SIGNATURES OF EXOCOMET ACTIVITY AROUND STARS AT DIFFERENT EVOLUTIONARY STAGES

Анотація

We discuss the current state of
problems associated with the discovery and study of
exocomets, i.e objects of extrasolar systems, that are in
many aspects similar to the solar system comets. Thus
far, more than 4,300 exoplanetary systems have been
discovered, but little is known about the populations
of subplanetary bodies in these systems, in particular
comets. Existing theories of planet formation suggest
that populations of small bodies in the planetary
systems should be numerous, especially at the early
stages of their formation. Currently, most of the
stars observed with the confirmed transit exoplanets
and candidate stars with exoplanetary systems have
been collected in the Kepler and TESS space mi-
ssion databases. These databases can be used for a
search and study of the exocomet transit signatures
in extrasolar systems. So far, the number of observed
cases of exocomet transits has been small, only about
20 events. Due to the rapid accumulation of data, new
researches aimed to identify the specific transit events
and study the physical characteristics of small bodies in
the extrasolar systems are of great importance.Worth
considering is the concept of “falling evaporating
bodies”, massive enough bodies surrounded by mini-
atmospheres, which fall on the parent star. The events
might produce the variable, short-time red-shifts of
some spectral features in their spectra. Alternative
evidence of exocomet transits can be obtained by
detection of the cometary emissions in CO, C, and
O lines in the millimeter region of the spectra of
debris disks by the ALMA and APEX telescopes.
We discuss the known detection methods based on
the analysis of the photometric and spectral series
of observational data of space missions and ground-
based complexes. Some results of experimental studi-
es of the exocometary transit signatures obtained by
other authors are presented and discussed.