Dying star is blasting nearby planet to smithereens
NASA鈥檚 Kepler K2 mission has shed some light on what happens to nearby planets when a star dies. And no 鈥� this is not the synopsis for a Star Wars movie.
After a star burns through its nuclear fuel and dies, the shriveled stellar corpse, known as a white dwarf, collapses in on itself. The remaining core of the white dwarf emits such a strong gravitational pull, at least the strength of Earth鈥檚 gravity, that entire planets can be sucked in.聽
Andrew Vanderburg, a graduate student at the Harvard-Smithsonian Center for Astrophysics (CfA), was viewing such a white dwarf star when he saw a planet some 520,000 miles away from the dead star (twice the distance between the Earth and the moon) start to dip and flicker away. Mr. Vanderburg and his colleagues soon realized they were witnessing a dead star eat a planet.聽
鈥淭he white dwarf was ripping it apart by its extreme gravity and turning it into dust,鈥� .
鈥淭his is something no human has seen before,鈥� Vanderburg said Wednesday. 鈥淲e鈥檙e watching a solar system get destroyed.鈥�
And because the gravitational pull of a white dwarf is so strong, the star鈥檚 heavy elements like silicon and iron should be sucked deep into the dwarf鈥檚 core. But surprisingly, astronomers say they often see signs of these heavier elements in the white dwarf鈥檚 light spectrum.
鈥淚t鈥檚 like panning for gold 鈥� the heavy stuff sinks to the bottom. These metals should sink into the white dwarf鈥檚 interior where we can鈥檛 see them,鈥� CfA co-author John Johnson explains .
Astronomers have previously predicted that 鈥渨hite dwarfs showing of heavy metals became 鈥榩olluted鈥� when they consumed rocky planets,鈥� much like the consumption Vanderburg witnessed.
鈥淲e now have a linking white dwarf pollution to the destruction of rocky planets,鈥� says Vanderburg.
Researchers say Earth and Mars can expect the same grim fate, when our sun runs out of energy billions of years from now.
鈥淲ithin the next million years or so, all that will remain of these asteroidal bits is a thin metal dusting on top of an innocent-looking white dwarf star,鈥� says CfA鈥檚 statement. 鈥淭his discovery also confirms a long-standing theory behind the source of white dwarf 鈥榩ollution鈥� by metals.鈥�
