spaceSpace and Physics

Incredible Ice Ring Spotted In Young Planetary System


Dr. Alfredo Carpineti

Senior Staff Writer & Space Correspondent

clockMay 19 2017, 16:45 UTC

Composite image showing the visible debris disk in blue and the ice ring in yellow. ALMA (ESO/NAOJ/NRAO), M. MacGregor; NASA/ESA Hubble, P. Kalas; B. Saxton (NRAO/AUI/NSF)

An international team of astronomers have snapped a gorgeous view of an icy ring of debris in a young and nearby star system. The spectacular structure is the likely result of exocomet collisions, 2 billion kilometers (1.2 billion miles) wide and 20 billion kilometers (12.4 billion miles) from its star Fomalhaut.

The discovery, published in two papers in the Astrophysical Journal, was only possible thanks to the Atacama Large Millimeter/submillimeter Array (ALMA). Fomalhaut is the brightest star in the constellation Piscis.


“ALMA has given us this staggeringly clear image of a fully formed debris disk,” Meredith MacGregor, one of the lead authors from the Harvard-Smithsonian Center for Astrophysics in Cambridge, said in a statement. “We can finally see the well-defined shape of the disk, which may tell us a great deal about the underlying planetary system responsible for its highly distinctive appearance.”

Fomalhaut is located 25 light-years away and it’s an incredibly young system, estimated to have formed 440 million years ago. It is also one of the first targets that ALMA looked at in 2012 while still under construction. While the observations showed part of the ring and the intriguing debris disk, only now have astronomers been able to fully outline the properties of the system.

By constructing a computer model based on the data, astronomers were able to show that the disk might be influenced by planets within the system. There’s at least one planet orbiting Fomalhaut and more might be beyond our detection limit. ALMA’s observations will help astronomers understand what these planets might be made of.


“These data allowed us to determine that the relative abundance of carbon monoxide plus carbon dioxide around Fomalhaut is about the same as found in comets in our own solar system,” said Luca Matrà of the University of Cambridge, UK, and lead author on the team’s second paper. “This chemical kinship may indicate a similarity in comet formation conditions between the outer reaches of this planetary system and our own.”

By observing in exquisite detail younger and younger stellar systems, ALMA is pushing the envelope on what we can detect.

“Twenty years ago, the best millimeter-wavelength telescopes gave the first fuzzy maps of sand grains orbiting Fomalhaut. Now with ALMA’s full capabilities the entire ring of material has been imaged,” Fomalhaut Principal investigator Paul Kalas, from the University of California at Berkeley, added. “One day we hope to detect the planets that influence the orbits of these grains.”

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