NASA telescope captures star switching on and off

NASA telescope captures star switching on and off ...

Deep within the cosmos, a fading star's quiet death was abruptly interrupted. Instead of gracefully disappearing into the dark of space, as stars do, it coughed out a strange, prolonged flicker of light.

Simone Scaringi, an astronomer at Durham University's Centre for Extragalactic Astronomy in the United Kingdom, stated in a statement that the discovery "has never been seen in other accreting white dwarfs." It seems to be switching on and off. Scaringi is the lead author of a study on the star published Monday in the journal Nature Astronomy.

Every iridescent star that decorates our universe -- and those yet to be added to the glittering collection -- will one day vanish. Slowly but surely, their glow, fueled by heaps of hydrogen gas, will diminish as the supply runs out. At their final stages of life, they will be called white dwarfs.

And NASA's Transiting Exoplanet Survey Satellite, or TESS, provided a unique glimpse of this particular white dwarf'd strange behavior. The dying star is part of the TW Pictoris Two-Star System, which is located 1,400 light-years away.

"To witness the brightness of TW Pictoris drop in 30 minutes is, in itself, astonishing," Scaringi said. His team believes the star lost illumination unexpectedly because of a sudden problem in its food-funneling mechanism. Basically, the shiny space ball's fiery snacks were out of reach.

White dwarfs feast on their companion stars by pulling fiery bits of the body into their Saturn-like ring of matter, or accretion disc, held in place by suspended magnetic fields. Swallowing a delicious bite of bread can literally make swans fly with glee.

However, these glinting orbs are expected to speed themselves while eating off their companion stars, so the sparkly spheres' luminescence should decrease gradually as they finish their dinner. Darkness isn't anticipated to happen all at once, as it did with TW Pictoris.

"The brightness variations seen in accreting white dwarfs are generally relatively small, occurring on timescales of days to months," Scaringi said. That's why, he added, TW Pictoris' white dwarf turning off is "totally unexpected from our understanding of how these systems are supposed to feed through the accretion disc."

In solving the puzzle, the team found that during its "off" period, white dwarf's accretion disc was spinning so fast that it created a centrifugal force that prevented the disc' s matter from ever reaching the central star. Deshalb, the star's light was limited because it didn't have anything to eat on the expiring star. According to the study, such regulation is called magnetic gating.

The phenomenon is comparable to what happens when you ride a roller coaster and enter oblivion. Due to the force that forces the passengers into their seats, a rider wouldn't be in the loop.

After the "off" and "on" phases, the disc's speed of rotation returned to normal. Matter may once again escape the whirlwind for the white dwarf to nibble on.

"This is a new phenomenon," Scaringi added, adding that "because we can draw comparisons with similar behavior in much smaller neutron stars, it may be an important step in helping us to better understand the process of how other accreting objects feed on the material that surrounds them, and the important role of magnetic fields in this process."

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