Solar activity cycle and rotation of the corona
| Autor: | Z. Mouradian, C. Botton, R. Bocchia |
|---|---|
| Přispěvatelé: | Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Physique solaire, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris |
| Jazyk: | angličtina |
| Rok vydání: | 2002 |
| Předmět: | |
| Zdroj: | Astronomy and Astrophysics-A&A Astronomy and Astrophysics-A&A, 2002, 394, pp.1103-1109. ⟨10.1051/0004-6361:20021244⟩ |
| ISSN: | 0004-6361 |
| Popis: | In this paper we consider the dependence of the coronal rotation period on solar activity. We analyzed the 10.7 cm radio emission flux covering cycles 19 to 22. We have established a new method for studying the rotation rate: by identifying the flux pulses with the recurrence of active longitudes. We first determined the frequency domain of the rotation and then analyzed each cycle separately. The entire domain of 51.7 years was divided into 480-day sections, which were analyzed independently and then grouped into frames for each cycle in order to study the time variation of prominent frequencies (Fig. 4). Power spectra were obtained with the Maximum Entropy Method. The 10.7 cm emission rotation varies accordingly to the activity level, i.e. at the activity maxima the synodic period of rotation is about 25.4 days and at the minima it is around 30 days; it is 32 days for the quiet Sun (Table 1). Empirical relations give the ratio of maximum and minimum sidereal rotation rate with respect to sunspot number (Fig. 6). During the cycle increase phase, the average acceleration of the rotation period is 0.8°/d per year, in decreasing phase that average is only -0.5. |
| Databáze: | OpenAIRE |
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