Astrophysicists from Trinity College Dublin have successfully imaged a significant number of exocomet belts surrounding nearby stars, providing insights into the location of ice reservoirs in planetary systems.
The project, named REASONS (REsolved ALMA and SMA Observations of Nearby Stars), utilized advanced imaging techniques to capture millimeter-sized pebbles emitting light from within these belts. These belts are typically located tens to hundreds of astronomical units (AU) away from their central stars.
The research team analyzed 74 exoplanetary systems, marking the largest sampling of exocometary belts to date. Temperatures in these regions range from -250 to -150 degrees Celsius, causing most compounds, including water, to freeze.
Using the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile and the Submillimeter Array (SMA) in Hawaii, the study has revealed unprecedented information about exocomet populations. According to Luca Matrà, an associate professor at TCD and senior author of the study published on January 17 in Astronomy and Astrophysics, “Exocomets are boulders of rock and ice, at least 1 km in size, which collide within these belts to produce the pebbles we observe.”
The study also confirmed that the number of pebbles decreases in older planetary systems as larger exocomets collide, with a faster decline noted for belts closer to their central star. Dr. David Wilner, a senior astrophysicist at the Centre for Astrophysics, remarked that the dataset will enhance future studies on the birth and evolution of these belts.
Additionally, the study indicates a diversity in belt structures, with some appearing as narrow rings while others are wider, resembling disks. This diversity suggests a complex interaction of gravitational influences in these systems. The REASONS project was supported by various organizations, including Taighde Éireann - Research Ireland and the EU Horizon 2020 research program.