Lock-In Detection of Network-Driven Waves in the Corona
(JOP 52)

Instruments:
MDI, SUMER, UVCS, EIT
Coordinator:
Craig DeForest
Contacts:

Abstract

I hope to identify signatures of coherent wave motion on a five-minute time scale, or to reject the hypothesis that motion of the chromospheric network excites macroscopic waves that, in turn, heat the corona. Especially in light of recent developments, such as the measurement by UVCS of very high, mass dependent ``kinetic temperatures'' that may be associated with small scale, time dependent bulk flows; and such as SOHO observations of polar plumes, which appear to be relatively steady on a five-minute time scale and not to be heated by micro-impulsive events on arcsecond scales at their footpoints, there is a pressing need to investigate signatures of alfvén and other mechanical waves in the lower to mid corona.

The chief trade-off in measurements of wave motion in the lower to mid corona has been one of spectrometer slit width vs. exposure time: If a spectrometer slit is narrowed enough to provide the necessary spectral resolution to identify the doppler shifts from coronal wave motion, then the required exposure time to get good photon statistics precludes the measurement of dynamically changing doppler shifts as anything but a general line broadening.

By tracing a feature through the EIT field of view to the bottom of the corona, it should be possible to identify the network cell(s) associated with that feature's footpoint(s). If one hypothesizes that wave motion of the feature is being excited by network oscillations in the footpoint(s), then one may expect that the feature's spectrum will exhibit Doppler shifts with a particular time delay relationship to motions of the network at the footpoint(s).


Complete text of proposal.