Evaluating variation corrected SOT/Hinode CaII H sequence off-limb spicules

The theory of coronal heating and solar wind due to photospheric fluctuations is strengthened by the existence of coherency up to the transition region. The coherency of solar spicules intensity Oscillations with increasing height above the solar limb in quiet Sun was explored using the Solar Optical Telescope (SOT) on the HINODE spacecraft. Using time sequences near the equatorial region with a cadence of ۸ s from the HINODE/SOT in Ca II H line with broadband filter obtained on ۲۲ November ۲۰۰۶. A deconvolution procedure was applied to the spicules to illustrate how effective our restoration method works on fine structures such as spicules. After applying the correction, the normalized rms (root mean square) contrast was typically ۰.۲۱ before correction (for processed image) and it was ۰.۳۴ after correction (deconvolved image), which is a factor of ۱.۶۱ higher than those obtained before PSF deconvolution. The intensity oscillations at different heights above the solar limb were analyzed by Fourier and wavelet transforms. Then the phase difference among oscillations at two certain heights for evidence of coherent oscillations was measured. The results of fast Fouriertransform (FFT) show dominant frequency peaks ۳.۵ mHz, ۵.۵ mHz, and ۸ mHz at four separate heights. The wavelet results indicate frequencies similar to FFT results. The dominant frequency for coherency of more than ۷۵% level shows about ۳.۵ mHz and ۵.۸ mHz frequencies. The mean phase speeds of ۱۷۵-۳۰۰ kms-۱ were measured and it was found that the mean phase speeds increase was along with its height. And also, strong evidence is achieved for upwardly propagating coherent waves.

کلیدواژه ها:

Quiet Sun ، solar spicules ، stray light ، image processing ، oscillations ، coherency.