The dusty material might range in size from grains of only a few millimeters to asteroid-like bodies several kilometers across, study team members said. Dust belts like this are thought to be the remains of material that didn’t manage to clump together to form planets, they added.
ALMA also spotted signs of a possible second dust ring, about 10 times farther from the star than the other one, though this feature awaits confirmation. If the outer ring does indeed exist, its material would be very cold, lying so far from a star that is much smaller and dimmer than the sun.
The faint outer belt could prove useful to astronomers: Studying its shape could yield a better understanding of Proxima b's mass, which is not known very well at the moment, the researchers said.
RELATED: Proxima Centauri's Origins Could Mean Its Exoplanet Really Is Habitable
And then there's the exploration angle. The $100 million Breakthrough Starshot project aims to send sail-equipped, laser-driven microprobes zooming past Proxima b in the not-too-distant-future, and mapping out the system's dust environment could be key to the success of such a mission, study team members said.
"These first results show that ALMA can detect dust structures orbiting around Proxima. Further observations will give us a more detailed description of Proxima's planetary system," study co-author Pedro Amado, also from the Instituto de Astrofiscia de Andaluicia, said in the same statement. "What we are seeing now is just the appetizer compared to what is coming!"
The new study has been accepted for publication in Astrophysical Journal Letters.
Originally published on Space.com.
Proxima b: 6 Strange Facts About a Potentially Earth-Like Exoplanet
Alien Planet Quiz: Are You an Exoplanet Expert?
10 Exoplanets That Could Host Alien Life
WATCH: How We Find Water on Exoplanets