Neutron Stars

Starquakes Are Real, Jaw-Dropping, And Surprisingly Informative

When a starquake happens, scientists get excited. These explosions in space reveal information about stars that's helping us unravel the mysteries of the solar system. The key is in a kind of light you've seen at the dentist and if you've ever broken a bone: X-rays.

Artist's conception of a gamma-ray flare expanding from a starquake on magnetar SGR 1806-20.

Starquakes

Scientists are still learning about starquakes, but one in particular stands out: the massive quake observed 50,000 light years away in the neutron star known as SGR 1806-20, back in December 2004. Neutron stars like that one are the leftovers of a huge star caving in on itself at the end of its life, so they're extremely dense with a strong gravitational pull. Although the stars themselves are small enough to fit in a medium-sized city, a teaspoonful of neutron star matter would weigh at least a billion tons on Earth.

When the starquake on SGR 1806-20 happened, it released a flash of energy lasting about a tenth of a second but adding up to "more energy than the Sun emits in 150,000 years," according to Space.com. The flash was brighter than anything ever seen from beyond our solar system.

But why did it happen in the first place? Scientists believe it was caused by an abrupt change in the star's magnetic field. A neutron star's intense magnetic field is locked to its solid crust, so a change in one leads to a change in the other—meaning all of that incredibly dense matter went crack. The result? A massive starquake.

X-Rays: For More Than The Doctor's Office

The data taken during starquakes like the SGR 1806-20 allows scientists to measure light waves they wouldn't be able to observe otherwise. "Astronomers use light of all wavelengths to understand the nature of the universe," writes Fiona Harrison, Ph.D., physicist with NASA and Caltech. X-ray astronomers, though, specifically focus on that one part of the electromagnetic spectrum to take measurements of celestial bodies.

"Regions that glow in X-rays range from the largest objects in the Universe that are held together by gravity, called galaxy clusters, to the most compact objects, like black holes and neutron stars," Harrison writes. X-rays allow scientists to learn more about what might make up the inside of the neutron stars they're measuring, and how thick the crust might be, based on the waves emitted.

Scientists continue to turn to X-rays to advance knowledge about neutron stars. In fact, in June 2017, NASA announced the first neutron star mission, called NICER. It'll include what they're calling "the world's first demonstration of X-ray navigation in space." For 18 months, a payload attached to the International Space Station and made of X-ray mirrors will closely observe neutron stars for starquakes and other phenomena such as thermonuclear explosions. NASA says they even hope to learn about the possibility of X-ray communications during this mission, which would be helpful in future space exploration.

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Written by Ashley Hamer June 16, 2017