Astronomers in Santiago, Chile have made a groundbreaking discovery about a peculiar group of stars in the Orion constellation. Among them, FU Orionis, a double star system, has astounded experts since 1936 with its unexpected behavior. The central star of FU Orionis unpredictably brightened by 1,000 times, a phenomenon typically associated with dying stars, not young ones like FU Orionis. This unique trait gave rise to the classification of stars known as FUor stars, which periodically flare up in brightness before fading away over several years.
Thanks to innovative observations by the Atacama Large Millimeter/submillimeter Array (ALMA), astronomers have finally uncovered the mystery behind FU Orionis’ sudden luminosity increase. The findings, published in the Astrophysical Journal, reveal that these young outbursting stars rejuvenate their mass by absorbing energy from their surroundings through gravitational accretion. This process, responsible for shaping stars and planets, has puzzled scientists until now.
Using ALMA, researchers detected a stream of carbon monoxide descending onto FU Orionis, suggesting that the gas is a remnant from a prior, larger gas stream that once fueled the young stellar system. This interaction might have destabilized the system, triggering the surge in brightness. By analyzing various emissions and modeling mass flow, astronomers confirmed their findings, shedding light on stellar formation processes.
The ability of ALMA to explore a wide range of scales offers a comprehensive view of star and planet formation dynamics, from vast molecular clouds birthing hundreds of stars to smaller scales resembling solar systems. Sebastian Pérez of the Universidad de Santiago de Chile emphasizes the importance of understanding FUor stars in unraveling the mysteries of stellar and planetary genesis. The slow-moving carbon monoxide outflow observed around FU Orionis mirrors similar patterns seen around other protostellar entities, pointing to a commonality in star and planet formation.
This research not only deepens our knowledge of the origins of FU Orionis but also underscores the significance of outburst events in shaping the chemical composition of nascent stars’ accretion discs and the subsequent planets they host. Antonio Hales, leading the study, highlights the impact of these findings on our understanding of stellar and planetary formation, suggesting that all stars go through outburst events, influencing the composition of their surrounding planetary systems. After a decade of studying FU Orionis with ALMA, researchers are thrilled to have finally unraveled some of the star system’s long-held secrets.