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A newborn exoplanet is apparently moving.
Astronomers have spotted complex ring structures in the outer part of the disk of dust and gas which surrounds the young star HD 169142, located about 370 light-years from Earth in the constellation Sagittarius.
The researchers report in a new study that these rings were probably carved by a migrating baby planet about 10 times more massive than the Earth.
Related: Gallery: The Strange Foreign Planets
Comparison between an ALMA image and a theoretical simulation of the protoplanetary disk in HD 169142. The simulated image incorporates a planet 10 times the mass of the Earth, sculpting the outer regions of a protoplanetary disk. Fine rings are composed of dust particles that are trapped in concentric structures by excited pressure waves during the interaction between the planet and the disc.
(Image: © N. Lira – ALMA (ESO / NAOJ / NRAO), S. Perez – USACH / UChile)
A tagged ALMA image describing the structure of the protoplanetary disk in the system of the young star HD 169142.
(Image: © N. Lira – ALMA (ESO / NAOJ / NRAO), S. Perez – USACH / UChile)
Scientists studied HD 169142 using the radio-telescope network in northern Chile, the Atacama Large Millimeter / Subillimeter Array (ALMA). ALMA has observed many newborn star systems in recent years, find gaps and rings in the protoplanetary disks of almost all. Most astronomers believe that such structures are cut by the fusion of planets.
So it's not a shock if ALMA spotted holes in the disc around HD 169142, a star about 1.7 times more massive than our sun. But the details were surprising. In addition to a large internal space probably associated with one or more giant protoplanets, the disc of HD 169142 has thin rings and spaces in its outer part, a region in which broad and smooth rings tend to predominate, explained the researchers.
The team performed computer simulations to understand the possible origin of the structures. This work identified the culprit as being a mini-Neptune who formed about 69 astronomical units (AU) from the parent star, then moved inward to about 64 AU. (An AU is the average Sun-Earth distance – about 93 million kilometers, or 150 million kilometers.)
"Global migration naturally explains the distinct mutual separations between narrow rings," the researchers wrote in a new article, published online today (June 14) in The astronomical journal.
"Here, a small planet that interacts with tiny dust particles can reproduce these rings in isolation, revealing its properties in an indirect way," said lead author Sebastian Pérez of the University of Santiago in Chile. added in a statement. "The community has made great progress in interpreting these sharp rings seen in the younger planetary systems.This experiment and other similar experiments open up new possibilities for characterizing extrasolar super-planets."
Mike Wall's book on the search for extraterrestrial life, "Over there"(Grand Central Publishing, 2018, illustrated by Karl Tate), is out now. Follow him on Twitter @michaeldwall. Follow us on twitter @Spacedotcom or Facebook.
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