum transport (MacGregor & Brenner 1991; Gallet & Bouvier 2013; Charbonnel et al. 2013; Denissenkov 2010) indicate that internal differential rotation manifests as an increased spin-down at early times, followed by a convergence to- ward the solid-body…”
• ROTATION PERIODS OF 34,030 KEPLER MAIN-SEQUENCE STARS: THE FULL AUTOCORRELATION SAMPLE (2014, background): “In recent years there has also been considerable work towards understanding and modeling the underlying physics behind gyrochronology (Reiners & Mohanty 2012; Matt et al. 2012; Gallet & Bouvier 2013, and references therein).”
• Origin and evolution of the atmospheres of early Venus, Earth and Mars (2018, background): “The wide dispersion of Prot for young stars instead reflects the initial conditions for rotation starting after the protostellar disk phase (e.g., Gallet and Bouvier 2013).”
• Stellar winds on the main-sequence - II. The evolution of rotation and winds (2015, methodology): “…free parameter in their models and found that short coupling timescales of a few 10 Myr are required to reproduce the observational constraints (e.g. MacGregor & Brenner 1991; Spada et al. 2011; Gallet & Bouvier 2013), which leads to moderate differential rotation between the core and the envelope.”
• Determining stellar macroturbulence using asteroseismic rotational velocities from Kepler (2014, background): “The stellar rotation rate also depends on the star’s mass (Meibom et al. 2011) and thus it is a key parameter when studying stellar evolution (Ekström et al. 2012; Gallet & Bouvier 2013).”
• Stellar magnetism: empirical trends with age and rotation (2014, background): “For example, the relations 〈|BV |〉 versus t and 〈|BV |〉 versus Ro can be implemented in models investigating the evolution of mass and angular momentum loss (e.g., Gallet & Bouvier 2013).”
• The Gemini Planet Imager Exoplanet Survey: Giant Planet and Brown Dwarf Demographics from 10 to 100 au (2019, background): “Rotation of these stars can safely be ignored; observed v isin values are significantly lower than for early- type stars (Gallet & Bouvier 2013), and as such there is a negligible dependence of the effective temperature and surface gravity on stellar latitude.”