PREDNASAJUCI / LECTURER :

Ján Budaj

(1) Astronomical Institute, Slovak Academy of Sciences,
059 60 Tatranská Lomnica

NAZOV / TITLE :

WeSb~1: planetary nebula whose central star is orbited by a swarm of dusty objects

ABSTRAKT / ABSTRACT :

Exoplanets and smaller bodies have been detected orbiting red giant stars as well as
around white dwarfs (WDs). However, we do not know of any such objects in planetary
nebulae (PNe), the short-lived stage of stellar evolution between the asymptotic giant
branch (AGB) and WD phases. How planets, asteroids, and comets evolve through their
host star's PN phase remains a mystery.

The destruction of an old planet or the formation of a new one may be accompanied
by dust clouds, streams, eddies, or clumpy structures that might eclipse its host star.
We have searched for indications of eclipsing dust clouds in PNe using archival
photometric data from Gaia, ZTF, and other projects.

We found one object that features numerous dimming events with a typical durations
of a few days to weeks and depths of about 1 magnitude. The variability culminated
in July-October 2021 with a couple of eclipses that were 3 magnitude deep. This
variability is mainly stochastic with an indication of a 400 d period. The occultations
are almost grey indicating dust grains larger than about 0.1 micron. Based on our
follow-up observations (imaging, spectroscopy, and photometry), we argue that these
events are most likely caused by debris from a disintegrated small rocky body orbiting
the star or by a predecessor of debris discs seen around some polluted WDs.