Enlarge / A slowly rotating neutron star is still our best guess as to the source of the mystery signals. (credit: Nazarii Neshcherenskyi)

Roughly a year ago, astronomers announced that they had observed an object that shouldn't exist. Like a pulsar, it emitted regularly timed bursts of radio emissions. But unlike a pulsar, those bursts were separated by over 20 minutes. If the 22-minute gap between bursts represents the rotation period of the object, then it is rotating too slowly to produce radio emissions by any known mechanism.

Now, some of the same team (along with new collaborators) are back with the discovery of something that, if anything, is acting even more oddly. The new source of radio bursts, ASKAP J193505.1+214841.0, takes nearly an hour between bursts. And it appears to have three different settings, sometimes producing weaker bursts and sometimes skipping them entirely. While the researchers suspect that, like pulsars, this is also powered by a neutron star, it's not even clear that it's the same class of object as their earlier discovery.

How pulsars pulse

Contrary to the section heading, pulsars don't actually pulse. Neutron stars can create the illusion by having magnetic poles that aren't lined up with their rotational pole. The magnetic poles are a source of constant radio emissions, but as the neutron star rotates, the emissions from the magnetic pole sweep across space in a manner similar to the light from a rotating lighthouse. If Earth happens to be caught up in that sweep, then the neutron star will appear to blink on and off as it rotates.