Lower Solar Chromosphere Research Articles

Radiation loss and mechanical heating in the low solar chromosphere

We discuss Ulmschneider's claim to have established that the short-period acoustic wave energy input is the only one able to balance the chromospheric radiation loss. We first review the range of uncertainty in empirical and radiative equilibrium models, on which estimates of the excess radiation coming from mechanical heating rest. We then show that Ulmschneider's estimate of this excess radiation from such models uses an over-simplified computational method. The resultant of uncertainty in models and in computational methods suggests that Ulmschneider's results on excess radiation from heating in the low chromosphere is subject to overestimation by an order of magnitude.

The effect of two-dimensional macroscopic velocity fields on models of the lower solar chromosphere

Two-dimensional macroscopic velocity fields are featured in the calculation of two-dimensional models of the lower solar chromosphere. Relative rms line centre intensity fluctuation data and mean limb darkening data obtained in Mg b and Na D are used together with values of the cross-correlation between line centre brightness and ‘line of sight velocities’. It is found that the large scale fluctuation data can be explained by models of the lower solar chromosphere in which the inhomogeneous effects arise only from horizontal, two-dimensional macroscopic velocity fields. It is also shown, however, that the corresponding small scale fluctuation data cannot be explained in a similar manner. The cross-correlation data is found to be a powerful constraint in the computation of two-dimensional models of these regions.

Calculations of two-dimensional models of the lower solar chromosphere

Several two-dimensional models of the lower solar chromosphere are computed using relative RMS line centre intensity variations and mean limb darkening curves observed in Mg b and NaD. These calculations indicate that the small scale fluctuations observed at line centre in these lines may result from density and electron temperature fluctuations in the lower chromosphere, while the large scale fluctuations may result from either fluctuations in the deeper lying continuum or horizontal and vertical differential velocity fields.

The Effect of the Density Scale Height on Shock-Wave Heating in the Low Solar Chromosphere

The Effect of the Density Scale Height on Shock-Wave Heating in the Low Solar Chromosphere