Introduction
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The rapid rise of plasma temperature up to 1 MK from the solar photosphere towards the corona is still an unresolved problem in solar physics. It is clear that the mechanical energy of sub-photospheric motions is transported somehow into the upper solar atmosphere, where it may be dissipated leading to the heating of the ambient plasma. A possible scenario of energy transport is that the convective motions and solar global oscillations may excite magnetohydrodynamic (MHD) waves in the photosphere, which may then propagate through the chromosphere carrying relevant energy into the corona.
Spicules are grass-like spiky features best seen in chromospheric spectral lines at the solar limb. Beside the morphological and global dynamic studies there are early observational reports on oscillatory phenomena in spicules. However, only a limited number of studies have addressed spicule oscillations with recent high-resolution ground and space-based observations. It is strongly anticipated that signatures of the energy transport by MHD waves through the chromosphere may be detectable in the oscillatory dynamics of spicules. A comprehensive novel observational study of waves and oscillations in spicules, to the best of our knowledge, is still lacking and such observational campaign could clarify important details of the magnetic coupling from the photosphere to corona.
We plan to use existing Hinode, SoHO & TRACE sequences, in addition to acquiring high-cadence ROSA & IBIS data (weather permitting). What is the relationship between spicules, macrospicules and Jets as seen in the TR and corona? Why are spicules as seen in ARs of shorter duration? Does this imply a different heating mechanism? How do spicules manifest themselves in the TR and corona?
Primary Objectives
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The primary objective of this proposal is not only to study the dynamic activity in the lower solar atmosphere but to trace that activity to the TR and corona.
Our observing setup will allow us to identify oscillatory power (via FWHM oscillations) in velocity and intensity with frequencies in excess of 20mHz. With XRT and EIS, we will acquire images and spectral data to enable a determination of the flow, temperatures and electron density structure in the upper atmosphere. SOT will provide magnetograms in Na D I, Ca II K and if possible H alpha line center and wing emission.
TRACE will provide high-cadence observations with the 171 A filter. SUMER will provide high spectral resolution for selected transition region lines providing a diagnostic of the flow structure. |
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