An article published in the magazine “Astrophysical Journal Letters” describes the discovery of a cold dust ring around Proxima Centauri, the star closest to the solar system. A team of researchers led by Guillem Anglada from the Instituto de Astrofísica de Andalucía (CSIC), Granada, Spain, used the ALMA radio telescope to locate that ring that extends for a distance between one and four times that of the Earth from the Sun. There might also be a second ring, much farther from its star, a situation that makes the researchers think of a complex solar system.
Proxima Centauri is in our neighborhood in astronomical terms, about 4.3 light years away from Earth and very close to the Alfa Centauri star pair. In August 2016, the discovery of Proxima b, an exoplanet slightly larger than Earth that orbits in the habitable area of Proxima Centauri, was announced. That discovery stimulated further research in the hope of finding other planets but the use of the ALMA radio telescope, inaugurated in March 2013, made it possible to discover at least one ring of dust.
The comparison is with some formations of the solar system such as the asteroid belt, the Kuiper belt and the dust that generates the so-called zodiacal light, but the belt around Proxima Centauri appears to be mainly formed of dust for a total mass estimated at a hundredth of the Earth’s. Its temperature is estimated at -230° Celsius and from this point of view it’s similar to the solar system’s Kuiper belt since it’s heated by a red dwarf much smaller than the Sun and also much colder.
Guillem Anglada emphasized the importance of this discovery that, after that of the planet Proxima b, indicates that there’s a complex system, not a single planet, around the star closest to the Sun. That’s because the dust belts are the remains of materials that failed to form a planet and were destroyed in collisions that produced second-generation dust. First generation dust is that from the original disk solar systems are formed from.
Studying one or more belts around another star can provide important clues to the evolution of that solar system. The presence of Jupiter and Saturn creates an instability in our solar system, making it impossible to form a planet between Mars and Jupiter but also generating a gravitational influence that had an effect on the evolution of objects in the Kuiper belt and the formation of dust in that area.
The data collected suggest that there may also be a second belt of dust around Proxima Centauri at a distance from the star about ten times higher than the first one. At that distance from the small and cold red dwarf, the temperatures are even lower so the emissions are really weak, making it difficult to establish its existence even with a powerful and sensitive instrument such as the ALMA radio telescope.
If the existence of the second dust belt was confirmed, this would indicate that the Proxima Centauri system has a rich history of interactions that led to the creation of the two belts. Further observations could not only provide more data to understand how many belts there are but also where one or more still undiscovered planets might orbit.
In essence, the study of the Proxima Centauri dust belts is also an indirect way to look for more planets. Guillem Anglada and his team intend to request further longer observations with the ALMA radio telescope to get more details on that system. The search is far from over!