Planetary Death Spiral

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For the first time, astronomers have caught a star in the act of engulfing its planet, an ill-fated encounter that will play out in our own solar system in 5 billion years. This artist’s animation shows the gas giant meeting its demise as it spiraled into its parent star. Ultimately, the planet plunged into the core of the star, which triggered the star to expand and brighten.

The aging star depicted here, called ZTF SLRN-2020, is roughly 10 billion years old. It had begun to inflate over a period of hundreds of thousands of years as it transformed into a red giant and, as a result, inched closer to its inner planet. As the planet came close to touching the surface of the star, the increasing frictional forces caused the planet to rapidly spiral inward. Eventually, on timescales that are not certain, the planet plunged into the core of the star. When that happened, the star inflated to four times its size and brightened by a factor of more than a hundred.

This discovery was made with a combination of telescopes, including the Zwicky Transient Facility (ZTF) at Caltech’s Palomar Observatory, the W.M. Keck Observatory, and NASA’s NEOWISE mission. ZTF SLRN-2020 lies 15,000 light-years away in the constellation Aquila.

Image credit: R. Hurt/K.Miller (Caltech/IPAC)