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A Statistical Treatment of the Stellar Rotational Velocities Which Considers the Break-Up Limit

Published online by Cambridge University Press:  12 April 2016

P. L. Bernacca
P. L. Bernacca*
Affiliation:
Asiago Astrophysical Observatory, University of Padua, Italy

Abstract

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This paper develops a new statistical approach to the study of the axial rotational velocities of the stars, by considering the break-up limit or any upper limit for the equatorial rotational velocities. The main conclusions are as follows: (1) For random orientation of the axis of rotation, the frequency function of the inclination α to the line of sight is not sina, as assumed until now. (2) For stars with the same break-up velocity vb, the distribution of α is given by :

where f(y) is the distribution of the apparent velocities y = v sin α, v being the true rotational velocity. New integral equations governing the frequency function of α, y and v have been derived and the correct procedure to treat observations has been discussed; a simple method is also suggested to get an approximate trend of the distribution of the true velocities directly from the observed histogram. The method of analysis proposed in this paper has been applied to a re-discussion of the rotational behaviour of a group of Be stars.

Type
Part III / Stellar Rotation in Binaries, Clusters, and Special Objects. Statistics of Stellar Rotation
Information
International Astronomical Union Colloquium , Volume 4: Stellar Rotation , 1970 , pp. 227 - 248
Copyright
Copyright © Reidel 1970

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