The radio signal itself, detected in spring 2019 and reported on earlier in The Guardian, is in many ways the stuff of dreams for alien hunters. It was a narrow-band signal with a frequency of 982.02 MHz as recorded at the Parkes Observatory in Australia. Nature, whether an exploding star or a geomagnetic storm, tends to broadcast on a wide range of frequencies.

“The signal appears to only show up in our data when we’re looking in the direction of Proxima Centauri, which is exciting,” Ms. Sheikh said. “That’s a threshold that’s never been passed by any signal that we’ve seen previously, but there are a lot of caveats.”

Practitioners of the hopeful field of the search for extraterrestrial intelligence, also known as SETI, say they have seen it all before.

“We’ve seen these types of signal before, and it’s always turned out to be R.F.I., radio frequency interference,” Dan Werthimer, chief technologist at the Berkeley SETI Research Center, who is not part of the Proxima Centauri study, wrote in an email.