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The Reasons (REsolved ALMA and SMA Observations of Nearby Stars) survey analyzed 74 belts of planetesimals belonging to stars within 500 ly from the Sun and found an incredible variety of ages, shapes and sizes.
Source➡️ https://www.iac.es/en/outreach/news/astrophysicists-reveal-structure-74-exocomet-belts-orbiting-nearby-stars-landmark-survey
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The Reasons (REsolved ALMA and SMA Observations of Nearby Stars) survey analyzed 74 belts of planetesimals belonging to stars within 500 ly from the Sun and found an incredible variety of ages, shapes and sizes.
Source➡️ https://www.iac.es/en/outreach/news/astrophysicists-reveal-structure-74-exocomet-belts-orbiting-nearby-stars-landmark-survey
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Using the ALMA and SMA telescopes, researchers have for the first time observed in detail the light emitted by millimetre-sized pebbles within these belts, which are located at large distances from their stars (tens or hundreds of astronomical units).
The images show a variety of structures,
with some belts resembling narrow rings similar to the Edgeworth-Kuiper belt in our own solar system, while others are broader and more disk-like.
The belt regions are extremely cold, with temperatures ranging from -250 to -150 degrees Celsius, where water and other compounds are
frozen into ice.
Exocomets, which are blocks of rock and ice at least 1 km across, collide to produce the observed pebbles. This suggests such belts are common in planetary systems (present in at least 20% of them), providing clues to their formation and evolution.
The presence of rings or eccentric disks indicates that there may be undetected planets, whose gravity affects the distribution of pebbles.
The study showed that the number of pebbles decreases in older systems, but this decrease is faster if the belt is closer to the central star.
The research paves the way for future studies with programs such as ARKS (The ALMA survey to Resolve exoKuiper belt Substructures) and observations with the James Webb Space Telescope, which could further clarify the formation of planetary systems.
This study represents a significant advance in the understanding of exocomet belts and the dynamics of planetary systems, suggesting that the processes observed in our solar system may be common in the universe.
Credits: L. Matrà et al., A&A, 693, 2025
Paper: https://www.aanda.org/articles/aa/full_html/2025/01/aa51397-24/aa51397-24.html