Line-of-sight Velocity in a Semiempirical Model of a Disappearing Granule

The behaviour of the line-of-sight velocity in the centre of a disappearing granule is analyzed using an inversion method applied to a time-series of spectra containing the Fe I 522.5 nm, 557.6 nm and 557.7 nm lines. The temporal evolution of the line-of-sight velocity vLOS is presented in the form of the functional dependence of vLOS(log o/5, t) on the optical depth at 500 nm and time. An oscillatory behaviour is found in the velocity stratification with nearly constant phase through the photosphere. The amplitude of variations increases from log depth = -0.3 to log depth = -2.5 reaching a maximum of 1.2 km s-1. A zero velocity layer is detected in every instantaneous model of the velocity stratification. The results suggest, that the zero velocity may occur in a considerable range of the optical depths from log depth -2 to log depth -3.5.