REASONS produced images that have provided more information on exocomet populations than ever before.
Astrophysicists led by a team from Trinity College Dublin (TCD) have imaged a large number of exocomet belts around nearby stars, observing where ice reservoirs of planetary systems are located.
Crystal-clear images from the team’s project titled REASONS (REsolved ALMA and SMA Observations of Nearby Stars), show millimetre-sized pebbles from within the belts emitting light, revealing to scientists the location of exocometary belts which are typically tens of hundreds of au (the distance from Earth to the sun) from their central star.
The team sampled 74 exoplanetary systems. In these regions, temperatures range from minus 250 to minus 150 degrees Celsius, freezing most compounds, including water.
Using the Atacama Large Millimetre/submillimetre Array (ALMA), an array of 66 radio telescopes in the Atacama Desert of northern Chile, and the Submillimetre Array (SMA), a similar eight-element array in Hawaii – both of which observe electromagnetic radiation at millimetre and submillimetre wavelengths – the study captured images that have provided researchers with more information on populations of exocomets than ever before, the team 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 20pc of planetary systems, including our own solar system,” said Luca Matrà, an associate professor in the TCD School of Physics and a senior author of the study that was published today (17 January) in the Astronomy and Astrophysics journal.
While Dr Sebastián Marino, a Royal Society University research fellow at the University of Exeter and a co-author of 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.”
Moreover, the study confirmed that the number of pebbles decreases for older planetary systems as the belts run out of larger exocomets smashing together, but also showed for the first time that this decrease in pebbles is faster if the belt is closer to the central star.
Dr David Wilner, a senior astrophysicist at the Center for Astrophysics Harvard and Smithsonian said: “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.”
The REASONS study was supported by funding from a number of organisations including Research Ireland, the EU Horizon 2020 research and innovation programme under a Marie Sklodowska-Curie grant and the Smithsonian Institution.
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