Fomalhaut is the brightest star in the constellation Piscis Austrinus. It’s a white star with a mass a little more than twice the Sun 25 light years away. The observations suggest that Fomalhaut is between 100 and 300 million years old. Although young in astronomical terms, its mass is such that it’s estimated that it can live for a billion years or so, a life that will be about one-tenth the length of the Sun’s.

In the ’80s, the satellite IRAS (InfraRed Astronomical Satellite) found an excess of infrared light at the location of Fomalhaut and astronomers interpreted it as a ring of debris around the star. Several years later, the Hubble Space Telescope allowed scientists to obtain visible light images of the ring and estimate that the average distance of the material from Fomalhaut is superior to 17 billion kilometers (more than 10 billion miles), or ten times higher than Neptune’s distance from the Sun.

In 2005 it was hypothesized that near the inner edge of the ring of debris there was a planet. In 2008, a composite image made by putting together various photographs taken with the ACS (Advanced Camera for Surveys) of the Hubble Space Telescope made astronomers think they had discovered for the first time a planet in another star system in a direct way, thanks to the visible light emitted by it.

A study published earlier this year however raised doubts on the existence of this planet, in the meantime called Fomalhaut b. New observations with the Spitzer Space Telescope could suggest that a cloud of dust was mistaken for a Jupiter-sized planet surrounded by rings much larger than those of Saturn.

Now further research has allowed scientists to collect new information on Fomalhaut, the dust ring that surrounds it and possible planets that exist in that area.

The Herschel Space Telescope allowed scientists to observe the ring around Fomalhaut in different bands of electromagnetic frequencies to get more information on the characteristics of the dust it contains.

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According to those observations, the ring is composed of tiny grains of dust but that’s in contrast with previous observations, which suggested that it was composed of much larger grains. This contradiction can be resolved if the ring is made up of fluffy aggregates that are relatively large but composed of smaller grains with a lot of empty space within their structure.

In our solar system, such aggregates are formed by the collision of comets therefore it’s possible that the ring around Fomalhaut was formed the same way.

The stellar wind of Fomalhaut should slowly wipe away the dust so if the ring still exists there should be continuous collisions between comets which add new dust maintaining the ring.

The ALMA (Atacama Large Millimeter / submillimeter Array) is an astronomical radiointerferometro still under construction at 5,000 meters (a little more than 3 miles) of altitude in the Atacama Desert in Chile. It’s already partially operational and the observations of the Fomalhaut system suggest that close to its large dust ring there are two planets, one near its inner edge and one near its outer edge.

Combining the observations made with the ALMA with computer models that simulate the possible orbits of the planets and their gravitational effects on the dust ring, the scientists infer that their masses are less than previously thought. In fact, according to the simulations, high-mass planets would destroy the ring so the two planets discovered may be larger than Mars but not more than a few times the Earth.

Obviously, in the future new observations of the Fomalhaut system will be made and at the end of this year the ALMA should be completed. Scientist will obtain better information on this system, which is very interesting because it’s still being formed and because its planets, if their existance will be confirmed, are abnormally far from their star.