Fomalhaut increasingly resembles the solar system as it was four billion years ago.
An international team of astronomers using the Chilean Atacama Large Millimeter / Submillimeter Array (ALMA) radio telescope captured the first complete image of the ring of dust and space debris surrounding the young star Fomalhaut. In the millimeter range, the belt of gas and stony material is very clearly visible. The 25 light-years separating it from us practically does not interfere with research.
Previous observations of the same star, made five years ago, when the radio telescope was still under construction, revealed about half of the ring's contents. This result was then taken as an omen of great opportunities for the future, and the assessment seems to have paid off.
ALMA radio telescope. Photo by NRAO
As seen in the image, a band of ice dust about 2 billion kilometers wide formed about 20 billion kilometers from the star. “ALMA provided us with a strikingly clear image of a fully formed disk of space debris,” said Meredith MacGregor, lead author of one of two papers accepted for publication in the Astrophysical Journal. "Finally, we saw a well-defined disc shape that can tell a lot about the planetary system located inside, responsible for its very peculiar appearance."
Using new ALMA data and detailed computer simulations, the researchers were able to calculate the exact location, width and geometry of the disc. These parameters confirm that such a narrow ring is probably created by the gravitational influence of the planets of the system.
Combined image of the Fomalhaut system. Radio telescope data (shown in orange) are superimposed on a photograph taken in the optical range. Photo by NRAO
A disk made from space debris is a fairly common occurrence in young stars. Astronomers associate its origin with ongoing collisions of planetesimals - growing embryos of planets within the system. The resulting debris from collisions absorbs light from the central star and re-radiates this energy in the form of a faint glow of millimeter waves, which can be studied with ALMA.
Presumably, the Fomalhaut system is now going through about the same period of intense meteorite-cometary bombardment that happened in the solar system about four billion years ago. This is a young system - it is about 300-400 million years old, and its total life span will probably be about a billion years.
Using the same ALMA dataset, but focusing on individual millimeter-wave signals, the researchers also found massive accumulations of carbon monoxide in the same location as the debris disk.
“These data allowed us to establish that the relative abundances of carbon monoxide and carbon dioxide around Fomalhaut are about the same as comets in our solar system,” says Luca Matrà ), lead author of the team's second article. "This chemical similarity indicates a similarity between the conditions for the formation of comets in the Fomalhaut system and the solar system."