De was using ZTF to search for events called novae – when a dead, collapsed star (known as a white dwarf) cannibalizes hot gas from another nearby star. The flash of optical light (visible to the human eye) after the planet’s demise showed up in observations by the Caltech-led Zwicky Transient Facility (ZTF), an instrument based at Palomar Observatory in Southern California that looks for cosmic events that change in brightness rapidly, sometimes in a matter of hours. Recent observations show the star has returned to the size and brightness it was before merging with the planet.

The transfer of energy caused the star to temporarily increase in size and become a few hundred times brighter. Drag from the atmosphere slowed the planet down, shrinking its orbit and eventually sending it below the star’s visible surface, like a meteor burning up in Earth’s atmosphere. The star is at the beginning of the final phase of its life – its red giant phase, which can last more than 100,000 years.Īs the star expanded, its outer atmosphere eventually surrounded the planet. The planet was likely about the size of Jupiter, with an orbit even closer to its star than Mercury’s is to our Sun. Researchers discovered the event – formally called ZTF SLRN-2020 – using multiple ground-based observatories and NASA’s NEOWISE (Near-Earth Object Wide Field Infrared Survey Explorer) spacecraft, which is managed by the agency’s Jet Propulsion Laboratory.

What we see in the stars journal