Angular momentum transport efficiency in post-main sequence low-mass stars

AbstractOur current understanding and modeling of angular momentum transport in low-mass stars are briefly reviewed. Emphasis is set on single stars slightly younger that the Sun and on subgiants and red giants observed by the space missionsCoRoTandKepler.

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Evidence of angular momentum transport in main-sequence solar-like stars

Proceedings of the International Astronomical Union ◽

10.1017/s174392131600627x ◽

2015 ◽

Vol 11 (A29B) ◽

pp. 661-666

Author(s):

Othman Benomar ◽

Masao Takata ◽

Hiromoto Shibahashi ◽

Tugdual Ceillier ◽

Rafael A. García

Keyword(s):

Angular Momentum ◽

Rotation Rate ◽

Main Sequence ◽

Light Variation ◽

Momentum Transport ◽

Angular Momentum Transport ◽

Surface Rotation ◽

Average Rotation ◽

The Difference ◽

Few Data

AbstractThe rotation rates in the interior and at the surface is determined for the 22 main-sequence stars with masses between 1.0 and 1.6 M⊙. The average interior rotation is measured using asteroseismology, while the surface rotation is measured by the spectroscopic v sin i or the periodic light variation due to surface structures, such as spots. It is found that the difference between the surface rotation rate determined by spectroscopy and the average rotation rate for most of stars is small enough to suggest that an efficient process of angular momentum transport operates during and/or before the main-sequence stage of stars. By comparing the surface rotation rate measured from the light variation with those measured by spectroscopy, we found hints of latitudinal differential rotation. However, this must be confirmed by a further study because our result is sensitive to a few data points.

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Angular momentum transport in pre-main-sequence stars of intermediate mass

Solar Physics ◽

10.1007/bf00154165 ◽

1990 ◽

Vol 128 (1) ◽

pp. 287-298 ◽

Cited By ~ 16

Author(s):

C. Vigneron ◽

A. Mangeney ◽

C. Catala ◽

E. Schatzman

Keyword(s):

Angular Momentum ◽

Main Sequence ◽

Momentum Transport ◽

Main Sequence Stars ◽

Intermediate Mass ◽

Angular Momentum Transport

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Tidally–Induced Angular Momentum Transport in Disks

Symposium - International Astronomical Union ◽

10.1017/s0074180900225461 ◽

2001 ◽

Vol 200 ◽

pp. 406-409 ◽

Cited By ~ 2

Author(s):

Caroline E. J. M. L. J. Terquem

Keyword(s):

Angular Momentum ◽

Main Sequence ◽

Dominant Role ◽

Momentum Transport ◽

Tidal Effects ◽

Mhd Turbulence ◽

Angular Momentum Transport ◽

Tidal Waves ◽

Protostellar Disks ◽

Bending Waves

We discuss the transport of angular momentum induced by tidal effects in a disk surrounding a star in a pre–main sequence binary system. We consider the effect of both density and bending waves. Although tidal effects are important for truncating protostellar disks and for determining their size, it is unlikely that tidally–induced angular momentum transport plays a dominant role in the evolution of protostellar disks. Where the disk is magnetized, transport of angular momentum is probably governed by MHD turbulence. In a non self–gravitating laminar disk, the amount of transport provided by tidal waves is probably too small to account for the lifetime of protostellar disks. In addition, tidal effects tend to be localized in the disk outer regions.

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First grids of low-mass stellar models and isochrones with self-consistent treatment of rotation

Astronomy and Astrophysics ◽

10.1051/0004-6361/201935160 ◽

2019 ◽

Vol 631 ◽

pp. A77 ◽

Cited By ~ 18

Author(s):

L. Amard ◽

A. Palacios ◽

C. Charbonnel ◽

F. Gallet ◽

C. Georgy ◽

...

Keyword(s):

Angular Momentum ◽

Open Clusters ◽

Momentum Transport ◽

Surface Boundary ◽

Angular Momentum Transport ◽

Solar Composition ◽

Self Consistent ◽

Low Mass ◽

Stellar Models ◽

The Impact

Aims.We present an extended grid of state-of-the art stellar models for low-mass stars including updated physics (nuclear reaction rates, surface boundary condition, mass-loss rate, angular momentum transport, rotation-induced mixing, and torque prescriptions). We evaluate the impact of wind braking, realistic atmospheric treatment, rotation, and rotation-induced mixing on the structural and rotational evolution from the pre-main sequence (PMS) to the turn-off.Methods.Using the STAREVOL code, we provide an updated PMS grid. We computed stellar models for seven different metallicities, from [Fe/H] = −1 dex to [Fe/H] = +0.3 dex with a solar composition corresponding toZ = 0.0134. The initial stellar mass ranges from 0.2 to 1.5M⊙with extra grid refinement around one solar mass. We also provide rotating models for three different initial rotation rates (slow, median, and fast) with prescriptions for the wind braking and disc-coupling timescale calibrated on observed properties of young open clusters. The rotational mixing includes the most recent description of the turbulence anisotropy in stably stratified regions.Results.The overall behaviour of our models at solar metallicity, and their constitutive physics, are validated through a detailed comparison with a variety of distributed evolutionary tracks. The main differences arise from the choice of surface boundary conditions and initial solar composition. The models including rotation with our prescription for angular momentum extraction and self-consistent formalism for angular momentum transport are able to reproduce the rotation period distribution observed in young open clusters over a wide range of mass values. These models are publicly available and can be used to analyse data coming from present and forthcoming asteroseismic and spectroscopic surveys such asGaia, TESS, and PLATO.

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The rotational evolution of young low mass stars

Proceedings of the International Astronomical Union ◽

10.1017/s1743921307009593 ◽

2007 ◽

Vol 3 (S243) ◽

pp. 231-240 ◽

Cited By ~ 9

Author(s):

Jérôme Bouvier

Keyword(s):

Angular Momentum ◽

Accretion Disk ◽

Main Sequence ◽

Young Stars ◽

Sequence Evolution ◽

Main Sequence Stars ◽

Low Mass Stars ◽

Rotational Evolution ◽

Low Mass

AbstractStar-disk interaction is thought to drive the angular momentum evolution of young stars. In this review, I present the latest results obtained on the rotational properties of low mass and very low mass pre-main sequence stars. I discuss the evidence for extremely efficient angular momentum removal over the first few Myr of pre-main sequence evolution and describe recent results that support an accretion-driven braking mechanism. Angular momentum evolution models are presented and their implication for accretion disk lifetimes discussed.

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Effect of partial mixing of matter on the hydrodynamic angular momentum transport processes in massive main-sequence stars

Astronomy Letters ◽

10.1134/s1063773709060073 ◽

2009 ◽

Vol 35 (6) ◽

pp. 413-423 ◽

Cited By ~ 5

Author(s):

E. I. Staritsin

Keyword(s):

Angular Momentum ◽

Main Sequence ◽

Transport Processes ◽

Momentum Transport ◽

Main Sequence Stars ◽

Angular Momentum Transport

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Main Sequence Angular Momentum Loss in Low-Mass Stars

Angular Momentum Evolution of Young Stars ◽

10.1007/978-94-011-3580-1_14 ◽

1991 ◽

pp. 151-165 ◽

Cited By ~ 3

Author(s):

David R. Soderblom

Keyword(s):

Angular Momentum ◽

Main Sequence ◽

Low Mass Stars ◽

Momentum Loss ◽

Angular Momentum Loss ◽

Low Mass

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The s process in AGB stars as constrained by a large sample of barium stars

Astronomy and Astrophysics ◽

10.1051/0004-6361/201834079 ◽

2018 ◽

Vol 620 ◽

pp. A146 ◽

Cited By ~ 13

Author(s):

B. Cseh ◽

M. Lugaro ◽

V. D’Orazi ◽

D. B. de Castro ◽

C. B. Pereira ◽

...

Keyword(s):

Angular Momentum ◽

Transport Mechanism ◽

Momentum Transport ◽

Element Abundance ◽

Agb Stars ◽

Primary Star ◽

Angular Momentum Transport ◽

Giant Stars ◽

Low Mass ◽

Process Elements

Context. Barium (Ba) stars are dwarf and giant stars enriched in elements heavier than iron produced by the slow neutron-capture process (s process). These stars belong to binary systems in which the primary star evolved through the asymptotic giant branch (AGB) phase. During this phase the primary star produced s-process elements and transferred them onto the secondary, which is now observed as a Ba star. Aims. We compare the largest homogeneous set of Ba giant star observations of the s-process elements Y, Zr, La, Ce, and Nd with AGB nucleosynthesis models to reach a better understanding of the s process in AGB stars. Methods. By considering the light-s (ls: Y and Zr) heavy-s (hs: La, Ce, and Nd) and elements individually, we computed for the first time quantitative error bars for the different hs-element to ls-element abundance ratios, and for each of the sample stars. We compared these ratios to low-mass AGB nucleosynthesis models. We excluded La from our analysis because the strong La lines in some of the sample stars cause an overestimation and unreliable abundance determination, as compared to the other observed hs-type elements. Results. All the computed hs-type to ls-type element ratios show a clear trend of increasing with decreasing metallicity with a small spread (less than a factor of 3). This trend is predicted by low-mass AGB models in which 13C is the main neutron source. The comparison with rotating AGB models indicates the need for the presence of an angular momentum transport mechanism that should not transport chemical species, but significantly reduces the rotational speed of the core in the advanced stellar evolutionary stages. This is an independent confirmation of asteroseismology observations of the slow down of core rotation in giant stars, and of rotational velocities of white dwarfs lower than predicted by models without an extra angular momentum transport mechanism.

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