Jupiter-sized planet found orbiting distant white dwarf star

Astronomers have discovered a Jupiter-sized planet orbiting a distant white dwarf star, which is incredibly still intact. 

The planet, christened 'WD 1856 b' is located about 80 light years away in the northern constellation Draco.  

White dwarfs are the incredibly dense remains of sun-sized stars after they exhaust their nuclear fuel, shrunk down to roughly the size of Earth. 

WD 1856 b looms over its tiny star, which it circles every 34 hours thanks to an incredibly close orbit. 

The planet is roughly 20 times closer to the white dwarf than Mercury is to the Sun. 

Usually, as a star is dying, it engulfs its surrounding planets, meaning WD 1856 b is unique for somehow avoiding destruction. 

This discovery shows that it is possible for Jupiter-sized planets to survive their star's demise and settle into close orbits around the remaining embers.

Comparison between the inner Solar System and a white-dwarf system. The planet is roughly 20 times closer to the white dwarf than is Mercury to the Sun. The white dwarf was previously a giant star, the outer envelope of which once extended well beyond the planet’s orbit. This raises the question of how the planet arrived in its current orbit. All distances are in astronomical units (au), and the size of the giant star is shown to scale. The sizes of the other stars and planets are not shown to scale. (b) The relative sizes of the Sun and Earth, and of WD 1856+534 and its orbiting planet, are shown here for comparison

Comparison between the inner Solar System and a white-dwarf system. The planet is roughly 20 times closer to the white dwarf than is Mercury to the Sun. The white dwarf was previously a giant star, the outer envelope of which once extended well beyond the planet’s orbit. This raises the question of how the planet arrived in its current orbit. All distances are in astronomical units (au), and the size of the giant star is shown to scale. The sizes of the other stars and planets are not shown to scale. (b) The relative sizes of the Sun and Earth, and of WD 1856+534 and its orbiting planet, are shown here for comparison

WHAT IS A WHITE DWARF? 

A white dwarf is the remains of a smaller star that has run out of nuclear fuel.

While large stars – those exceeding ten times the mass of our sun - suffer a spectacularly violent climax as a supernova explosion at the ends of their lives, smaller stars are spared such dramatic fates.

When stars like the sun come to the ends of their lives they exhaust their fuel, expand as red giants and later expel their outer layers into space.

The hot and very dense core of the former star - a white dwarf - is all that remains.

White dwarfs contain approximately the mass of the sun but have roughly the radius of Earth, meaning they are incredibly dense.

The gravity on the surface of a white dwarf is 350,000 times that of gravity on Earth.

They become so dense because their electrons are smashed together, creating what's caused 'degenerative matter'.

This means that a more massive white dwarf has a smaller radius than its less massive counterpart.

 

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'It’s a pleasant surprise,' said lead researcher Andrew Vanderburg at the University of Wisconsin-Madison in the US.

'We’ve never seen evidence before of a planet coming in so close to a white dwarf and surviving.'

Vanderburg led the international collaboration of astronomers who analysed the data gathered by multiple light-reading telescopes, including NASA’s space telescope TESS and two large ground-based telescopes in the Canary Islands. 

Researchers spotted a star whose brightness dimmed by half about every one-and-a-half days – a sign that something big was passing in front of it on a tight orbit. 

But it was hard to interpret the data because the glare from a nearby star was interfering with TESS's measurements. 

To overcome this, the astronomers supplemented the TESS data from higher-resolution ground-based telescopes, including three run by amateur astronomers. 

'Once the glare was under control, in one night, they got much nicer and much cleaner data than we got with a month of observations from space,' said Vanderburg. 

White dwarfs are so much smaller than normal stars like our Sun – roughly the size of Earth. 

Therefore, large planets passing in front of them block a lot of the star’s light, making detection by ground-based telescopes much simpler.

The data revealed that a planet

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