In a groundbreaking achievement, astrophysicists led by a team from Trinity College Dublin have, for the first time, captured crystal-clear images of numerous exocomet belts orbiting nearby stars. These images reveal the millimeter-sized pebbles within the belts, providing unprecedented insight into the composition and distribution of exocomets around 74 nearby stars of varying ages.
The study, known as REASONS (REsolved ALMA and SMA Observations of Nearby Stars), marks a significant milestone in studying exocometary belts. The images reveal the precise locations of the pebbles and exocomets, typically tens to hundreds of astronomical units (AU) from their central stars.
In these frigid regions, temperatures range from -250 to -150 degrees Celsius, causing most compounds, including water, to freeze as ice on the exocomets. This discovery highlights the ice reservoirs of planetary systems, unveiling the structure of these belts for a large sample of 74 exoplanetary systems.
The study utilized the Atacama Large Millimeter/Submillimeter Array (ALMA) in Chile and the Submillimeter Array (SMA) in Hawaii, providing detailed images and valuable data on exocomets.
“Exocomets are boulders of rock and ice, at least 1 km in size, which smash together within these belts to produce the pebbles observed with the ALMA and SMA arrays of telescopes. Exocometary belts are found in at least 20% of planetary systems, including our own Solar System,” explained Luca Matrà, Associate Professor at Trinity’s School of Physics and senior author of the research article published in Astronomy and Astrophysics.
The images reveal remarkable diversity in the structure of belts. Some form narrow rings like our Solar System’s Edgeworth-Kuiper belt, while others are wide and disk-like. Some systems contain multiple rings or disks with eccentric shapes that suggest the presence of yet undetectable planets influencing the distribution of pebbles.
Prof. Matrà highlighted the study’s significance: “The power of a large study like REASONS is in revealing population-wide properties and trends. For example, it confirmed that the number of pebbles decreases for older planetary systems as belts run out of larger exocomets smashing together, but it showed for the first time that this decrease in pebbles is faster if the belt is closer to the central star.”
Dr David Wilner, Senior Astrophysicist at the Center for Astrophysics | Harvard & Smithsonian, emphasized the extraordinary capabilities of the ALMA and SMA arrays, noting, “The REASONS survey required a large community effort and has an incredible legacy value, with multiple potential pathways for future investigation.”
The REASONS dataset will enable further studies on the birth and evolution of these belts and follow-up observations across the wavelength range, paving the way for future research with tools like the JWST, Extremely Large Telescopes, and ALMA’s upcoming ARKS Large Program.
Journal Reference:
- L. Matra, S. Marino et al. REsolved ALMA and SMA Observations of Nearby Stars (REASONS): A population of 74 resolved planetesimal belts at millimeter wavelengths. Astronomy and Astrophysics. DOI: 10.1051/0004-6361/202451397
Source: Tech Explorist
