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Solar 5-min Oscillation Amplitude Anisotropy and Doppler Velocity Systematics

Published online by Cambridge University Press:  03 August 2017

J.R. Kuhn
Affiliation:
Physics Department, Princeton University, Princeton, N.J. USA
C.M. O'Neill
Affiliation:
Physics Department, Princeton University, Princeton, N.J. USA
L.B. Gilliam
Affiliation:
National Solar Observatory, NOAO, Sunspot, N.M. USA

Extract

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Several measurements of 5-min velocity amplitudes have yielded confusing and conflicting information on the l and m dependence of the modal excitation (Kuhn and O'hanlon, 1983 – henceforth KO; Deubner, 1985; and Hill et al. 1985). We have obtained considerably more data than was described in KO using similar observing techniques. Additional analysis has illuminated a systematic effect related to the finite spatial resolution, and line asymmetry of the data that can lead to errors in inferred velocity amplitudes. Even though Doppler shifts are calculated from the Fraunhofer line center positions the effect can lead to 5-min oscillation amplitude errors at the 10 percent or greater level. Line wing observations should be more susceptible, and comparable resolution 2-dimensional data may be less sensitive to this systematic.

Type
Chapter 1: Observations of Solar Oscillations
Copyright
Copyright © Reidel 1988 

References

Deubner, F.-L. Seismology of the Sun and Distant Stars (ed. Gough, D.O.) 83 (Reidel, Dordrecht, 1986).Google Scholar
Hill, F., Habor, D.A., Toomre, J. and November, L.H. Seismology of the Sun and Distant Stars (ed. Gough, D.O.) 85 (Reidel, Dordrecht, 1986).Google Scholar
Kuhn, J.R. and O'hanlon, M. Solar Physics, 87, 207 (1983).CrossRefGoogle Scholar