In the first, astronomers discovered a giant planet orbiting a dead star


A small white dwarf, WD 1856, is closely orbited by a massive planet.

NASA Goddard

About 80 light years from Earth is the white dwarf WD 1856, a dead star that entered its final stages of life about 6 billion years ago. This slow death is usually quite lonely. In the dying process, some stars will expand too much, becoming a giant “red giant”. Like betelgeuse, And orbiting any nearby planet. Eventually, they use all their fuel and fall back into the white dwarfs, destroying everything on their wake.

Not so for WD 1856. For the first time, astronomers have detected a giant planet about the size of Jupiter, orbiting a dead star. He dubbed it WD 1856 b and is a surprising discovery – it survived destruction and shows that dead stars can still host planets with the right conditions for life.

The study, published Wednesday in the journal Nature, used NASA’s planet-hunting TES satellite and a suite of ground-based telescopes to examine WD 1856 for potential exoplanets. TESS, which examines stars for small dips in glowing potential planets, first saw the star in July and August 2019. When Team WD looked at 1856, a drastic decrease in brightness was observed.

Astronomers have recently started to grapple with the idea that these dead stars can still host many planets. In December, researchers discovered A planet slowly being eaten by a white dwarf About 1,500 light years away. However, the detection was based on light being emitted by debris and a disk of gas around the star, which researchers suggest would have been snatched from a planet like Neptune.

The discovery published in Nature is different today because it directly detects the orbit of the planet in front of its host star, which was not previously achieved for a white dwarf.

Each time the Jupiter-shaped planet passes in front of WD 1856, as seen from Earth, the light from the star goes away by about half. The process is incredibly brief, however, because the planet completes a full orbit every 1.4 days. The white dwarf is about 40% larger than the Earth itself. As a result, the dip in brightness lasts only eight minutes and is about 20 times greater than that of our Sun from the planet Mercury.

“This system is quite strange,” said Simon Campbell, an astrophysicist at Monash University, Australia. “In this case the planet is larger than the host star by a factor of 7!”

Using data collected by ground-based telescopes, the team was also able to estimate how massive the planet is. Infrared data from Dearest Spitzer Space Telescope This suggests perhaps 14 times as mass as Jupiter.

But if it is so close to its star, how did WD 1856B survive the expansion phase? The team offered two possible explanations.

When its host star became a red giant, it disturbed the planets in its system, which their orbits would ask. Disordered cosmic dance may have helped move the body of a planet like WR 1856b towards the star from where it ever orbits. Because it is a white white dwarf, which gives a lot of time for the planets to close. Potentially, this may mean that there are other planets orbiting the white dwarf.

“Not impossible, I don’t think we know how likely it is, because when you mess up in classrooms get chaotic,” Campbell said. “This is where an observation like this is important.”

Less likely, researchers say, is the idea that the star was able to overcome some outer layers and survive during the expansion phase. However, they conclude our current theories on this process, most likely that it was not formed in this way.

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Future observations, the team writes, should be able to confirm whether WD 1856B is indeed a planet if it is a failed star known as the “brown dwarf”. They point Upcoming, but long overdue, James Webb telescope And the Gemini Observatory to better understand WD 1856b. And, of course, if there are planets, they may be able to host life.

“There are people who are now searching for planets around white dwarfs that could potentially be habitable,” Ian Crosfield said in a press release. “It would be a very strange system, and you would have to think about how the planets actually survived at that time.”

Of course, if we can wait a few billion years, the fate of our own solar system will give us front row seats for white dwarfs. When our Sun starts dying, it will change in shape that will extend beyond the orbit of Mars. this in true sense On Large scale. All four inner planets of the Solar System will remain entangled in expansion until WD 1856, it runs out of fuel and falls back into a cold, white dwarf. Will outer planets, such as Jupiter, Saturn, and Neptune be flown into the spacecraft? I’m sure we won’t be around to find out.