Astrophysicists, led by Trinity College Dublin and including scientists from University of Exeter, Harvard University, University of Jena and UK ATC, have made a significant breakthrough by imaging 74 exocomet belts around nearby stars.
This achievement, which comes from the REASONS (REsolved ALMA and SMA Observations of Nearby Stars) study, marks the first time such a large number of exocomet belts have been observed in detail. The study utilized the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile and the Submillimeter Array (SMA) in Hawaii to capture crystal-clear images of millimetre-sized pebbles within these belts.
These belts are typically tens to hundreds of au (astronomical units, ie the distance from Earth to the Sun) from their central star. In these regions, it is so cold (-150 to -250 degrees Celsius) that most compounds, including water, are frozen as ice on these exocomets. What the astrophysicists are therefore observing is where the ice reservoirs of planetary systems are located.
Luca Matrà, Associate Professor in Trinity's School of Physics and lead author on this new paper in Astronomy & Astrophysics, said “Exocomets are boulders of rock and ice, at least 1km in size, which smash together within these belts to produce the pebbles that we observe here with the ALMA and SMA arrays of telescopes. Exocometary belts are found in at least 20% of planetary systems, including our own Solar System."
Dr Sebastián Marino, Royal Society University Research Fellow at the University of Exeter, and coauthor in this study, added: “The images reveal a remarkable diversity in the structure of belts. Some are narrow rings, as in the canonical picture of a 'belt' like our Solar System's Edgeworth-Kuiper belt. But a larger number of them are wide, and probably better described as 'disks' rather than rings."
Dr Mark Booth, Project Scientist at UK ATC and coauthor on this study, said: “By observing the shape of these exocomet belts, we can look for indications of planets in the system that we hope to detect with other telescopes like JWST and the upcoming ELT. Those telescopes also allow us to see the dust produced by the exocomets. Comparing the distributions of dust seen by JWST and pebbles seen by ALMA allows us to learn about the physical processes in these planetary systems and how they compare to our own Solar System."
Read the Astronomy & Astrophysics paper.
