Guillem Anglada-Escude of Queen Mary University of London is one of the driving forces in finding the nearest planets to Earth. Last year, he and his Pale Red Dot collaborators announced the discovery of Proxima Centauri b, the absolute nearest (potentially) habitable exoplanet to Earth, orbiting our nearest neighboring star. Pale Red Dot has since become RedDots, and is searching for additional planets at Proxima Centauri, as well as looking for planets at Ross 154 and Barnard’s Star, the latter being a sort of “holy grail” of nearby stars in planetary hunts.Anglada-Escude is a coauthor on a paper today by a team led by the completely-unrelated-at-all-but-same-named Guillem Anglada regarding the presence of several rings of dust. Anglada-Escude (not to be mistaken for Anglada) talked to us about the ring finding, what it means for nearby planets, and what the next steps are in our quest to understand the Proxima Centauri system — and maybe find a few more planets along the way.This comes after the discovery of the planet last year, or even before it was announced that people in Granada, which has a very good group in millimeter and submillimeter [radio astronomy]. [T]here’s some evidence in other systems that when there are close-in planets, there tend to be dust belts in long period orbits. That was the obvious thing, to see if there was a dust belt. To our surprise, no one had tried this before, so we asked for some ALMA time. The observation was carried out, and we got the first confirmation that there was some excess signal from the star, and things followed from there.

LCO/ESO/ESA/NASA/Y. Beletsky/M. Zamani

How do rings like this indicate the presence of a planet? Are planets shepherding the dust belts into that area?



It’s a bit like our solar system. When you see dust belts and smaller particles, it’s an asteroid belt. What’s probably there is an asteroid belt like our own, or several of them. We can confirm that there’s a three ring structure, so if that’s the case, it means there are objects that are probably shepherding all this dust and asteroids and they’re staying there. It’s not that they put the dust there. It’s that these orbits are stable over long timescales.



It’s like Saturn’s rings. You have structure, and you have gaps where the orbit is unstable and the dust remains where it’s comfortable.



Do you have any preliminary indication of these planets through RedDots?



From the radial velocity, we don’t see evidence of a long period gas giant. What we see is evidence is that maybe there is something there, but we need more radial velocity measurements.



There is evidence of an object at half an astronomical unit (AU), but this is very tentative. It’s not confirmed, but we committed to putting the data to the public. At this point, there’s a signal there, but we’re not sure if it’s caused by stellar activity or the presence of a planet or something else happening there.



In the dust paper, there seems to be a point source at 1.6 AU. We don’t see evidence for anything in the radial velocity there. That doesn’t mean there’s nothing there, just that the radial velocity is not attuned to an object there, which makes it unlikely that there’s a gas giant there.



With a planet at 0.5 AU, does that interact with the warm dust you saw at 0.4 AU?



That would be the expectation. This object might be one of the shepherd objects that shapes the ring if the object is real. This first paper is a preliminary snapshot, just reporting the evidence that there of these rings, and that the detection is very strong, but we still don’t know the structure of these rings. But there are several hints because this is a discovery process. Now we have to see if this planet is there, and we need a better picture of the rings to see what they have, and as the pieces of the puzzle come together, we’ll see progress.

