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SANTIAGO 91, a right ascension catalogue of 3387 stars (equinox J2000).
The positions in right ascension of 3387 stars belonging to the Santiago67 Catalogue, observed with the Repsold Meridian Circle at Cerro Calan,National Astronomical Observatory, during the period 1989 to 1994, aregiven. The average mean square error of a position, for the wholeCatalogue, is +/-0.009 s. The mean epoch of the catalogue is 1991.84.
| Evidences for a bifurcation in massive star evolution. The ON-blue stragglers
The effects of rotationally induced mixing on the evolution of massivestars is examined. The mechanism considered results from baroclinicinstability due to differential rotation which produces two-dimensionalmeteorological-like turbulent motions; the mixing is produced by thesmall-scale three-dimensional tail of the turbulent spectrum. The modelsshow that, due to the high viscosity, the diffusion coefficient would besufficiently large to mix most massive stars during their MS lifetime.However, below some critical rotation velocity, diffusive mixing isefficiently prevented by the mu-gradient. Below critical rotiation, theevolution is essentially classical with unmodifed redwards tracks in theHR diagram. Above critical rotation, the evolutionary tracks go upwardsand bluewards, very close to those of fully homogeneous evolution.Comparisons with observations indicate that turbulent diffusion canaccount for the ON stars lying close to the zero-age sequence.
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