Found evidence of a habitable-zone planet lurking in orbit around a white dwarf

(ORDO NEWS) — Researchers studying a white dwarf star report they have found signs of a possible planet orbiting the star’s habitable zone.

Often referred to as the Goldilocks zone, this orbit is characterized by temperatures that allow liquid water to exist on the planet’s surface, making it an ideal place to search for extraterrestrial life. If the discovery is confirmed, it would only be the second planet found around a white dwarf and the first found in the habitable zone.

White dwarf stars are more or less like our Sun, only they have exhausted their hydrogen fuel and are slowly cooling down, approaching their final death. This cooling phase can last up to two billion years, providing ample opportunities for the origin of life on any planet in the star’s habitable zone.

However, any planet that existed in the habitable zone prior to the star’s death would be destroyed during the red giant phase, as would Mercury, Venus, and most likely Earth when our Sun makes its death transition. This situation means that any planet that finds itself in a water-friendly orbit of a white dwarf would have to start life from scratch.

In the latest study, a team of astronomers studying the white dwarf say they have spotted signs of a planet that could meet that criteria, making it an enticing target for life-hunting astronomers.

To make their discovery, researchers at University College London pointed the New Technology Telescope (NTT), part of the La Silla Observatory in Chile, at a white dwarf about 117 light-years away known simply as WD1054-226.

Over the course of 18 nights, the research team recorded regular changes in the brightness of the star, which indicated the presence of a number of planetary structures the size of the Moon in its orbit.

“The lunar structures we observe are irregular and dusty (like comets, for example) rather than solid spherical bodies,” study lead author Jay Farihy, a professor of physics and astronomy at the University of California, said in a press release announcing the discovery. “Their absolute regularity – one pass in front of a star every 23 minutes – is a mystery that we currently cannot explain.”

However, the professor notes, the one explanation that makes the most sense is the planet.

“The exciting possibility is that these bodies are held in such an evenly spaced orbit by the gravitational influence of a nearby planet. Without this influence, friction and collision would cause the structures to separate, losing the exact regularity that is observed.”

“The possibility of a planet in the habitable zone is both exciting and unexpected,” Farihi said. “We weren’t looking for it.”

The professor warns that his team hasn’t found an exoplanet, but instead found strong evidence for its existence. This is mainly due to the fact that artificial telescopes cannot directly image an exoplanet, so their existence must be judged by the effect on the host star.

“It’s important to remember that more evidence is needed to confirm the presence of a planet,” Farihi explained. “We can’t directly observe the planet, so confirmation could come from comparing computer models with further observations of the star and orbital debris.”

In the case of WD1054-226, the team took the extra step of comparing their observations with similar observations made by NASA’s Transiting Exoplanet Survey Satellite (TESS). This comparison confirmed the presence of planetary structures.

The discovery, published in the Monthly Notices of the Royal Astronomical Society, adds to a growing body of evidence supporting the idea that life can exist not only on planets orbiting stars like our Sun, but also in space around extremely common white stars. dwarf stars.

Since 95% of stars like the Sun turn into white dwarfs over time, this discovery greatly expands the number of places astronomers can look for alien life. Let the hunt for extraterrestrial life begin!

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