| Autor: |
Goddard, C. R., Birch, A. C., Fournier, D., Gizon, L. |
| Rok vydání: |
2020 |
| Předmět: |
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| Zdroj: |
A&A 640, L10 (2020) |
| Druh dokumentu: |
Working Paper |
| DOI: |
10.1051/0004-6361/202038539 |
| Popis: |
Context. Large-scale equatorial Rossby modes have been observed on the Sun over the last two solar cycles. Aims. We investigate the impact of the time-varying zonal flows on the frequencies of Rossby modes. Methods. A first-order perturbation theory approach is used to obtain an expression for the expected shift in the mode frequencies due to perturbations in the internal rotation rate. Results. Using the time-varying rotation from helioseismic inversions we predict the changes in Rossby mode frequencies with azimuthal orders from m = 1 to m = 15 over the last two solar cycles. The peak-to-peak frequency change is less than 1 nHz for the m = 1 mode, grows with m, and reaches 25 nHz for m = 15. Conclusions. Given the observational uncertainties on mode frequencies due to the finite mode lifetimes, we find that the predicted frequency shifts are near the limit of detectability. |
| Databáze: |
arXiv |
| Externí odkaz: |
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