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Is It Possible to Determine Whether a Star is Rotating About a Unique Axis?

Published online by Cambridge University Press:  12 April 2016

D.O. Gough  and
A.G. Kosovichev
D.O. Gough
Affiliation:
Institute of Astronomy, Madingley Road, Cambridge CB3 OHA, England
A.G. Kosovichev
Affiliation:
Institute of Astronomy, Madingley Road, Cambridge CB3 OHA, England

Extract

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Rotating stars are normally presumed to rotate about a unique axis. Would it be possible to determine whether or not that presumption is correct? This is a natural question to raise, particularly after the suggestion by T. Bai & P. Sturrock that the core of the sun rotates about an axis that is inclined to the axis of rotation of the envelope.

A variation with radius of the direction of the rotation axis would modify the form of rotational splitting of oscillation eigenfrequencies. But so too does a variation with depth and latitude in the magnitude of the angular velocity. One type of variation can mimic the other, and so frequency information alone cannot differentiate between them. What is different, however, is the structure of the eigenfunctions. Therefore, in principle, one might hope to untangle the two phenomena using information about both the frequencies and the amplitudes of the oscillations.

We consider a simple model of a star which is divided into two regions, each of which is rotating about a different fixed axis. We enquire whether there are any circumstances under which it might be possible to determine seismologically the separate orientations of the axes.

Type
VI. Asteroseismology: theory
Information
International Astronomical Union Colloquium , Volume 137: Inside the Stars , 1993 , pp. 566 - 568
Copyright
Copyright © Astronomical Society of the Pacific 1993

References

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Gough, D.O. & Kosovichev, A.G. 1992, Mon.Not.R.astr.Soc. (in preparation)Google Scholar
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