In 2015, astronomers found something weird. It was a white dwarf star, 570 light-years from Earth, with a peculiar dimming pattern. It dimmed several times to varying depths, each depth repeating on a 4.5 to 5-hour timeframe; and its atmosphere was polluted with elements usually found in rocky exoplanets.
Necroplanetology: The Strangest Field of Astronomy You’ve Never Heard Of (sciencealert.com)