2010A&A...519A..16H -
Astronomy and Astrophysics, volume 519, A16-16 (2010/9-1)
The GSF instability and turbulence do not account for the relatively low rotation rate of pulsars.
HIRSCHI R. and MAEDER A.
Abstract (from CDS):
We examine the effects of the horizontal turbulence in differentially rotating stars on the Goldreich-Schubert-Fricke (GSF) instability and apply our results to pre-supernova models. We derive the expression for the GSF instability with account of the thermal transport and smoothing of the µ-gradient by the horizontal turbulence. We apply the new expressions in numerical models of a 20 M☉ star. We show that if N2Ω<0 the Rayleigh-Taylor instability cannot be killed by the stabilising thermal and µ-gradients, so that the GSF instability is always there and we derive the corresponding diffusion coefficient. The GSF instability grows toward the very latest stages of stellar evolution. Close to the deep convective zones in pre-supernova stages, the transport coefficient of elements and angular momentum by the GSF instability can, in small parts of the star, be larger than the shear instability and even as large as the thermal diffusivity. However, the zones in which the GSF instability is acting are extremely narrow and there is not enough time left before the supernova explosion for a significant mixing to occur. Thus, the GSF instability remains insignificant for the evolution even when the inhibiting effects of the µ-gradient are reduced by the horizontal turbulence. We conclude that the GSF instability in pre-supernova stages is not responsible for the relatively low rotation rate of pulsars compared to the predictions of rotating star models.
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HS?
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Syntax of coordinates is : "ra dec (wtype) [error ellipse] quality bibcode" :
ra dec : right ascension and declination (unit and frame defined according to your Output Options)
Grey values are increasing the original precision due to the computation of frame transformations
(wtype) : wavelength class for the origin of the coordinates (Rad, mm, IR, Optical, UV, Xray, Gam)
[error ellipse] : measurement uncertainty, on (ra,dec) if the positional angle is 90 degrees, on (majaxis,minaxis) otherwise (in mas at defined epoch in the original catalogue),
position angle (in degrees North celestial pole to East)
quality : flag of quality
E ≥ 10"
D : 1-10" (and some old data)
C : 0.1-1"
B : 0.01-0.1" + 2MASS, Tyc
A : VLBI, Hipparcos
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FK4
coord.
(ep=B1950 eq=1950) :
00 50 53.0 -73 04 18
[
]
Syntax of coordinates is : "ra dec (wtype) [error ellipse] quality bibcode" :
ra dec : right ascension and declination (unit and frame defined according to your Output Options)
Grey values are increasing the original precision due to the computation of frame transformations
(wtype) : wavelength class for the origin of the coordinates (Rad, mm, IR, Optical, UV, Xray, Gam)
[error ellipse] : measurement uncertainty, on (ra,dec) if the positional angle is 90 degrees, on (majaxis,minaxis) otherwise (in mas at defined epoch in the original catalogue),
position angle (in degrees North celestial pole to East)
quality : flag of quality
E ≥ 10"
D : 1-10" (and some old data)
C : 0.1-1"
B : 0.01-0.1" + 2MASS, Tyc
A : VLBI, Hipparcos
bibcode : bibcode of the coordinates reference
Gal
coord.
(ep=J2000) :
302.8084 -44.3277
[
]
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References (10692 between 1850 and 2023) (Total 10692)
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