SIMBAD references

Orbits of close-in planets can shrink significantly due to dissipation of tidal energy in a host star. This process can result in star-planet coalescence within the Galactic lifetime. In some cases, such events can be accompanied by an optical or/and UV/X-ray transient. Potentially, these outbursts can be observed in near future with new facilities such as LSST from distances about few Mpc. We use a population synthesis model to study this process and derive the rate of star-planet mergers of different types. Mostly, planets are absorbed by red giants. However, these events, happening with the rate about 3 per year, mostly do not produce detectable transients. The rate of mergers with main sequence stars depends on the effectiveness of tidal dissipation; for reasonable values of stellar tidal quality factor, such events happen in a Milky Way-like galaxy approximately once in 70 yr or more rarely. This rate is dominated by planets with low masses. Such events do not produce bright transients having maximum luminosities <= 10^36.5 ^erg s^–1. Brighter events, related to massive planets, with maximum luminosity ∼10^37.5-10³⁸ erg s^–1, have the rate nearly five times smaller.