Chasing Stellar Outbursts: Planet Formation Phenomena Discussed in Budapest

Stars, including our own Sun, form from dense clouds of gas and dust. However, their formation is not a smooth, predictable evolutionary process; it can include highly turbulent episodes. Detailed studies of these events and an understanding of their underlying physical mechanisms have been an important research topic at the Astronomical Institute for many years, supported by the European Research Council (ERC) between 2017 and 2023.

When a young star undergoes such a turbulent phase, material from the circumstellar disk can accrete onto the protostar at rates up to a hundred times higher than normal. The energy released by this enhanced accretion causes the system to brighten dramatically, resulting in an outburst. Conference participants reviewed newly discovered outbursts from recent years, many of which have been monitored with important contributions from the Piszkéstető Observatory. Researchers specialising in theoretical and numerical modelling also presented the physical mechanisms that may drive these phenomena.

One of the most exciting questions in this field is how such outbursts alter the circumstellar disk – the environment from which planets later form. The increased heating can trigger structural, chemical and mineralogical changes in the disk material, potentially influencing the conditions under which planets emerge. These processes may contribute to the remarkable diversity observed among exoplanets.

Researchers at the HUN-REN CSFK Astronomical Institute play a leading role internationally in this field. Dr Zsófia Nagy leads the international GLORIOUS collaboration, which specialises in monitoring newly discovered outbursts, while Dr Ágnes Kóspál and her research group investigate the physics of eruptive events and their effects on circumstellar disks through detailed studies of well-known prototype objects.

The conference brought together 40 researchers in person and a further 40 online, representing 48 research institutes and universities across 20 countries. Participants agreed that forthcoming sky surveys and observational facilities, including future Gaia data releases and observations from the Vera C. Rubin Observatory, will open up exciting new opportunities. These may help answer one of the field’s most fundamental questions: do all young stars experience turbulent eruptive phases, or are such events signatures of a particular evolutionary pathway?