Astrophysicists Imaged 74 Exocomet Belts Orbiting Nearby Stars 

Eddie Gonzales Jr. – MessageToEagle.com – Astrophysicists, led by a Trinity team, have imaged numerous exocomet belts and their tiny pebbles around nearby stars for the first time.

All 74 exocomet belts, as imaged in this study. Image: Prof. Luca Matrà.

Crystal-clear images show light being emitted from millimetre-sized pebbles within the belts that orbit 74 nearby stars of a wide variety of ages – from those that are just emerging from birth to those in more mature systems like our own Solar System.

The REASONS (REsolved ALMA and SMA Observations of Nearby Stars) study marks such a significant milestone in the study of exocometary belts because its images and analyses reveal where the pebbles, and hence the exocomets, are located. They are typically tens to hundreds of au (the distance from Earth to the Sun) from their central star.

In these regions, extreme cold (-250 to -150°C) freezes most compounds, including water, into ice on exocomets. Astrophysicists study the locations of ice reservoirs in planetary systems. REASONS is the first program to reveal the structure of these belts across 74 exoplanetary systems.

The Atacama Large Millimeter/submillimeter Array (ALMA) in Chile and the Submillimeter Array (SMA) in Hawaii both observe electromagnetic radiation at millimeter and submillimeter wavelengths. This study used both arrays to produce images providing unprecedented information 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 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,” said Luca Matrà, Associate Professor in Trinity’s School of Physics, and senior author of the research article.

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.”

Some systems have multiple rings/disks, some of which are eccentric, which provides evidence that yet undetectable planets are present and their gravity affects the distribution of pebbles in these systems.

“The power of a large study like REASONS is in revealing population-wide properties and trends,” explained Prof. Matrà.

“For example, it confirmed that the number of pebbles decreases for older planetary systems as belts run out of larger exocomets smashing together, but showed for the first time that this decrease in pebbles is faster if the belt is closer to the central star. It also indirectly showed – through the belts’ vertical thickness – that unobservable objects as large as 140 km to Moon-size are likely present in these belts.

Dr David Wilner, Senior Astrophysicist at the Center for Astrophysics | Harvard & Smithsonian, underlined: “Arrays like the ALMA and SMA used in this work are extraordinary tools that are continuing to give us incredible new insights into the universe and its workings. The REASONS survey required a large community effort and has an incredible legacy value, with multiple potential pathways for future investigation.

“For example, the REASONS dataset of belt and planetary system properties will enable studies of the birth and evolution of these belts, as well as follow-up observations across the wavelength range, from JWST to the next generation of Extremely Large Telescopes and ALMA’s upcoming ARKS Large Program to zoom even further onto the details of these belts.”

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Written by Eddie Gonzales  Jr. – MessageToEagle.com Staff Writer