Astronomers have announced the groundbreaking discovery of a massive, intact planet orbiting a much smaller white dwarf star—a first that promises to revolutionize exoplanet research.
As a Sun-like star ages, it expands into a red giant before shedding up to 80% of its mass, leaving behind a dense core known as a white dwarf. Our own Sun will follow this path in about 10 billion years.
Typically, nearby planets are engulfed and vaporized during this process. In our solar system, Mercury, Venus, Earth, and likely Mars will be consumed by the expanding Sun. This discovery challenges those expectations.
Using NASA's TESS satellite and Spitzer Space Telescope, researchers identified an intact planet orbiting perilously close to a white dwarf. Their findings are detailed in Nature.
Dubbed WD 1856 b, this Jupiter-sized planet orbits the white dwarf WD 1856+534—a star just 40% larger than Earth but seven times smaller than the planet. It completes an orbit every 34 hours, over 60 times faster than Mercury around our Sun. The system lies 80 light-years away in the Draco constellation.
How did this planet survive so close? "The white dwarf's formation usually destroys nearby planets, and intruders are torn apart by its gravity," explains Andrew Vanderburg of the University of Wisconsin-Madison. "Yet WD 1856 b remains intact."
Scientists believe it originated in an orbit at least 50 times farther out and migrated inward after the star became a white dwarf, possibly due to interactions with other planets. The exact mechanism remains under investigation.
In a companion Nature article, Steven Parsons of the University of Sheffield notes this opens "the tantalizing prospect of detecting additional worlds."
At just 82 light-years away, gravitational influences from unseen planets could be measurable from Earth, ushering in a new era of exoplanet studies.
