Are short-term variations in solar oscillation frequencies the signature of a second dynamo? |
Auteur | Broomhall Anne-Marie |
Institution | University of Birmingham |
Theme | Solar diameter, irradiance and activity |
| Auteur(s) supplémentaire(s) | Stephen.T. Fletcher (2), David Salabert (3), Sarbani Basu (4), William J. Chaplin (1), Yvonne Elsworth (1), Rafa A. García (5), Antonio Jimenez (3), and Roger New (2) |
| Institution(s) supplémentaire(s) | (2) Sheffield Hallam University, (3) Instituto de Astrofisica de Canarias, (4) Yale University, (5) Service d'Astrophysique, CEA/Sacaly |
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Abstract | In addition to the well-known 11-year solar cycle, the Sun’s magnetic activity also shows significant variation on shorter time scales, e.g. between one and two years. We observe a quasi-biennial (2-year) signal in the solar p-mode oscillation frequencies, which are sensitive probes of the solar interior. The signal is visible in Sun-as-a-star data observed by different instruments and here we describe the results obtained using BiSON, GOLF, and VIRGO data. Our results imply that the 2-year signal is susceptible to the influence of the main 11-year solar cycle. However, the source of the signal appears to be separate from that of the 11-year cycle. We speculate as to whether it might be the signature of a second dynamo, located in the region of near-surface rotational shear. |
