• The magnetar SGR 0501+4516 is traveling through the Milky Way at an unexpectedly high speed, disproving initial theories linking its origin to the supernova remnant HB9.
• The unusual trajectory suggests alternative formation pathways for magnetars, such as the collapse of a white dwarf or the merger of neutron stars, rather than the traditional core-collapse supernova.
• Understanding the formation of SGR 0501+4516 could provide insights into other extreme cosmic events, like fast radio bursts and gamma-ray bursts, and potentially explain FRBs originating from old stellar regions.

Astronomers have been studying SGR 0501+4516, a magnetar discovered in 2008, and have found that its high speed and trajectory through the Milky Way are inconsistent with the prevailing theory that magnetars form from core-collapse supernovae. The initial assumption was that SGR 0501+4516 originated from the nearby supernova remnant HB9, but new data from the Hubble Space Telescope and the Gaia spacecraft indicates otherwise. This discovery challenges our understanding of magnetar formation and opens up possibilities for alternative formation mechanisms.

• What: SGR 0501+4516, a magnetar with an extremely powerful magnetic field, is moving through the Milky Way at a speed inconsistent with the theory that it originated from the supernova remnant HB9.
• Who: Ashley Chrimes (ESA), Joe Lyman (University of Warwick), Andrew Levan (Radboud University and University of Warwick), Nanda Rea (Institute of Space Sciences in Barcelona), Hubble Space Telescope, Gaia spacecraft.
• When: Magnetar first discovered in 2008. The new study was published April 15 in Astronomy & Astrophysics. Observations span a decade.
• Where: Milky Way galaxy, with SGR 0501+4516 located near the supernova remnant HB9.

The discovery that SGR 0501+4516's trajectory doesn't align with HB9 challenges the long-held assumption that magnetars are formed exclusively from core-collapse supernovae. This opens up new avenues for research into alternative formation mechanisms, such as the direct collapse of a white dwarf or the merger of two neutron stars. The implications extend to our understanding of other high-energy astrophysical phenomena, especially fast radio bursts (FRBs). If magnetars can form without supernovae, it could explain FRBs originating from older stellar populations.

"Normally, the [supernova] scenario leads to the ignition of nuclear reactions, and the white dwarf exploding, leaving nothing behind. But it has been theorized that under certain conditions, the white dwarf can instead collapse into a neutron star. We think this might be how [this magnetar] was born."

"Magnetar birth rates and formation scenarios are among the most pressing questions in high-energy astrophysics, with implications for many of the Universe's most powerful transient events, such as gamma-ray bursts, superluminous supernovae, and fast radio bursts."

All the movement we measured is smaller than a pixel in a Hubble image. Being able to make these measurements demonstrates Hubble’s exceptional long-term stability.

The perplexing origins of SGR 0501+4516 continue to challenge established magnetar formation models. Its unusual velocity and trajectory suggest formation pathways beyond conventional supernova explosions, potentially involving the direct collapse of a white dwarf or neutron star mergers. These alternative mechanisms could also shed light on the source of fast radio bursts, particularly those originating from older stellar populations. Further investigation, utilizing facilities like the Hubble Space Telescope, is crucial to explore the diverse origins of magnetars and their connections to high-energy cosmic phenomena, including the potential role of giant flares in the creation of heavy elements.