ИСТИНА

Recent studies (e.g. [1]) demonstrate that planet-star coalescences due to tidal effects can result in flare events observable in optical, UV and soft X-ray bands. Energy release can be as high as $10^{37}-10^{38}$ erg~s$^{-1}$ in optics, and up to $10^{36}$ erg~s$^{-1}$ -- in EUV/X-ray. This is compatible with nova flares. In our study we use population synthesis approach to estimate the rate of planet-star coalescences in a Milky way-like galaxy. We use mass and initial semimajor axis distributions based on population modeling [2], [3]. We derive type and luminosity distributions of events depending on star and planet parameters. We obtain that in a Milky way-like galaxy frequency of optical transients is $\sim 2.2\cdot 10^{-2}$~yr$^{-1}$, and EUV/X-ray transients -- $\sim 2\cdot 10^{-3}$~yr$^{-1}$. Based on these results we discuss perspectives to detect such events with future instruments.