This planet just survived the death of its star

A giant gaseous planet orbiting a dead star provides a glimpse of the expected consequences of the disappearance of our Sun.

Astronomers have discovered the first confirmed planetary system that resembles the expected fate of our solar system, when the Sun reaches the end of its life in about five billion years.

The researchers detected the system using the WM Keck Observatory on Maunakea in Hawaiʻi; It consists of a Jupiter-like planet with a Jupiter-like orbit that revolves around a white dwarf star located near the center of our Milky Way.

"This test confirms that planets orbiting a sufficiently large distance can continue to exist after the death of their star"says Joshua Blackman, an astronomy postdoctoral researcher at the University of Tasmania (Australia) and lead author of the study.

"Since this system is an analog to our own solar system, it suggests that Jupiter and Saturn could survive the red giant phase of the Sun, when the Sun runs out of nuclear fuel and self-destructs."

The study is published in today's issue of the journal Nature.

"The future of the Earth may not be so rosy because it is much closer to the Sun," says co-author David Bennett, a senior research scientist at the University of Maryland and NASA's Goddard Space Flight Center.

"If humanity wanted to move to a moon of Jupiter or Saturn before the Sun fries the Earth during its red supergiant phase, we would continue to orbit the Sun, although we could not count on the Sun's heat as a white dwarf for long. time."

A white dwarf is what main sequence stars, like our Sun, become when they die. In the later stages of the stellar life cycle, a star burns all the hydrogen in its core and becomes a red giant star. Since these compact stellar corpses are small and no longer have the nuclear fuel necessary to radiate strongly, white dwarfs are very faint and difficult to detect.

High-resolution near-infrared images obtained with the Keck Observatory's laser guide star adaptive optics system , along with its Near Infrared Camera ( NIRC2 ), reveal that the newly discovered white dwarf has 60 percent of the mass of the Sun and that its surviving exoplanet is a giant gas world with 40 percent more mass than Jupiter.

The team discovered the planet using a technique called gravitational microlensing, which occurs when a star near Earth momentarily aligns itself with another farther away. This creates a phenomenon in which the gravity of the foreground star acts like a lens and magnifies the light from the background star. If there is a planet orbiting the nearest star, the magnified light is temporarily warped as the planet buzzes past.   

Strangely, when the team tried to search for the planet's host star, they unexpectedly discovered that the light from the star was not bright enough to be an ordinary main sequence star. The data also ruled out the possibility that a brown dwarf star was the host.

"We have also been able to rule out the possibility of a neutron star or a black hole as a host. This means that the planet orbits a dead star, a white dwarf ," says co-author Jean-Philippe Beaulieu, Warren Professor of the Chair. Astrophysicist at the University of Tasmania and director of CNRS research at the Paris Institute of Astrophysics. 

"It offers a vision of what our solar system will be like after the disappearance of the Earth, hit by the cataclysm of our Sun."

"It's wonderful to see today an example of the kind of science that Keck will do en masse when Roman begins his mission."

"It's wonderful to see today an example of the kind of science that Keck will do en masse when Roman begins his mission." 

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