Short Time-Scale Variability in the Light Curve of~TW~Draconis

We have re-analyzed old photometric UBV data obtained by Papoušek et al. at Skalnaté Pleso, Slovakia (1967–1980) and Brno, Czech Republic (1976–1979) observatories and analyzed new own CCD measurements (Brno, 2003–2005). In both set of photometric data the oscillations in the vicinity of the primary minimum were found. The detected periods are compatible with the previously published ones.     

Two-dimensional spectroscopic time series of solar granulation

In this paper we investigate the dynamics of the solar granulation by analyzing time series of 2D spatially highly resolved spectrograms. These were obtained by spatial scans covering a field of 12 8″ × 20″. The advantage of this method is a high spectral resolution, however, the data are not taken simultaneously and to cover the field described above 50 exposures taken sequentially in time are necessary. Therefore, to obtain one map about 2 minutes are required. Plots of the evolution of different line parameters are given as well as the decay of correlation functions. The correlations between the first map of line parameters and successive maps (which are separated by about 2 minutes) were investigated showing a rapid decay down to a correlation coefficient of 0.4 within 4 minutes, the velocity pattern in the field observed varies on smaller time scales. The temporal variation of correlation between the line parameters for the different lines shows a periodic signal related to 5-min oscillations which could not be totally filtered. The evolution of the correlation functions between line parameters is analyzed which gives an error estimate of all correlation values found in the literature. For the first time it is explicitly shown how evolution in a selected photospheric field influences the evolution of granular/intergranular structures.