Scientists have discovered a magnetized dead star with a solid surface

X-ray light emitted by a particular magnetar (a highly magnetized dead star) indicates that the star has a solid surface and no atmosphere, according to a new study.

In a study published in the journal ScienceUsing data from NASA’s Imaging X-ray Polarimetry Explorer (IXPE) satellite, revealed that a highly magnetized dead star known as a magnetar has a solid surface without an atmosphere. The study, led by researchers from the University of Padua, represents the first observation of polarized X-ray light from a magnetar. This was the first observation of polarized X-ray light from a magnetar.

IXPE, a joint project between NASA and the Italian Space Agency, allows scientists to study X-ray light in space by measuring its polarization – the direction in which light waves oscillate. The team studied magnetar 4U 0142+61, located about 13,000 light-years from Earth in the constellation Cassiopeia.

Magnetars are neutron stars that are very dense remnants of the cores of massive stars that explode as supernovae at the end of their lives. Unlike other neutron stars, they have the strongest magnetic field in the universe. They emit bright X-rays and exhibit periods of erratic activity, emitting flames and flares that can release in just a second an amount of energy millions of times greater than the energy emitted by our Sun in a year. They are thought to be powered by their super-strong magnetic field, which is 100 to 1000 times stronger than normal neutron stars.

The research team found a much lower fraction of polarized light than would be expected if X-rays passed through the atmosphere. (Polarized light is light in which everything moves in one direction, meaning electric fields vibrate in only one direction. The atmosphere acts as a filter, selecting only one polarization state of the light.)

The team also found that for particles of light at higher energies, the angle of polarization – the wobble – changes exactly 90 degrees compared to light at lower energies, which theoretical models would predict whether the star has a solid shell surrounded by an outer layer. layer. magnetosphere filled with electric currents.