Rapid Fluctuations in the Lower Solar Atmosphere
Abstract
The Rapid Oscillations in the Solar Atmosphere instrument reveals solar atmospheric fluctuations at high frequencies. Spectra of variations of the G-band intensity (IG ) and Ca II K-line intensity (IK ) show correlated fluctuations above white noise to frequencies beyond 300 mHz and 50 mHz, respectively. The noise-corrected G-band spectrum for f = 28-326 mHz shows a power law with exponent -1.21 ± 0.02, consistent with the presence of turbulent motions. G-band spectral power in the 25-100 mHz ("UHF") range is concentrated at the locations of magnetic bright points in the intergranular lanes and is highly intermittent in time. The intermittence of the UHF G-band fluctuations, shown by a positive kurtosis κ, also suggests turbulence. Combining values of IG , IK , UHF power, and κ reveals two distinct states of the solar atmosphere. State 1, including almost all the data, is characterized by low IG , IK , and UHF power and κ ≈ 6. State 2, including only a very small fraction of the data, is characterized by high IG , IK , and UHF power and κ ≈ 3. Superposed epoch analysis shows that the UHF power peaks simultaneously with spatio-temporal IG maxima in either state. For State 1, IK shows 3.5 minute chromospheric oscillations with maxima occurring 21 s after IG maxima implying a 150-210 km effective height difference. However, for State 2 the IK and IG maxima are simultaneous; in this highly magnetized environment sites of G-band and K-line emission may be spatially close together.
- Publication:
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The Astrophysical Journal
- Pub Date:
- December 2011
- DOI:
- 10.1088/2041-8205/743/1/L24
- arXiv:
- arXiv:1111.4253
- Bibcode:
- 2011ApJ...743L..24L
- Keywords:
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- Sun: chromosphere;
- Sun: oscillations;
- Sun: photosphere;
- Astrophysics - Solar and Stellar Astrophysics
- E-Print:
- Accepted by Astrophysical Journal Letters