Elena Pancino : StarDance: the non-canonical evolution of stars in clusters

Speaker : Dr. Elena Pancino (INAF - Osservatorio Astrofisico di Arcetri)
Date :12th November, 2024
Title : StarDance: the non-canonical evolution of stars in clusters
Abstract : Thanks to their ubiquity, brightness, and the fact that they are
made of stars with similar properties, star clusters have been
used as astrophysical laboratories or test particles in an
impressive range of research domains. However, we still do not
understand fundamental details of their formation and evolution.
In spite of recent technological progress, a list of unsolved
problems and apparently isolated mysteries has been accumulating
over time, some standing since decades. Among them, the existence
of multiple stellar populations in globular clusters, with
different chemistry, has challenged generations of researchers.
They are not the result of classical galactic chemical evolution,
mostly mediated by supernovae, and they jeopardize the use of
clusters as simple stellar population templates for extragalactic
studies. Given the mounting problems faced by the most favored
scenarios to explain multiple populations, it is now time to revisit
the foundations of our current thinking. New results show that:
(i) the peculiarities in the chemistry of multiple populations
are not limited to the oldest globular clusters;
(ii) they can be transient in the evolution of individual cluster
stars; and most importantly (iii) binary interactions and fast
stellar rotation cannot be neglected in the study of star clusters
and do have the capability to produce the observed chemistry.
The StarDance hypothesis assumes that multiple stellar populations
and five other non-canonical stellar populations (extreme
horizontal branch stars and hot sub-dwarfs;
extended main sequence turn-offs; red stragglers and sub-subgiants;
lithium-rich stars; and blue stragglers) are caused by the
interplay between stellar rotation and binary interactions,
that are greatly enhanced in the special environment of
star cluster, with spectacular results.