  We aim to improve our picture of the low chromosphere in the quiet-Sun
internetwork by investigating the intensity, horizontal velocity, size and
lifetime variations of small bright points (BPs; diameter smaller than 0.3
arcsec) observed in the Ca II H 3968 {\AA} passband along with their magnetic
field parameters, derived from photospheric magnetograms. Several high-quality
time series of disc-centre, quiet-Sun observations from the Sunrise
balloon-borne solar telescope, with spatial resolution of around 100 km on the
solar surface, have been analysed to study the dynamics of BPs observed in the
Ca II H passband and their dependence on the photospheric vector magnetogram
signal. Parameters such as horizontal velocity, diameter, intensity and
lifetime histograms of the isolated internetwork and magnetic Ca II H BPs were
determined. Mean values were found to be 2.2 km/s, 0.2 arcsec (150 km), 1.48
average Ca II H quiet-Sun and 673 sec, respectively. Interestingly, the
brightness and the horizontal velocity of BPs are anti-correlated. Large
excursions (pulses) in horizontal velocity, up to 15 km/s, are present in the
trajectories of most BPs. These could excite kink waves travelling into the
chromosphere and possibly the corona, which we estimate to carry an energy flux
of 310 W/m^2, sufficient to heat the upper layers, although only marginally.
The stable observing conditions of Sunrise and our technique for identifying
and tracking BPs have allowed us to determine reliable parameters of these
features in the internetwork. Thus we find, e.g., that they are considerably
longer lived than previously thought. The large velocities are also reliable,
and may excite kink waves. Although these wave are (marginally) energetic
enough to heat the quiet corona, we expect a large additional contribution from
larger magnetic elements populating the network and partly also the
internetwork.
