Low-degree, ℓ = 4 modes in full-disc BiSON⋆ helioseismological data
Open Access
- 11 June 1996
- journal article
- Published by Oxford University Press (OUP) in Monthly Notices of the Royal Astronomical Society
- Vol. 280 (4) , 1162-1166
- https://doi.org/10.1093/mnras/280.4.1162
Abstract
We demonstrate that some ℓ = 4 acoustic eigenmodes of the Sun are clearly distinguishable in long power spectra generated from Doppler velocity residuals collected in unimaged sunlight by the six-station Birmingham Solar Oscillations Network (BiSON). Modes covering the range n = 17 to 21 have been measured in 16-month-long power spectra. They have typical amplitudes — when measured in full-disc Doppler velocity data — of less than ∼ 1 cm s−1 per root bin, and their frequencies have been determined to fractional accuracies of the order of 3 parts in 105. The sensitivity of the whole-disc observations to these modes — as implied by the data — appears to be approximately a factor of 2 greater than the theoretical predictions of Christensen-Dalsgaard.Keywords
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