Scientific Rationale
Massive stars are the driving engines of the Universe – in energy, momentum, and baryonic cycling through galaxies across cosmic time. Without them, the present Universe would not exist in its observed form.
Born with more than eight times the mass of our Sun, massive stars are the most powerful nuclear reactors in nature, capable of fusing progressively heavier elements until their final collapse and potential explosion as core-collapse supernovae. Throughout their evolution, they bridge key frontiers of modern astrophysics, linking processes that span from star formation within molecular clouds to the chemical and dynamical evolution of entire galaxies.
Massive stars act as the most active agents in galactic ecosystems
Their intense UV radiation and powerful stellar winds inject vast amounts of energy and momentum into the surrounding interstellar medium. During their lifetimes – from the early stages as hot, luminous blue stars to their more advanced evolutionary phases as red supergiants or Wolf–Rayet stars – they continuously shape their environment through photoionization, mechanical feedback, and chemical enrichment.
When they end their lives as core-collapse supernovae (CCSNe), these stars release the heavy elements synthesized in their interiors, enriching their host galaxies with key ingredients for planetary formation and life itself, such as oxygen, carbon, and phosphorus. These cataclysmic explosions may also trigger new episodes of star formation, while in other cases, they can sterilize planetary systems orbiting nearby solar-type stars through intense radiation and shock waves.
The paramount role of massive stars as cosmic engines began with the very first generation of stars in the early Universe
Simulations suggest that these primordial stars were extremely massive – tens to hundreds of solar masses – and contributed significantly to the reionization of the Universe. Since then, multiple generations of massive stars have populated every star-forming galaxy, becoming essential to our understanding of galactic evolution and a variety of astrophysical phenomena.
Massive stars have also been described as gifts of nature
Their extreme luminosities make them observable as resolved stellar populations in nearby galaxies, even several megaparsecs away, with current observational facilities. As individual objects, they are exquisite probes of present-day chemical abundances in the galaxies they inhabit. Their spectra complement – and often improve upon – the information derived from the analysis of emission-line spectra of associated H II regions, providing an independent, robust approach to measuring metallicities and abundance patterns in star-forming galaxies.
Also, their stellar corpses – neutron stars (NSs) and black holes (BHs) – provide unique laboratories for testing extreme physics. These compact objects allow us to probe the behavior of degenerate matter, strong-field gravity, and relativistic magnetospheres. Some NSs act as precise cosmic clocks in pulsar timing arrays, while the mergers of binary compact objects emit gravitational waves (GWs) detectable by current instrumentation from the ongoing LIGO-Virgo-KAGRA collaboration, opening a completely new window to the Universe. These GW events connect directly to the final evolutionary stages of massive binaries, linking stellar and binary astrophysics to multi-messenger astronomy.
Understanding massive star physics and evolution is of utmost importance for understanding the Universe across cosmic time
Because of their profound influence, accurate prescriptions for the physical properties and evolution of massive stars (both as individual objects and stellar populations) are essential ingredients in models of galactic evolution across cosmic history. Their spectra underpin the interpretation of star-forming regions observed at all redshifts.
Therefore, achieving a comprehensive understanding of the physical processes governing massive-star evolution – under different environmental and metallicity conditions – is of utmost importance. This understanding must incorporate not only the complex physics of single-star evolution, including rotation, stellar winds, and internal transport of chemical elements and angular momentum, but also the equally crucial impact of binary interactions. Observations have revealed that a large fraction – likely the majority – of massive stars are born in binary or higher-order multiple systems, and their interactions through mass transfer, mergers, or common-envelope evolution profoundly shape their subsequent fate.
Developing such a holistic understanding of massive-star physics requires not only theoretical insights but also the ability to gather and interpret high-quality observational data.
This Winter School aims to integrate different state-of-the-art observational, theoretical and computational techniques used in massive star research to aid the new generation of stellar astrophysicist to step forward in our understanding of the important role of massive stars in astrophysics.
For the new generation of stellar astrophysicists, it is crucial to acquire a solid grounding in the observational, analytical, and modeling tools that enable the empirical characterization of massive stars and their environments. Progress in the field depends on the combination of three key pillars:
- high-quality observations across multiple wavelengths,
- sophisticated modeling of their stellar interiors and evolution, as well as their stellar atmospheres and emergent spectra, and
- advanced techniques for quantitative spectroscopic analysis (QSA), both for single and binary systems.
Participants will learn how these objects connect stellar, galactic, and cosmological processes, serving as natural laboratories for physics under extreme conditions and as luminous beacons for probing the distant Universe. By combining theoretical lectures with practical sessions focused on data analysis and modeling, the school will train a new generation of researchers capable of using massive stars as powerful tools to decipher the Universe – from their turbulent births to their spectacular deaths as CCSNe and GW sources.
