The Acoustic Cutoff Frequency of the Sun and the Solar Magnetic Activity Cycle

Jiménez, A.; García, R. A.; Pallé, P. L.
Referencia bibliográfica

The Astrophysical Journal, Volume 743, Issue 2, article id. 99 (2011).

Fecha de publicación:
12
2011
Número de autores
3
Número de autores del IAC
2
Número de citas
32
Número de citas referidas
27
Descripción
The acoustic cutoff frequency—the highest frequency for acoustic solar eigenmodes—is an important parameter of the solar atmosphere as it determines the upper boundary of the p-mode resonant cavities. At frequencies beyond this value, acoustic disturbances are no longer trapped but are traveling waves. Interference among them gives rise to higher-frequency peaks—the pseudomodes—in the solar acoustic spectrum. The pseudomodes are shifted slightly in frequency with respect to p-modes, making possible the use of pseudomodes to determine the acoustic cutoff frequency. Using data from the GOLF and VIRGO instruments on board the Solar and Heliospheric Observatory spacecraft, we calculate the acoustic cutoff frequency using the coherence function between both the velocity and intensity sets of data. By using data gathered by these instruments during the entire lifetime of the mission (1996 until the present), a variation in the acoustic cutoff frequency with the solar magnetic activity cycle is found.
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Savita
Mathur