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New Discovery May Offer Preview of Solar System’s Demise

UMD Astronomers Among Team That Found Jupiter-like Planet Survives in Orbit Around Dead Star

By Maryland Today Staff

White dwarf

A Jupiter-like planet orbits a dead star in an artist's conception of a system discovered by a research team including UMD astronomers. Our solar system could take on a similar form five billion years from now, when the sun has run out of nuclear fuel and Earth and the other inner planets will likely have been destroyed in its transition to a white dwarf.

Astronomers have discovered the first confirmed planetary system that offers a glimpse into the fate of our solar system about five billion years into the future, when our sun is expected to exhaust its nuclear fuel.

The newly discovered planetary system consists of a Jupiter-like planet revolving in an orbit similar to that of the gas giant around a white dwarf, or dead star, located near the center of the Milky Way galaxy. This discovery, announced in a study published today in the journal Nature, provides evidence that planets orbiting far enough from their sun can continue to exist after the star dies.

“It is the first known planet orbiting a white dwarf in a Jupiter-like orbit,” said study co-author David Bennett, a University of Maryland astronomer and researcher at NASA’s Goddard Space Flight Center. “Earth’s future may not be so rosy because it is much closer to the sun.”

Most scientific evidence suggests that planets in closer orbits are consumed or destroyed by the white dwarf they orbit. Simulations predict that larger planets in more distant orbits around stars like our sun can survive their sun’s demise, but until now, there was no evidence.

“Given that this system is an analog to our own solar system, it tells us Jupiter and Saturn could potentially survive the sun’s red giant phase, when it runs out of nuclear fuel and self-destructs,” said Joshua Blackman, an astronomy postdoctoral researcher at the University of Tasmania in Australia and lead author of the study.

When a star like our sun runs out of fuel, the hydrogen remaining in its core burns off and it balloons into a red giant before collapsing into a white dwarf. At that point, all that is left is a hot, dense core, typically Earth-sized and half as massive as the sun.

Because these compact stellar corpses are small and no longer have the nuclear fuel to radiate brightly, white dwarfs are very faint and difficult to detect. The researchers found the system using the W. M. Keck Observatory on Maunakea in Hawaii.

The team detected the planet using a technique called gravitational microlensing, which occurs when a star close to Earth momentarily aligns with a more distant star, and gravity from the foreground star acts like a lens and magnifies the light from the background star. But if there is a planet orbiting the closer star, it temporarily warps the magnified light as the planet whizzes by.

NASA’s upcoming mission, the Nancy Grace Roman Telescope (formerly known as WFIRST), will conduct a much more sensitive exoplanet microlensing survey that will further this investigation. Roman, expected to launch by early 2027, will be capable of a much more complete survey of planets orbiting white dwarfs toward the center of the Milky Way. This will allow astronomers to determine how common it is for Jupiter-like planets to survive their star’s final days or if a significant fraction of them are destroyed by the time their host stars become white dwarfs.

This story was adapted from text provided by NASA’s Goddard Space Flight Center.

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