What causes these giant explosions that rock the universe?
At the heart of a stellar quake is a neutron star, which has a highly dense mass of protons and electrons that have been forced together to form neutrons.
Neutron stars have up to five times the mass of the Sun but are only about 20 kilometres (12.4 miles) in diameter.
They spin on average at 400 rotations per second, but their strong magnetic fields cause them to slow down overtime. The highest observed spin speed of a neutron star is 1,122 rotations per second.
As they rotate, the incredibly strong gravitational force of the star counteracts the spin of the star. The former attempts to draw in the equator, while the centrifugal forces resulting from the spin of the star try to push the equator out. This changes its shape from an oblong to a sphere, cracking the rigid iron crust. Mountains only a few centimetres tall begin to appear across the surface as the tension builds.
Eventually, the tension in the surface reaches such a level that the crust “snaps’ and a huge number of gamma-rays and x-rays are released as a stellar quake. As the geometry of the star readjusts, the strong magnetic fields temporarily drop to a lower energy level. Combined with the energy released from inside the star, this creates one of the largest known flashes of x-rays in the universe.
Recent evidence suggests the primary causes of the largest stellar quakes are magnetars, large neutron stars with an incredibly powerful magnetic field. At twice the size of a regular neutron star, a magnetar can have up to 30 times more mass than the Sun, despite the Sun being 46,000 times larger. Atablespoon of mass from a magnetar would weigh the same as 274 Empire State buildings. The magnetic field of a magnetar is several trillion times stronger than that of Earth while its rigid crust is 10 billion times stronger than steel and 1.5km (0.9 miles) thick.
A massive stellar quake was detected 50,000 light years from Earth on 27 December 2004, the biggest explosion observed by humans since a supernova in 1604. Scientists said that if it had been 10 light years closer, we would have been facing a mass extinction.
Top 3 explosions in the Universe
1. Supernova – Over the course of just a few weeks a supernova will emit as much energy as the Sun in its 10 billion year lifetime.
2. Stellar quake – Stellar quakes more than 10,000 times weaker than a gamma-ray burst are described as soft gamma-ray emissions.
3. Gamma-ray burst – As a star goes supernova, a gamma-ray burst releases as much energy in a second as the Sun in its entire lifetime.