Title: Understanding the Complexity of Long-Period Variables
Speaker: Michele Trabucchi
Affiliation: University of Padova
Room: Å101132
Time: 14:00-15:00
Abstract:
Long-Period Variable stars (LPVs) have been studied by western astronomers for over four centuries, at least since the first documented report of the brightness changes of Mira, the prototype of the homonymous sub-type of LPVs. Nowadays, we understand them to be stars born with about 1-10 times the solar mass at birth, currently experiencing the terminal stages of their evolution, namely the Asymptotic Giant Branch (AGB). Intrinsically very bright, these fascinating objects contribute substantially to the integrated luminosity and the spectral energy distribution of unresolved stellar populations, especially at infrared wavelengths, and play a crucial role in the enrichment of the interstellar medium in dust and nucleosynthesis products. Moreover, they follow period-luminosity and period-age relations with promising applications as standard candles and age tracers, especially in the modern era of large-scale time-domain surveys such as Gaia and the Rubin Observatory’s LSST. Yet, a comprehensive understanding of their behavior remains elusive, primarily because it emerges from a combination of strongly intertwined physical processes (convection, pulsation, dust formation, stellar winds, binary interactions), such that the standard assumptions made in stellar modeling often break down. This seminar is intended to convey a general overview of the properties of LPVs in order to appreciate their complexity, in light of the most recent results and in view of future challenges.