EVOLUTION OF ROTATIONAL VELOCITIES OF A-TYPE STARS

The equatorial velocity of A-type stars undergoes an acceleration in the first third of the main sequence (MS) stage, but the velocity decreases as if the stars were not undergoing any redistribution of angular momentum in the external layers in the last stage of the MS phase. Our calculations show...

Full description

Saved in:
Bibliographic Details
Published in:Astrophysical journal. Letters 2013-03, Vol.765 (2), p.1-5, Article L36
Main Authors: Yang, Wuming, BI, SHAOLAN, MENG, XIANGCUN, Tian, Zhijia
Format: Article
Language:English
Subjects:
ACCELERATION
Age
ANGULAR MOMENTUM
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
Constants
Density
Differential rotation
Envelopes
EXPANSION
LAYERS
ROTATION
Slopes
STAR EVOLUTION
STARS
VELOCITY
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:The equatorial velocity of A-type stars undergoes an acceleration in the first third of the main sequence (MS) stage, but the velocity decreases as if the stars were not undergoing any redistribution of angular momentum in the external layers in the last stage of the MS phase. Our calculations show that the acceleration and the decrease of the equatorial velocity can be reproduced by the evolution of the differential rotation zero-age MS model with the angular momentum transport caused by hydrodynamic instabilities during the MS stage. The acceleration results from the fact that the angular momentum stored in the interiors of the stars is transported outward. In the last stage, the core and the radiative envelope are uncoupling, and the rotation of the envelope is a quasi-solid rotation; the uncoupling and the expansion of the envelope indicate that the decrease of the equatorial velocity approximately follows the slope for the change in the equatorial velocity of the model without any redistribution of angular momentum. When the fractional age 0.3 [
ISSN:0004-637X
2041-8205
1538-4357
2041-8213
DOI:10.1088/2041-8205/765/2/L36