On the dipolar f mode of stellar oscillation |
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| Authors: | J Christensen-Dalsgaard DO Gough |
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| Institution: | 1Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Cambridge;2Teoretisk Astrofysik Center, Danmarks Grundforskningsfond, and Institut for Fysik og Astronomi, Aarhus Universitet, DK-8000 Aarhus C, Denmark;3Institute of Astronomy, University of Cambridge, Cambridge CB3 0HA |
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| Abstract: | The classification of adiabatic modes of non-radial stellar oscillation was established by Cowling in 1941. In addition to acoustic and gravity modes he identified an intermediate mode, which he labelled the f mode, and which in simple stellar models has no radial node. The motion of a dipolar f mode (of spherical-harmonic degree l =1) shifts the centre of mass, and must have zero frequency. On the other hand, if the perturbation to the gravitational potential is neglected (the case considered by Cowling) the f mode has a frequency intermediate between those of the gravity and acoustic modes; this is true of modes of any degree ( l ≥1) . Here we consider the properties of the dipolar f mode, elucidating the origin of these differences through continuous transformations between the various relevant cases; in addition, we discuss the broader issues of the classification of modes of non-radial oscillation. |
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| Keywords: | stars: oscillations |
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