Proxima Centauri never ceases to amaze us. The ALMA Observatory located in Chile has detected cold dust around the star closest to the solar system, Proxima Centauri, which reveals the first indication that this star has a much more complex planetary system than we previously thought. This outer belt of cold dust, which is a few hundred million kilometers from Proxima Centauri, could be made of rock and ice particles that were unable to form planets.
Regarding the star, Proxima Centauri is a faint red dwarf located just 4 light years distant from Earth in the southern constellation Centaurus (The Centaur). The temperate world Proxima b, discovered in 2016, orbits this star, making it the closest planet to the solar system. But, in light of this ALMA discovery, this system is not made up of a lonely planet.
According to the study, led by the Spanish researcher Guillem Anglada from the Institute of Astrophysics of Andalusia (Spain) , the mass of the cold dust found is one hundredth of the mass of the Earth, and the dust and rock particles would have an estimated temperature of -230ºC approximately, as cold as those of the Kuiper belt in the outer solar system.
“The dust around Proxima is important because, after the discovery of the terrestrial planet Proxima b, it is the first indication of the presence of a complex planetary system (made up of more than a single planet) around the star closest to our Sun” explains Anglada.
The dust belts we refer to are the remnants of material that did not form larger bodies, such as planets. The rock and ice particles in these belts range in size from the smallest dust grain – smaller than a millimeter across – to asteroid-like bodies many kilometers across.
In the ALMA data there are indications of a second belt of cold dust, located ten times further away. If confirmed, the nature of an outer belt ‘is intriguing’, given its cold environment and far from a star that is colder and weaker than the Sun. Both belts are much farther from Proxima Centauri than the planet Proxima b, orbiting just four million kilometers from its parent star.
“This result suggests that Proxima Centauri may have a multi-planet system with a rich history of interactions that resulted in the formation of a dust belt,” says Anglada.
Scientists hope that future studies from now on will help collect new data in order to identify possible additional, yet undetected planets.
A very interesting planet
The Proxima Centauri planetary system is also particularly attractive because there are plans, (the Starshot project, without going any further), for future direct exploration of the system with microprobes connected to laser actuated sails. Here, knowledge of the dusty environment around the star is essential for planning such a mission. So we are only at the beginning:
“These first results show that ALMA can detect dust structures orbiting Proxima. Additional observations will give us a more detailed picture of the Proxima planetary system. In combination with the study of protoplanetary disks around young stars, they will be given to to know many of the details of the processes that led to the formation of the Earth and the Solar System about 4.6 billion years ago. What we are seeing now is only the aperitif compared to what is coming! “, highlights Pedro Amado, co-author from work.
Referencia: ALMA Discovery of Dust Belts Around Proxima Centauri”, by Guillem Anglada et al., to appear in Astrophysical Journal Letters 2017
