SIGNATURES OF ACOUSTIC AND MAGNETIC WAVES IN SOLAR AND STELLAR CORONAE

Time-dependent dynamical calculations of the radiating gas in solar co ronal flux tubes are used to identify features of UV spectral-line pro files that can reveal the direction in which wave energy flows through the solar transition region. The profile features survive spatial and temporal averaging through nonlinear dependencies of line emission co efficients on thermal properties of the plasma that are correlated wit h fluid velocities. This approach can be applied to stellar and other unresolved sources, as well as the solar atmosphere. It can be regarde d as a new angle of attack on the long-standing problem of determining coronal heating mechanisms. The approach requires low noise data of h igh spectral resolution. Therefore, it can take advantage of some uniq ue properties of the SUMER instrument on SOHO. We make specific predic tions for SUMER data that, in principle, can test whether energy propa gates upward or downward in coronal flux tubes, thus allowing one to d iscriminate between competing theories of coronal heating. We are acqu iring SUMER data in an attempt to do this.