Scientists have admitted they are baffled by mysterious object which has been sending signals in the direction of Earth for at least 35 years.
The radio blasts fail to conform to any models which have been proposed so far in attempts to explain them.
The newly discovered source has been sending out regular 20-minute bursts of energy, varying significantly in brightness since 1988, according to a team of researchers.
The signals resemble those produced by pulsars, or fast radio bursts, which can last anything from a few milliseconds to several seconds.
However, by contrast in this case the source, named GPMJ1839-10, sends radio signals which pulsate on a period of 21 minutes – previously believed to be impossible.
Pulsars are neutron stars which spin extremely fast, throwing out multiple radio blasts in the process.
Emissions crossing the Earth can be picked up very briefly and brightly, in much the same way as a ship illuminated by the light from a rotating lighthouse.
Conventional scientific theories suggest such a process will only work if a pulsar’s magnetic field is strong, and provided it is spinning rapidly enough.
Scientists have developed the concept of the so-called “pulsar death line”, which theorises that such sources are only detectable provided they are spinning fast and strongly enough.
GPMJ1839-10 lies well beyond that death line, meaning that if it is a pulsar, then it seems to be behaving in ways which were previously unheard of.
Alternatively, it could a highly magnetised white dwarf or magnetar, a neutron star with an incredibly strong magnetic field. Researchers do not believe these objects emit signals like this however.
But they do not tend to send out emissions of this kind, researchers believe.
Despite having been detected on Earth for more than 30 year, they have gone unnoticed by those compiling the data, the report, A long-period radio transient active for three decades, published in the scientific journal Nature, concluded.
After they worked out the source, the researchers then realised the signals had been repeating for almost four decades.
Victoria M Kaspi, a professor of physics at McGill University who was not involved with the study, wrote in an accompanying article: “Only time will tell what else lurks in these data, and what observations across many astronomical timescales will reveal.”
