Published: Thu, December 05, 2019
Sci-tech | By Patricia Wade

Giant planet discovered orbiting dead white dwarf star for the first time

Giant planet discovered orbiting dead white dwarf star for the first time

And, surprisingly, the Neptune-sized planet is more than four times the diameter of the Earth-sized star it orbits. The discovery indicated that there might be more of these massive planets rotating dead stars.

The white dwarf that the sun becomes will probably emit enough high-energy photons to evaporate Jupiter, Saturn, Uranus and Neptune eventually, the researchers determined.

Professor of Public Understanding of Science at the University of Brighton, Hal Sosabowski, told LBC News the planet offers us a glimpse at the potential future of our own solar system. This is what scientists think they are seeing around WDJ0914+1914: the first evaporating planet orbiting a white dwarf. So if we compare the Sun, the Sun is 6,000 - nearly five times as hot. After a team of researchers led by the University of Warwick, United Kingdom, observed near 7000 white dwarf stars mapped out by the Sloan Digital Sky Survey, they found one that stuck out like a sore thumb. These follow-up observations confirmed the presence of hydrogen, oxygen and sulphur associated with the white dwarf.

"It was one of those chance discoveries", Gänsicke said in a European Southern Observatory (ESO) press release. At some point, these stars have exhausted the lighter elements that fueled their earlier existence, flared up into a bloated red giant, and burned down into carbon and oxygen rich cores not much larger than the Earth (but far more massive).

"At first, we thought that this was a binary star with an accretion disk formed from mass flowing between the two stars", Gaensicke said.

"At first, we thought that this was a binary star with an accretion disk formed from mass flowing between the two stars", Gänsicke explained. "However, our observations show that it is a single white dwarf with a disk around it roughly ten times the size of our Sun, made exclusively of hydrogen, oxygen, and sulfur". He stated, "It was crystal clear that there was something extremely exciting going on in the system because we detected emissions of hydrogen, oxygen, and sulfur immediately".

After realizing just how unusual the white dwarf really was, the team shifted their focus to figuring out what the heck could create such a system. Their detailed analysis of the disk's composition matched what astronomers would expect if the guts of an ice giant like Uranus and Neptune were vaporized into space.

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A member of the research team, Dr. Matthias Schreiber from the University of Valparaíso, demonstrated through a set of calculations that the 28,000 degrees Celsius hot white dwarf is slowly evaporating this hidden icy giant, bombarding it with high energy photons and pulling its lost mass into a gas disc around the star.

The star is gobbling down the planet's atmosphere at a rate of over 3,000 tons per second, which makes it something of a gourmand, too. Perhaps the answer lies in a new observation that represents the first evidence of a giant exoplanet around a white dwarf. By finding out the wonderful particulars within the spectra taken by ESO's X-shooter, the group found that these components had been in a disc of gas swirling into the white dwarf and never coming from the star itself.

That's an odd combination of gases for a white-dwarf system.

"This discovery is major progress because over the past two decades we had growing evidence that planetary systems survive into the white dwarf stage", said Gänsicke. We've seen a lot of asteroids, comets and other small planetary objects hitting white dwarfs. "Having evidence for an actual planet that itself was scattered in is an important step".

The white dwarf was once a star similar to the sun but eventually ran out of fuel and swelled up into a red giant, a few hundred times the size of the sun. The Sun will burn all its hydrogen reserves in about 4.5 billion years. In the case of the Solar System, this will include Mercury, Venus, and even Earth, which will all be consumed by the red-giant Sun in about 5 billion years.

The revelation is the first of its kind as, before now, no other planet had been found to have lived through a star's transition to a white dwarf.

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