Tau.Neutrino said:
Necroplanetology: The Strangest Field of Astronomy You’ve Never Heard Of
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.
more…
Oh, I see. There’s also something similar that’s been done with ordinary stars.
Stars have been known to swallow planets, particularly red giant stars that have grown to the point where they swallow the planets that orbit them.
But this is the first time I’ve heard of it with a white dwarf. A white dwarf is the wrong diameter to swallow planets, too small.
White dwarfs have a huge variation in atmospheres. Hydrogen, helium, carbon, elements heavier than carbon, all have been found as the dominant components of white dwarf atmospheres. It doesn’t have to come from swallowing a rocky planet, it’s more likely to come from the way that the star ejected material in the pre-existing planetary nebula phase.