Astronomers Stumped By Enigmatic Magnetar That Has Just Awoken After A Decade Of Slumber

ESO/L. CalçadaWikimedia Commons/Cropped and Resized

A rare type of neutron star has thrown astronomers for a loop after suddenly waking up following years of inactivity. The star in question is a magnetar, a special kind of neutron star that boasts an extremely powerful magnetic field and emits X-rays and gamma rays.

Dubbed XTE J1810–197, this particular magnetar is an oddball among an already strange class of neutron stars. According to Science Alert, this is one of the rarest stars known to science. First discovered in 2004, it is not only one of just 23 magnetars found to date, but it’s also part of an “exclusive club of weird stars” — XTE J1810–197 is one of just four highly magnetic magnetars known to emit radio waves.

As The Inquisitr previously reported, neutron stars are small, highly condensed cores of dead stars that cram a large amount of stellar mass – equivalent to about two times that of the sun – into a space comparable to the size of a large city. Aside from black holes, these are the densest type of object that we’ve detected in the universe, explains Live Science.

Magnetars are fast-spinning, highly magnetized neutron stars that spew out high-energy electromagnetic radiation. This radiation is detected from Earth in the form of regular flashes of energy, emitted as the magnetars spin around in space, and is fueled by their formidable magnetic fields — about a million times more intense than those of typical neutron stars. Compared to Earth’s magnetic field, a magnetar’s field is a quadrillion times more powerful, notes Space.

Artist’s impression of a magnetar.Featured image credit: ESO/L. CalçadaWikimedia Commons/Resized

Aside from these bright flashes of energy, some – very rare – magnetars also give off radio waves, as is the case with XTE J1810–197. However, the star went quiet about 10 years ago, slipping into a prolonged, inexplicable slumber from which it has now awoken.

After going dormant in late 2008, the magnetar began beaming radio waves once again on December 8, 2018. Its sudden outburst of activity was picked up by astronomers from the University of Manchester in the U.K. and the Max Planck Institute of Radio Astronomy in Germany, who published their findings on the preprint server arXiv.

The team has been monitoring this peculiar star ever since it went silent, constantly scrutinizing it with a radio telescope. While the scientists are unsure why the magnetar’s radio waves have picked up again, or why the star went into radio silence in the first place, they did notice that XTE J1810–197 was behaving differently after its slumber. In other words, it didn’t wake up the same as it was when it went to sleep, exhibiting a different profile of radio waves as it did between 2004 and 2008.

Artist’s impression of a magnetar in the very rich and young star cluster Westerlund 1.
Artist’s impression of a magnetar in the star cluster Westerlund 1, found 15,000 light-years away in the constellation of Ara ('The Altar').Featured image credit: ESO/L. CalçadaWikimedia Commons/Resized

Interestingly enough, the magnetar awoke with a new rhythm of radio waves that appears to be calmer and more relaxed than before.

“When XTE J1810–197 last flashed across human telescopes, it acted erratically, wildly shifting its pulse profile over relatively short time periods,” Live Science reported, adding that the rhythm of its radio waves is more stable, per the newly published paper.

“The pulse variations seen so far from the source have been significantly less dramatic, on timescales from hours to months, than seen in 2006.”

In addition, the team discovered that the magnetar now has a much greater spinning torque, something previously observed in another type of fast-rotating neutron stars – pulsars – following a dormant period.

According to Science Alert, some theories suggest that magnetars might actually start out as pulsars — as neutron stars begin spinning at hundreds to thousands of times per second, these stars first turn into a pulsar and then become a magnetar. This could also account for the powerful magnetism of these puzzling stars.