Are Stellar Rotational Axes Distributed Randomly?

Open Access
Publisher Website
Google Scholar
Abstract
Stellar line widths yield values of V sin i, but the equatorial rotational velocities, V, cannot be determined for individual stars without knowledge of their inclinations, i, relative to the lines of sight. For large numbers of stars we usually assume random orientations of rotational axes to derive mean values of V, but we wonder whether that assumption is valid. Individual inclinations can be derived only in special cases, such as for eclipsing binaries where they are close to 90° or for chromospherically active late-type dwarfs or spotted (e.g., Ap) stars where we have independent information about the rotational periods. We consider recent data on 102 Ap stars for which Catalano & Renson compiled rotational periods from the literature and Abt & Morrell (primarily) obtained measures of V sin i. We find that the rotational axes are oriented randomly within the measuring errors. We searched for possible dependence of the inclinations on Galactic latitude or longitude, and found no dependence.

This publication has 16 references indexed in Scilit: