One of the easiest pits to fall into as an astronomer is designing surveys to see what is expected and thus totally missing what’s unknown. This was a trap that a team of researchers using the MeerKAT telescope to look for transients and pulsars almost fell into. With their instrument – named MeerTRAP – mounted alongside another imaging instrument, they were looking for your standard, high-speed events — stars spinning hundreds of times a second, bursts that last the briefest of moments. Essentially, they were looking for radio blips that tell stories of the low-energy side of the universe.

And when you are looking for things that can happen hundreds of times a second, you don’t normally look at any one object all that long. Unless you’re ridesharing with an imaging instrument intent on staring at things.

It was in this kind of a piggyback, along-for-the-ride situation that MeerTRAP found a pulsar that rotates every 76 seconds. This rotational period is so slow that initial observations only caught one pulse. Previously, no pulsars had been spotted rotating this slow.

It is unclear if the lack of prior detections is due to this being a rare object or our own lack of patience.

These results are published in Nature Astronomy with first author Manisha Caleb, who explains: Amazingly we only detect radio emission from this source for 0.5% of its rotation period. This means that it is very fortuitous that the radio beam intersected with the Earth. It is therefore likely that there are many more of these very slowly spinning sources in the Galaxy which has important implications for how neutron stars are born and age. The majority of pulsar surveys do not search for periods this long and so we have no idea how many of these sources there might be. In this case, the source was bright enough that we could detect the single pulses with the MeerTRAP instrument at MeerKAT.

This means that alongside the crazy fast, never-ending drumroll of your standard pulsar, we now know there are lumbering stars, more lazily keeping a slower beat.

And we have to wonder what else are we missing because we just don’t look slowly enough?

More Information

SARAO press release

“Discovery of a radio-emitting neutron star with an ultra-long spin period of 76 s,” Manisha Caleb et al., 2022 May 30, Nature Astronomy