Exploding stars surrender their hearts' secrets to science

 

Using data from multiple telescopes across Europe and America, astronomers have been able to see into the center of an exploding star. The telescopes were used to obtain highly-detailed images, pinpointing where a stellar explosion (nova) took place, emitting gamma rays.

 

Gamma ray emissions were first observed in 2012 but scientists had no idea how they were produced, until they observed the nova explosion. In June that year, NASA’s Fermi spacecraft detected gamma rays from the V959 Mon nova.

 

At the same time, observations from the Karl G. Jansky Very Large Array (VLA) of telescopes in the US indicated that radio waves produced by the explosion were the result of magnetic fields interacting with subatomic particles moving at near-light speed. These particles were also needed for gamma-ray emission.

 

“We not only found where the gamma rays came from, but also got a look at a previously-unseen scenario that may be common in other nova explosions,” said Laura Chomiuk, of Michigan State University.

 

Observations from the European VLBI network (EVN) and the US Very Long Baseline Array (VLBA) revealed two different knots of radio emission. Combining this information with data from studies conducted using the e-MERLIN telescope array in the UK and further observations from the VLA, astronomers were able to reconstruct the creation of radio knots and gamma rays.

 

“By watching this system over time and seeing how the pattern of radio emission changed, then tracing the movements of the knots, we saw the exact behaviour expected from this scenario,” Chomiuk said.

 

Since 2012, Fermi has detected gamma rays from a total of three other nova explosions. (https://public.nrao.edu/news/pressreleases/nova-gamma-ray-mystery-unraveled) Astronomers speculate that the phenomenon is actually quite common, but may only be seen if the event occurs at a certain distance from earth.

 

“This mechanism may be common to such systems. The reason the gamma rays were first seen in V959 Mon is because it's close,” Chomiuk said. — TJD, GMA News