OSIRIS · Observational Signatures of planet formation in externally IRradiated dIScs

Observational Signatures of planet formation in externally IRradiated dIScs

Most stars—and most planets—form in massive, crowded stellar nurseries. Although planet formation is often assumed to be an isolated process, the reality is far more complex. Star forming regions are often flooded by intense ultraviolet (UV) radiation from nearby massive stars, which drives photoevaporative winds that strip away disc material, potentially halting planet formation before it even begins. These regions are dynamic environments where stars move rapidly and pass close to one another, potentially perturbing the protoplanetary discs of gas and dust from which planets form. Close stellar encounters can truncate discs, stir their contents, or even eject material entirely, altering the conditions under which planets can grow. Compounding this complexity, significant reservoirs of dense gas and dust often remain in the vicinity of young stars. This material can obscure observations and shape the local radiation field, but may also accrete onto discs and stars, replenishing them with new material and extending their lifetimes. Despite these factors, protoplanetary are often interpreted as isolated objects. This understanding biases our interpretation of observational evidence. The OSIRIS project set to address this issue by uncovering how environmental factors affect the evolution of protoplanetary discs and the observational constraints on their properties. By linking new models with state-of-the-art data from cutting edge instruments such as the Atacama Large Millimeter/submillimeter Array (ALMA), OSIRIS connected theory with observation to answer a fundamental question: how does the birthplace of a planetary system affect the protoplanetary discs of dust and gas that we observe? To address this question, the project pursued thel key objectives: -- Develop and apply models that capture how the environment shapes the structure and evolution of protoplanetary discs in dynamically evolving star forming regions; -- Analyse and interpret the dynamical response of a disc to its external environment; -- Link theoretical predictions with observational diagnostics, enabling robust interpretation of environmental effects. The results of OSIRIS contribute to our understanding of the diversity of planetary systems observed today, offering a more complete picture of how and where planets can form. These insights help contextualise the formation of our own Solar System and guide the interpretation of exoplanet demographics. By integrating theoretical and observational approaches, OSIRIS enhances the scientific return of current and future astronomical facilities and strengthens Europe’s leadership in the study of planet formation under realistic, environmentally complex conditions.

Data: CORDIS, © European Union