The newly discovered magnetar, a dense remnant of a once-bright star with an extremely strong magnetic field, is located in the galaxy M82 (known as “Cigar”), approximately 12 million light-years from Earth.
Sometimes called the universe’s most powerful magnets, magnetars are fast-spinning, intensely magnetized versions of neutron stars — the remnants of supernova explosions — that shine thousands of times brighter than the Sun, Live Science reports.
However, their eruptions are so short-lived and unpredictable that they are inconvenient objects to study. Only three other magnetar eruptions have been recorded during the last 50 years.
In mid-November 2023, the Integral telescope of the European Space Agency (ESA) detected a short-lived sudden burst of gamma rays in the direction of M82. Similar radiation also erupts during the birth of black holes, mergers of spinning neutron stars, and other exotic phenomena unrelated to magnetars.
“We immediately understood that it was something special.” Gamma-ray bursts come from a great distance and anywhere in the sky, but this one came from a bright nearby galaxy,” says Sandro Mereghetti of the National Institute of Astrophysics in Italy.
Further observations by telescopes in space and on Earth a few hours later localized the position of the flash within M82. Instead of the excruciating afterglow and gravitational waves expected in a normal gamma-ray burst, astronomers saw only hot gas and stars, confirming that the flash came from a magnetar.
A so-called “starquake,” when the intense magnetic fields of a magnetar interrupt a star’s rotation and disrupt its outer layers, ruptured the star’s surface and spewed high-energy gamma rays across space.
If the follow-up observations had been made only a day later, we would not have had such strong evidence that it was indeed a magnetar, said Jan Uwe Ness from ESA.
The latest discovery is in addition to three magnetars already found in our galaxy. Notable among them is the one observed in 2004, which, although halfway across the galaxy, was close enough that its radiation briefly flooded our planet and temporarily stopped several spacecraft. The newly discovered magnetar, on the other hand, is so far away that impact on Earth is extremely unlikely.
