Astronomers measure a 1-billion tesla magnetic field on the surface of a neutron star

We recently observed the strongest magnetic field ever recorded in the Universe. The record-breaking field was discovered at the surface of a neutron star called GRO J1008-57 with a magnetic field strength of approximately 1 BILLION Tesla. For comparison, the Earth’s magnetic field clocks in at about 1/20,000 of a Tesla – tens of trillions of times weaker than you’d experience on this neutron star…and that is a good thing for your general health and wellbeing.

Why do neutron stars have incredibly powerful magnetic fields? Seems counterintuitive given that they are made of neutrally charged particles (where neutron gets its name). Well, if you were to cut away a neutron star, it is formed of several layers. A cloud of remaining electrons near the surface, further down traces of charged “impurities” of various atomic nuclei remaining after the formation of the neutron star, a crust of neutrons, and a core of a theorized frictionless neutron fluid further mixed with impurities. The combination of layers makes the star incredibly conductive. Spin a very conductive object and you create a churning flow of charged particles which generates a powerful magnetic field. Our planet’s own magnetic field is itself created by the rotation of the Earth’s nickel-iron core. However, neutron star rotations are astonishingly fast. The first neutron star discovered had a rotation period of 1.33s.

But how can we measure the strength of a pulsar’s magnetic energy? A special technique can be used with a specific class of pulsars which GRO J1008-57 belongs to called accretion powered X-Ray pulsars. GRO J1008-57, about 20,000 light years from Earth, is actually in a binary gravitational relationship with a living class B companion star. B’s are hefty stars, a dozen or so times the mass of our Sun and thousands of times brighter. GRO J1008-57’s super density creates a powerful gravitational pull 100 billion times more powerful than Earth’s which rips stellar material off its companion. That material falls toward the neutron star. It becomes entangled in the neutron star’s magnetic field flowing along the “lines” of that field to the north and south magnetic poles where it accumulates or accretes on the surface.

The stellar material slams into the surface at half the speed of light releasing tremendous X-Ray energy. These X-Rays, before radiating away from the neutron star, pass through the magnetic field at the neutron star’s surface. The magnetic field scatters some of the X-Rays leaving a gap or “absorption line” in the spectrum of the X-Rays. It’s like a fingerprint left by the magnetic field on the X-Ray energy that we can see with our telescopes. Where that absorption line appears along the X-Ray spectrum directly relates to the strength of the magnetic field at the neutron star’s surface where the stellar material is falling. The line phenomenon is known as a Cyclotron Resonance Scattering Feature.

In 2017, the brightest X-Ray outburst ever observed from GRO J1008-57 was recorded by the Chinese Insight-HXMT satellite. A team of scientists from the Institute of High Energy Physics of the Chinese Academy of Sciences and Eberhard Karls University of Tübingen, Germany analyzed the Cyclotron abortion lines in the X-Ray spectrum received. The team recently announced they had discovered lines in the spectrum corresponding to a 1-billion Tesla magnetic field – the most powerful ever recorded in the Universe. Powerful enough to literally pull atoms apart. So, if it doesn’t vaporize you with its immense heat, or obliterating gravity, your atomic structure would basically dissolve in the magnetic forces.

Source: “Astronomers Measure a 1-billion Tesla Magnetic Field on the Surface of a Neutron Star” Universe Today, 17 September 2020

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