Astronomers have long studied dying stars because they hold crucial information about our universe and they make some mesmerizing images.
Now, research on a dead star on the edge of the Milky Way may have produced evidence of a type of gargantuan thermonuclear explosion that's never been seen before, as reported by Live Science last Friday.
The event may take 1,000 years to occur again which means it will never be seen again in our lifetime.
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A gargantuan explosion
The explosion took place in 2011 and released in three minutes the same amount of energy as our sun releases in 800 years. The researchers named the explosion a "hyperburst."
"For any type of thermonuclear explosion, you need very high temperatures and very high pressure," study co-author Jeroen Homan, a research scientist at Eureka Scientific in Oakland, California, told Live Science. "For a hyperburst, the temperature and pressure requirements are so high that we think it may only occur in a particular source once in 1,000 years."
The hyperburst occurred deep within a neutron star; it is the result of hundreds or thousands of years of heat and pressure building up.
A particular flare-up
The star that produced this flare-up is called MAXI J0556–332. In 2011, when the researchers first spotted it they knew right away that something about this particular explosion was different.
"During the first week after the outburst ended, we noticed that this star was incredibly hot," Homan said. "About twice as hot as any other star that we've observed before."
After 10 years of carefully studying the neutron star, the team concluded that they had discovered a thermonuclear explosion that occurred deep in the neutron star as the result of the nuclear fusion of oxygen or neon.
"This would be the first observation of a hyperburst," Homan added.
Their study, which is not yet peer-reviewed, was published on February 9 on the preprint server arXiv.
The study of transiently accreting neutron stars provides a powerful means to elucidate the properties of neutron star crusts. We present extensive numerical simulations of the evolution of the neutron star in the transient low-mass X-ray binary MAXI J0556–332. We model nearly twenty observations obtained during the quiescence phases after four different outbursts of the source in the past decade, considering the heating of the star during accretion by the deep crustal heating mechanism complemented by some shallow heating source. We show that cooling data are consistent with a single source of shallow heating acting during the last three outbursts, while a very different and powerful energy source is required to explain the extremely high effective temperature of the neutron star, ∼ 350 eV, when it exited the first observed outburst. We propose that a gigantic thermonuclear explosion, a “hyperburst” from unstable burning of neutron rich isotopes of oxygen or neon, occurred a few weeks before the end of the first outburst, releasing ∼ 1044 ergs at densities of the order of 1011 g cm−3. This would be the first observation of a hyperburst and these would be extremely rare events as the build up of the exploding layer requires about a millennium of accretion history. Despite its large energy output, the hyperburst did not produce, due to its depth, any noticeable increase in luminosity during the accretion phase and is only identifiable by its imprint on the later cooling of the neutron star.