This exoplanet, the planet outside our solar system, is the size of Jupiter and is known as WD1515B.
These giant explanate zips around star fossils, about the size of Earth, in very close orbit every 34 hours. By comparison, Mercury is the closest planet to the Sun in our solar system and takes 90 days to complete one orbit around the Sun.
The white dwarf is the one that swells up to the Sun-like star red giant during star evolution. The red giants burn and expand by their hydrogen fuel, consuming any planet near their path. For example, when our sun turns red billions of years from now, it will probably be Mercury and Venus – and maybe Earth.
After the star loses its atmosphere, all that remains is a collapsed core – a white dwarf. It has been cooling for billions of years.
Finding an intact planet in a nearby orbit around a white dwarf raises questions about how it got there, and how it survived the evolution of the star in a white dwarf.
Researchers believe that the planet was far away from its host star and moved closer after the star evolved.
Their simulations suggest that when the star became a white dwarf, the planet was kicked closer.
This study suggests that larger planets can survive the violent evolution of a star and then come into orbit around it.
“We think this star died and became a white dwarf about six billion years ago – so long ago that the sun, earth and solar system were not yet formed,” said Ian Crossfield, associate and assistant professor of physics studies. And astronomy at the University of Kansas, via an email.
“Although the star is just fading (only one-ten-thousandth as bright as our sun), the planet is now in a stable orbit, so we should study and learn about it there for many years to come.”
Looking for a dead solar system
NASA’s Planet-Hunting Transiting Exoplanet Survey Satellite (TCS) mission began in 2018 and has been searching for exoplanets around nearby stars ever since. This white dwarf is an ancient one observed by TSS.
The researchers took note of the planet while searching for data collected by TSS.
Crossfield said, “TST finds a planet by looking at a star, and it turns out how bright the star is for weeks.” If a planet is orbiting a star, and if a planet is between you and a star. If passed, a little light from that star would be blocked. Then as the earth passes the star will shine again – we will call it the ‘transition’ of the ‘planets.’
While TESS data can reveal someone’s presence, it’s not always clear what that budget is, he said. It could be an obscure star that is passing through a planet instead.
To help confirm the planet’s discovery, Crossfield used NASA’s Spitzer Space Telescope before completing its mission in January. Spitzer was created to make infrared observations and see objects that would be invisible in visible light.
Infrared light helped scientists determine whether the object was a small star or a large planet. Stars emit infrared light, but planets are colder than stars, so they don’t.
“What our Spitzer data showed is basically no infrared light,” Crossfield said. Said Crossfield. “And the ths depth of this transport is the same between TESS data and our Spitzer datasets. It really puts the final nail in the coffin that this thing is almost a planet instead of a star.”
Observations adopted by some ground-based telescopes operated by amateur astronomers also helped confirm the discovery.
No more than 14 times the mass of the planet Jupiter, the researchers determined.
After discovering the planet, the researchers ran simulations to determine how it got closer to the Earth’s star. If the red giant lifts nearby planets in its path, it will destabilize the distant orbit of the Jupiter-sized planet, sending it into an elliptical orbit that will bring it closer to the white dwarf, but also move it farther.
Over time, this getaway dance slowed down, causing the planet to go into short, tight orbit for billions of years.
When our own sun becomes a red giant, is it possible for the earth to survive the evolution of these stars?
“In about five billion years our sun will become a white dwarf,” Crossfield said. “There are a lot of open questions about whether the planets can survive in the process of a star by becoming a large swelling of red, swallowing up some of the inner planets, and then shrinking down and remaining as white dwarfs again.
“Can the planets really survive that – or is that impossible? And so far, there have been no known planets around the white dwarf.”
While Earth is unlikely to survive, “Mars, the asteroid belt and all gas-giant planets are likely to survive and remain in altered orbits around the Sun’s remnants,” Steven Parsn said in an article with Nature Studies. Parsons, Ernest Rutherford Fellow in the Astronomy Group at the University of Sheffield, was not involved in the study.
Do habitable planets exist around the stars?
Given the size of this planet, it is a gas giant like Jupiter in our solar system.
“This particular planet is not a good candidate for habitation,” said Andrew Vanderberg, a leading study author in the Department of Astronomy at the University of Wisconsin in Madison and an assistant professor in the Department of Astronomy. “It’s so big that it must have a smiling atmosphere made of hydrogen and helium. So it’s not a good place for life, because we know it to live.”
Researchers expect this white dwarf to continue and “enjoy a long, peaceful retirement, as billions of years come.”
However, the discovery of a planet around a white dwarf raises questions about the unique habitable atmosphere that may be close to the light of a dying star. As the white dwarf cools, it releases light and heat, so the nearest planet may actually be in the habitable zone of the star or in the Goldilocks zone where the planet’s temperature is right to support liquid water – and potentially life – on the surface.
“This tells us that white dwarfs may have planets, which is something we didn’t know before,” Crossfield said. “There are people who are now looking to move planets around a white dwarf that are potentially habitable. Now we at least know that some types of planets can survive and be found there, so it’s also more supportive to continue the search and More interest. Small planets around this white dwarf. “
It suggests that dead solar systems could actually host hospitable territories, Wonderberg said.
Researchers are looking forward to discovering smaller planets around the white dwarf in the future, as well as deciding more about the planet they found.
“It looks like if the white eclipse system could be a very good place to live, if your planet is in the right part of the system,” Wonderberg said. “So if WD 1856 could find a place in this part of the system, maybe other smaller planets, too. That includes rocky planets, in which we expect the best places for life to survive. “
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