Type II Supernovae: The Chaotic Deaths of Supergiants and their Cosmic Implications

October 2026

San Pedro de Atacama, Chile TBC

Type II supernovae (SNeII) are among the brightest and most common stellar explosions in the Universe, signaling the dramatic final chapters in the lives of many massive stars. These events originate from massive stars—those with initial masses exceeding eight times that of the Sun—that have retained most of their hydrogen-rich envelopes. As these stars reach the end of their life cycles, their iron cores collapse, unleashing a burst of neutrinos and a shock wave that powers the ensuing explosion and its striking luminosity.

While much is understood about the underlying mechanisms that shape SNII spectra and light curves—namely the luminosity post-maximum from an ionised hydrogen recombination front followed by energy input from radioactive cobalt decay in the tail—many critical questions remain. The full story of their progenitor systems is still unfolding. What is the precise initial mass range for these stars? How do binarity, rotation, internal mixing, and metallicity affect the observable diversity of these explosions? And, fundamentally, what exact process revives the shock wave to initiate the explosion?

This workshop will create a dedicated space to confront such questions through both observational and theoretical perspectives. We aim to explore the connections between pre-supernova stellar structure, explosion dynamics, and observable features. The most up-to-date findings using hydrodynamical simulations, radiative transfer modeling, archival or new multi-wavelength observations, light curve and spectral modeling, and machine-learning-based classifications in time-domain surveys will all be welcome contributions. Furthermore, we will target contributions that link SNeII to broader astrophysical contexts, such as dust production, galactic feedback, chemical enrichment, and their utility as cosmological distance indicators.

Adding to the intrigue of the SNII phenomenon, recent observations reveal that a significant fraction of SNeII exhibit clear signs of interaction between the supernova ejecta and circumstellar material. This suggests that extended stellar atmospheres or mass-loss episodes in the final years before explosion may play a more central role than previously thought. Understanding the physical mechanism that produces this circumstellar material requires the combined expertise of scientists working on supergiant mass loss and those working on early-time SNII observations. This conference will provide the platform for such collaborative discussion.

Despite their significance in many areas of astrophysics and cosmology, dedicated scientific attention to SNeII has been surprisingly sparse. Conferences rarely give them more than a brief spotlight, and they are often overshadowed by the broader diversity of (much rarer) transient phenomena. The upcoming flood of data from facilities such as LSST, 4MOST, and JWST underscores the urgency of refining our physical models and classification schemes for these most common transients. We believe the time is ripe for a focused international conference devoted exclusively to SNeII—one that bridges the gap between massive star evolution and core-collapse physics, while exploring their use as cosmological tools. Such a gathering will bring together experts in both massive stellar evolution and SNeII from across the globe to tackle the pressing questions still surrounding these events, to re-center them as a cornerstone of modern astrophysics and cosmology, and leverage their potential in upcoming survey-era discoveries.

More information will be published in the coming weeks/months!

E-mail: SNII-RSG-2026@eso.org

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