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on august 21st 2019 nasa's nicer

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telescope on the international space

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station observed its brightest x-ray

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burst to date

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the flare-up came from saks j1808 a

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binary system about 11 000 light years

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away

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here a pulsar a rapidly spinning neutron

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star draws gas from its companion an

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object called a brown dwarf that is

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larger than a planet but less massive

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than a star

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hydrogen gas from the brown dwarf forms

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an accretion disk around the pulsar

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every few years the disk becomes

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unstable

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this sends a rush of gas toward the

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pulsar that makes it brighten and x-rays

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the pulsar super-strong magnetic field

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sweeps up the gas and channels it to the

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object's surface

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hydrogen nuclei falling to the pulsar

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surface fuse together producing energy

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and forming helium nuclei which settle

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out below

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this process is similar to what happens

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inside our sun

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then when the conditions are just right

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the entire helium layer ignites in a

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brief but intense thermonuclear fireball

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astronomers call this a type 1 x-ray

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burst here's how it happened

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the explosion first blows off the

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hydrogen layer which expands and

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ultimately dissipates

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then the rising radiation builds to the

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point where it blows off the helium

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layer which overtakes the hydrogen shell

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some of the x-rays emitted in the blast

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scatter off of the accretion disk

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the fireball then quickly cools and the

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helium settles back onto the surface

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it was all over in 20 seconds but nicer

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data clearly show important details that

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haven't been seen together in other

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bursts

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this will help scientists better