Astronomers have noticed a record-breaking flash of X-rays brought on by a thermonuclear explosion in house, which launched as a lot power in 20 seconds because the solar does in round 10 days.
The blast occurred on the floor of a pulsar—a quickly rotating neutron star with highly effective magnetic fields that shoots out beams of radiation from its poles, typically likened to an interstellar lighthouse. Neutron stars are the extremely dense remnants of stars which have exploded as supernovae after working out of gasoline towards the tip of their lives.
The pulsar in query—often called SAX J1808.4-3658 (or J1808 for brief)—is positioned round 11,000 light-years away within the constellation Sagittarius, spinning away at a staggering 401 rotations per second, in accordance with NASA.
On August 20, astronomers detected a sudden spike of X-rays originating from J1808 at round 10 p.m. utilizing NASA’s Neutron star Interior Composition Explorer (NICER) telescope on the International Space Station.
NASA says that that is the brightest X-ray burst ever detected by NICER for the reason that telescope started working in 2013. Furthermore, it produced a number of phenomena which have by no means been seen collectively in a single flash, in accordance with a examine printed in The Astrophysical Journal Letters.
“This burst was outstanding,” Peter Bult, lead writer of the examine from NASA’s Goddard Space Flight Center in Greenbelt, Maryland, and the University of Maryland, College Park, mentioned in an announcement.
Among probably the most uncommon parts of the explosion, the astronomers noticed that there was a brief pause within the enhance of X-ray brightness. Following this pause, the X-rays began to turn out to be brighter once more. The scientists aren’t clear precisely why this occurred however have proposed a possible clarification.
“We see a two-step change in brightness, which we think is caused by the ejection of separate layers from the pulsar surface, and other features that will help us decode the physics of these powerful events,” Bult mentioned.
The sort of thermonuclear explosion that the scientists noticed is called a Type I X-ray burst. These phenomena happen within the floor layers of neutron stars which accumulate hydrogen and/or helium from a companion star.
In the case of J1808, the pulsar is a part of a binary (twin) star system the place the opposite physique is a brown dwarf—a category of astronomical objects bigger than large planets however too small to be stars.
The excessive gravitational pull of the pulsar sucks in hydrogen fuel from the brown dwarf, which accumulates in a disk across the dense star remnant.
Every few years, this fuel disk across the pulsar turns into so dense that atoms within the fuel lose their electrons, or in different phrases, they turn out to be “ionized.”
This causes radiation to turn out to be trapped, beginning a runaway technique of heating and extra ionization. Eventually, the hydrogen fuel begins spiralling downwards into the pulsar, forming a scorching “global sea.”
When temperatures and pressures on the backside of this ever-deepening sea enhance to a excessive sufficient level, hydrogen nuclei start to fuse and type helium nuclei, producing huge quantities of power. This course of is similar because the one which takes place within the core our Sun, fueling the star.
“The helium settles out and builds up a layer of its own,” co-author of the paper Zaven Arzoumanian from Goddard mentioned in an announcement. “Once the helium layer is a few meters deep, the conditions allow helium nuclei to fuse into carbon. Then the helium erupts explosively and unleashes a thermonuclear fireball across the entire pulsar surface.”