Outbursts of comets at large heliocentric distances: Concise review and numerical simulations of brightness jumps

The outburst of comet brightness is spectacular and well-known manifestation of the physical activity of these relatively small cosmic bodies. The outbursts of brightness are observed for periodic comets, as well as for the comets moving along parabolic trajectories. The most known comet representing such kind of activity is the comet 29P/Schwassmann-Wachmann. There is a number of hypotheses put forward so far in scientific literature, many of them are trying to establish ultimate cause of the phenomenon. However, careful analysis leads to the conclusion that there may be several different causes of cometary outbursts or even combination of them, which in favourable conditions may initiate the outbursts of brightness. The main goal of the work is not the searching for the new mechanisms of brightness outbursts, but rather, based on existing models to make new and more accurate calculations of the comet's brightness jumps during their outbursts at large heliocentric distances. Numerical simulations of changes of brightness for three hypothetical comets orbiting in the solar system were carried out. The obtained results are consistent with observations of real comet outbursts.