Mystery deepens: Radio signals from extremely slow neutron star discovered
Fast-spinning neutron stars send pulsating radio signals. If they become too slow, they should disappear. However, this does not always seem to be the case.
(Image: University of Manchester)
An international research group may have found the slowest neutron star by far; it takes more than twice as long to complete one revolution as the previous record holder. The University of Manchester has made this public and explained that the characteristic radio signals of the celestial body are repeated every 54 minutes. Neutron stars are known to take only seconds or even fractions of a second to complete a revolution. It is therefore not entirely certain what ASKAP J193505.1+214841.0 is. As the team admits, the possibility that the source of the signal is a white dwarf star with an exceptionally strong magnetic field could not be ruled out. However, this is less plausible due to other circumstances.
Such a slow radio source should not be possible
The extreme neutron star was discovered with the ASKAP radio telescope in Australia, when it was actually being used to look for gamma rays and fast radio bursts (FRB). Subsequent analyses with the MeerKAT radio telescope network revealed that the strange object emits three fundamentally different types of signals. If they did not come from a single point at night sky, the group would not have believed that they came from a single object, study leader Manisha Caleb from the University of Sydney explains. This is therefore around 16,000 light years away from Earth. Further measurements will now help to determine the exact nature of the strange object. However, the discovery is first presented in the scientific journal Nature Astronomy.
Periodically recurring signals from neutron stars or magnetars with their particularly intense magnetic fields result from the intrinsic rotation of celestial bodies. As soon as they slow down too much, the signal disappears. Until recently, we only knew of signals that repeated themselves within a few minutes at most. Then, two and a half years ago, a "downright spooky" object was discovered that became one of the brightest radio sources in the sky for about a minute every 18 minutes. A year and a half later, a signal was discovered that only appears in the sky for five minutes every 22 minutes. In both cases, it was unclear what it was. The origin of such long-period signals is a great mystery, according to the discovery of the next record holder. Its discovery will deepen our understanding of the most mysterious objects in the universe.
(mho)