Giant Arecibo radio dish joins search for rocky planets around nearby stars

Last month, the Red Dots project launched with the aim of detecting the nearest terrestrial planets outside our Solar System. Institutions from the UK to Chile have been collaborating on this – and now two different organisations are joining the search.

The National Science Foundation’s Arecibo Observatory and the Planetary Habitability Laboratory, based at the University of Puerto Rico at Arecibo, lent their power to the collaboration last week to study Barnard’s Star, a red dwarf just over a tenth the mass of our Sun.

Around six light-years away from us, it’s our second-closest stellar system after the three stars making up the Alpha Centauri system and features prominently in science fiction. (Incidentally, Barnard’s Star’s motion across the sky is rapid enough that it can be detected in photos taken by amateur astronomers just a year apart.)

Barnard’s Star has also been the subject of some controversy; in the 1960s, astronomer Peter van de Kamp claimed to have found multiple Jupiter-sized planets orbiting the red dwarf. Although by the 1970s other astronomers had demonstrated that this was due to artifacts in data caused by maintenance and upgrade work, van de Kamp never admitted his error; as late as 1982, he claimed to have found two more planets.

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While further observations have ruled out the existence of planets with masses larger than 10 times that of Jupiter, or Jupiter-sized planets which take less than 1000 days to orbit Barnard’s Star, there’s still a tantalising possibility that rocky planets like our own could exist.

The Red Dots project is already hunting for planets at optical and infrared wavelengths, but the Arecibo Observatory is a radio telescope. Even though using a radio telescope to detect planets might seem counterintuitive, radio emissions could be used to build up a picture of a star’s environment, including perturbations which might indicate the presence of planets.

Just as taking photos of an object from different angles can help an observer to build a comprehensive model and bring new features to light, observing Barnard’s Star in multiple different wavelengths will deepen our understanding of our neighbour.

Regardless of whether the teams find terrestrial planets around Barnard’s Star or not, the collaboration between the Arecibo Observatory, the Planetary Habitability Laboratory and the Red Dots project will contribute towards organising future observation campaigns.

“Simultaneous observations with different facilities are difficult to organise, so this will be a rare opportunity to explore synergies for future campaigns,” writes Guillem Anglada-Escudé, an astronomer at Queen Mary, University of London and the leader of the group who discovered Proxima b.

In addition, the Red Dots project is releasing its data to the public and engaging with professional and amateur astronomers alike in order to increase participation. While the popularity of citizen science has exploded in recent years, the whole of the Red Dots project is being conducted as an “Open Notebook Science experiment”, where all data and experiment logs are made publicly accessible. This is still comparatively rare and it will be interesting to see the effects this has on public engagement.

The data will be published to the project’s open journal at https://reddots.space/. For now, whatever happens, this collaboration will have far-reaching consequences – and rightly so.

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