Research: Magnetized dead star has solid surface
Padova, Italy: The research, headed by scientists at the University of Padova and published in the journal Science, makes use of information from the Imaging X-ray Polarimetry Explorer (IXPE), a NASA satellite that was launched in December of last year.
By detecting polarisation, or the direction of the light waves' wobble, the satellite--a joint project of NASA and the Italian Space Agency--offers a fresh perspective on X-ray photons in space.
The group examined the magnetar 4U 0142+61 observation from IXPE, which is situated around 13,000 light years from Earth in the Cassiopeia constellation. It had never before been possible to see polarised X-ray photons coming from a magnetar.
The extremely dense remaining cores of massive stars that have burst as supernovae at the conclusion of their lives are known as magnetars. They have a huge magnetic field, the strongest in the cosmos, unlike other neutron stars.
They produce brilliant X-rays and exhibit irregular activity, emitting bursts and flares that can discharge energy millions of times higher than what our Sun releases in a year in just one second. They are thought to be propelled by their extraordinarily strong magnetic fields, which are 100-1,000 times stronger than those of typical neutron stars.
When compared to what would be predicted if the X-rays went through an atmosphere, the research team discovered a far smaller fraction of polarised light. (Polarized light is light in which the electric fields vibrate only in one direction, or in which the wiggle is completely in one direction.)
An atmosphere serves as a filter, limiting the light's polarisation states to one.) The team also discovered that for light particles with higher energies, the angle of polarisation, or the "wiggle," flipped by exactly 90 degrees in comparison to light with lower energies, as predicted by theoretical models for stars with solid crusts encircled by magnetospheres that are filled with electric currents.
Co-lead author Professor Silvia Zane (UCL Mullard Space Science Laboratory), a member of the IXPE science team, said: "This was completely unexpected. I was convinced there would be an atmosphere. The star's gas has reached a tipping point and become solid in a similar way that water might turn to ice. This is a result of the star's incredibly strong magnetic field.
"But, like with water, the temperature is also a factor - a hotter gas will require a stronger magnetic field to become solid.
