scholarly journals The effects of surface fossil magnetic fields on massive star evolution – II. Implementation of magnetic braking in mesa and implications for the evolution of surface rotation in OB stars

2020 ◽  
Vol 493 (1) ◽  
pp. 518-535 ◽  
Author(s):  
Z Keszthelyi ◽  
G Meynet ◽  
M E Shultz ◽  
A David-Uraz ◽  
A ud-Doula ◽  
...  
Keyword(s):  
Angular Momentum ◽  
Magnetic Fields ◽  
Massive Star ◽  
Massive Stars ◽  
Rotation Rates ◽  
Momentum Loss ◽  
Star Models ◽  
Surface Rotation ◽  
Angular Momentum Loss ◽  
Magnetic Braking

ABSTRACT The time evolution of angular momentum and surface rotation of massive stars are strongly influenced by fossil magnetic fields via magnetic braking. We present a new module containing a simple, comprehensive implementation of such a field at the surface of a massive star within the Modules for Experiments in Stellar Astrophysics (mesa) software instrument. We test two limiting scenarios for magnetic braking: distributing the angular momentum loss throughout the star in the first case, and restricting the angular momentum loss to a surface reservoir in the second case. We perform a systematic investigation of the rotational evolution using a grid of OB star models with surface magnetic fields (M⋆ = 5–60 M⊙, Ω/Ωcrit = 0.2–1.0, Bp = 1–20 kG). We then employ a representative grid of B-type star models (M⋆ = 5, 10, 15 M⊙, Ω/Ωcrit = 0.2, 0.5, 0.8, Bp = 1, 3, 10, 30 kG) to compare to the results of a recent self-consistent analysis of the sample of known magnetic B-type stars. We infer that magnetic massive stars arrive at the zero-age main sequence (ZAMS) with a range of rotation rates, rather than with one common value. In particular, some stars are required to have close-to-critical rotation at the ZAMS. However, magnetic braking yields surface rotation rates converging to a common low value, making it difficult to infer the initial rotation rates of evolved, slowly rotating stars.

scholarly journals Angular momentum loss and stellar spin-down in magnetic massive stars

2008 ◽  
Vol 4 (S259) ◽  
pp. 423-424
Author(s):  
Asif ud-Doula ◽  
Stanley P. Owocki ◽  
Richard H.D. Townsend
Keyword(s):  
Angular Momentum ◽  
Massive Stars ◽  
Solid Angle ◽  
Magnetic Confinement ◽  
Dipole Field ◽  
Hot Stars ◽  
Momentum Loss ◽  
Dipole Magnetic Field ◽  
Angular Momentum Loss ◽  
Compare And Contrast

AbstractWe examine the angular momentum loss and associated rotational spin-down for magnetic hot stars with a line-driven stellar wind and a rotation-aligned dipole magnetic field. Our analysis here is based on our previous 2-D numerical MHD simulation study that examines the interplay among wind, field, and rotation as a function of two dimensionless parameters, W(=Vrot/Vorb) and ‘wind magnetic confinement’, η∗ defined below. We compare and contrast the 2-D, time variable angular momentum loss of this dipole model of a hot-star wind with the classical 1-D steady-state analysis by Weber and Davis (WD), who used an idealized monopole field to model the angular momentum loss in the solar wind. Despite the differences, we find that the total angular momentum loss averaged over both solid angle and time follows closely the general WD scaling ~ ṀΩR2A. The key distinction is that for a dipole field Alfvèn radius RA is significantly smaller than for the monopole field WD used in their analyses. This leads to a slower stellar spin-down for the dipole field with typical spin-down times of order 1 Myr for several known magnetic massive stars.

scholarly journals Asteroseismology and spectropolarimetry: opening new windows on the internal dynamics of massive stars

2014 ◽  
Vol 9 (S307) ◽  
pp. 420-425 ◽  
Author(s):  
S. Mathis ◽  
C. Neiner
Keyword(s):  
Angular Momentum ◽  
Magnetic Fields ◽  
Massive Star ◽  
State Of The Art ◽  
Massive Stars ◽  
The State ◽  
Internal Dynamics ◽  
Dynamical Processes ◽  
Internal Mixing ◽  
Mixing And Transport

AbstractIn this article, we show how asteroseismology and spectropolarimetry allow to probe dynamical processes in massive star interiors. First, we give a summary of the state-of-the-art. Second, we recall the MHD mechanisms that take place in massive stars. Next, we show how asteroseismology gives strong constraints on the internal mixing and transport of angular momentum while spectropolarimetry allows to unravel the role played by magnetic fields.

scholarly journals Evolution of rotation in rapidly rotating early-type stars during the main sequence with 2D models

2019 ◽  
Vol 625 ◽  
pp. A89 ◽  
Author(s):  
D. Gagnier ◽  
M. Rieutord ◽  
C. Charbonnel ◽  
B. Putigny ◽  
F. Espinosa Lara
Keyword(s):  
Angular Momentum ◽  
Mass Loss ◽  
Main Sequence ◽  
Massive Stars ◽  
Early Type ◽  
Wind Regime ◽  
Momentum Loss ◽  
Angular Momentum Loss ◽  
Rotational Evolution ◽  
Early Type Stars

The understanding of the rotational evolution of early-type stars is deeply related to that of anisotropic mass and angular momentum loss. In this paper, we aim to clarify the rotational evolution of rapidly rotating early-type stars along the main sequence (MS). We have used the 2D ESTER code to compute and evolve isolated rapidly rotating early-type stellar models along the MS, with and without anisotropic mass loss. We show that stars with Z = 0.02 and masses between 5 and 7 M⊙ reach criticality during the main sequence provided their initial angular velocity is larger than 50% of the Keplerian one. More massive stars are subject to radiation-driven winds and to an associated loss of mass and angular momentum. We find that this angular momentum extraction from the outer layers can prevent massive stars from reaching critical rotation and greatly reduce the degree of criticality at the end of the MS. Our model includes the so-called bi-stability jump of the Ṁ − Teff relation of 1D-models. This discontinuity now shows up in the latitude variations of the mass-flux surface density, endowing rotating massive stars with either a single-wind regime (no discontinuity) or a two-wind regime (a discontinuity). In the two-wind regime, mass loss and angular momentum loss are strongly increased at low latitudes inducing a faster slow-down of the rotation. However, predicting the rotational fate of a massive star is difficult, mainly because of the non-linearity of the phenomena involved and their strong dependence on uncertain prescriptions. Moreover, the very existence of the bi-stability jump in mass-loss rate remains to be substantiated by observations.

Angular Momentum Loss and the Origin of Cataclysmic Binaries

1976 ◽  
Vol 73 ◽  
pp. 209-212 ◽  
Author(s):  
Peter P. Eggleton
Keyword(s):  
Angular Momentum ◽  
Magnetic Fields ◽  
Stellar Wind ◽  
Orbital Motion ◽  
Tidal Friction ◽  
Momentum Loss ◽  
Cataclysmic Binaries ◽  
Short Period ◽  
Angular Momentum Loss ◽  
Two Stages

A two-stage mechanism is proposed whereby detached dwarf systems like V471 Tau may evolve into cataclysmic binaries. The two stages are (1) angular momentum loss from the secondary due to braking by a stellar wind linked with magnetic fields, and (2) angular momentum gain by the secondary from the orbital motion, due to tidal friction. This combination may be able to remove angular momentum from short-period binaries on a timescale of ~109 yr.

scholarly journals Rotation rates of massive stars in the Magellanic Clouds

2010 ◽  
Vol 6 (S272) ◽  
pp. 38-43
Author(s):  
Laura R. Penny ◽  
Douglas R. Gies
Keyword(s):  
Angular Momentum ◽  
Main Sequence ◽  
Massive Stars ◽  
Magellanic Clouds ◽  
Evolutionary Models ◽  
Rotation Rates ◽  
Angular Momentum Loss ◽  
Kolmogorov Smirnov ◽  
Statistical Results ◽  
Smirnov Test

AbstractWe present the results of our survey of the projected rotational velocities of 161 O-type stars in the Magellanic Clouds from archival FUSE observations. The evolved and unevolved samples from each environment are compared through the Kolmogorov-Smirnov test to determine if the distribution of equatorial rotational velocities is metallicity dependent for these massive objects. Stellar interior models predict that massive stars with SMC metallicity will have significantly reduced angular momentum loss on the main sequence compared to their Galactic counterparts. Our statistical results find some support for this prediction but also show that even at Galactic metallicity, evolved and unevolved massive stars have fairly similar fractions of stars with large V sin i. What is more compelling are the few evolved objects in the Magellanic Clouds with rotational velocities that approach or even exceed those predicted from the evolutionary models.

scholarly journals Mass-Loss From Spinning Stars

1980 ◽  
Vol 5 ◽  
pp. 601-613
Author(s):  
S. R. Sreenivasan
Keyword(s):  
Angular Momentum ◽  
Mass Loss ◽  
Massive Stars ◽  
Stellar Winds ◽  
Late Type ◽  
Momentum Loss ◽  
Adequate Understanding ◽  
Angular Momentum Loss ◽  
Evolutionary Consequences ◽  
Acceptable Theory

AbstractThe effects of mass-loss and angular momentum loss on the evolution of massive stars are discussed bringing out the main results as well as the limitations of recent studies. It is pointed out that an acceptable theory of stellar winds in early as well as late type stars is needed as well as a satisfactory assessment of a number of instabilities in these contexts for an adequate understanding of the evolutionary consequences for a wide variety of population I and polulation II stars, which are affected by mass-loss.

The Aging Solar Wind: a Break in Wind Evolution at Older Ages?

2017 ◽  
Vol 13 (S335) ◽  
pp. 98-101
Author(s):  
Dúalta Ó Fionnagáin ◽  
Aline A. Vidotto
Keyword(s):  
Solar Wind ◽  
Angular Momentum ◽  
Adverse Effects ◽  
Sharp Decline ◽  
X Ray ◽  
Rotation Rates ◽  
Momentum Loss ◽  
Angular Momentum Loss ◽  
Steep Decay

AbstractThe current solar wind is well studied from remote observations and in situ measurements. However, we have very little information of the solar wind as it has evolved. We investigate the evolution of the solar wind by modeling the winds of solar analogues. By using X-ray temperatures as proxies for wind temperatures, we find that a break in behaviour occurs. At 2 Gyr there is a sharp decline in coronal temperatures, which results in a steep decay in mass loss rates for older stars. As the wind is responsible for stellar spin down, through angular momentum loss due to magnetised winds, our results suggest a decline in angular momentum loss for older stars. This agrees with recent observations which find anomalously high rotation rates in older stars. We also find that this evolution in the wind has adverse effects on the Earth’s magnetosphere, with an Earth aged 100 Myr having a magnetosphere 3 Earth radii in size.

scholarly journals Angular Momentum Loss and the Formation of W UMa Systems

1983 ◽  
Vol 71 ◽  
pp. 465-468
Author(s):  
E. Budding
Keyword(s):  
Angular Momentum ◽  
Stellar Wind ◽  
Lagrangian Point ◽  
Contact Phase ◽  
Momentum Loss ◽  
Angular Momentum Loss ◽  
Type Contact ◽  
Contact Binaries ◽  
Magnetic Braking ◽  
Lines Of Force

Angular momentum loss (AML) may be introduced as part of the explanation of the peculiar overabundance of W UMa-type contact binaries (W UMS) (for a recent review, see Vilhu, 1981). Among the various possible mechanisms to achieve this are (i) overflow through the outer (L2) Lagrangian point in a deep contact phase (Kuiper, 1941; Nariai, 1979), (ii) magnetic braking, where magnetic lines of force “stiffen” and thus enhance the efficiency of angular momentum loss associated with a stellar wind (Huang, 1966; Mestel, 1968). Such subjects have been investigated in a number of more recent detailed studies.

scholarly journals Inferring the velocity of early massive stars from the abundances of extremely metal-poor stars

2019 ◽  
Vol 632 ◽  
pp. A62 ◽  
Author(s):  
Arthur Choplin ◽  
Nozomu Tominaga ◽  
Miho N. Ishigaki
Keyword(s):  
Velocity Distribution ◽  
Massive Star ◽  
Massive Stars ◽  
High Redshift ◽  
Chemical Enrichment ◽  
Rotation Rates ◽  
Star Models ◽  
Abundance Patterns ◽  
Low Metallicity ◽  
Stellar Models

Context. The nature of the early generation of massive stars can be inferred by investigating the origin of the extremely metal-poor (EMP) stars, likely formed from the ejecta of one or a few previous massive stars. Aims. We investigate the rotational properties of early massive stars by comparing the abundance patterns of EMP stars with massive stellar models including rotation. Methods. Low metallicity 20 M⊙ massive stellar models with eight initial rotation rates between 0 and 70% of the critical velocity are computed. Explosions with strong fallback are assumed. The ejected material is considered to fit individually the abundance patterns of 272 EMP stars with −4 <  [Fe/H] <  −3. Results. With increasing initial rotation, the [C/H], [N/H], [O/H], [Na/H], [Mg/H], and [Al/H] ratios in the massive star ejecta are gradually increased (up to ∼4 dex) while the 12C/13C ratio is decreased. Among the 272 EMP stars considered, ∼40 − 50% are consistent with our models. About 60 − 70% of the carbon-enhanced EMP star sample can be reproduced against ∼20 − 30% for the carbon-normal EMP star sample. The abundance patterns of carbon-enhanced EMP stars are preferentially reproduced with a material coming from mid to fast rotating massive stars. The overall velocity distribution derived from the best massive star models increases from no rotation to fast rotation. The maximum is reached for massive stars having initial equatorial velocities of ∼550 − 640 km s−1. Conclusions. Although subject to significant uncertainties, these results suggest that the rotational mixing operating in between the H-burning shell and the He-burning core of early massive stars played an important role in the early chemical enrichment of the Universe. The comparison of the velocity distribution derived from the best massive star models with velocity distributions of nearby OB stars suggests that a greater number of massive fast rotators were present in the early Universe. This may have important consequences for reionization, the first supernovae, or integrated light from high redshift galaxies.

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