Guest_Jim_* Posted October 23, 2015 Posted October 23, 2015 White dwarfs are an interesting kind of object, in part because the Sun will most likely turn into one in billions of years. They are also interesting because they can defy our expectations and show signs of materials they should not have. New observations by NASA's Kepler K2 mission and several ground facilities may have solved the mystery of polluted white dwarfs, according to researchers at the Harvard-Smithsonian Center for Astrophysics. When a star like the Sun grows old, it swells in size as its core tries to keep its nuclear fusion furnace going. Eventually though the outer layers of gas fall away, leaving the solid core to radiate its heat into space. These cooling cores are what we call white dwarfs and because of how they form, we expect to find them rich in carbon and oxygen, with some hydrogen and helium in their shells. Sometimes though we detect heavier elements, like silicon and iron, in their spectra, which is problematic because these elements should sink into the dwarf. Theories to explain this phenomenon suggest the dwarfs have been 'polluted' by rocky bodies, such as planets and asteroids that they have consumed. What has been discovered recently is a polluted white dwarf that still has a rocky planet orbiting it, and being destroyed by the dying star's heat and gravity, resulting in a metal debris cloud. The origin of the rocky object is still unknown, but the most likely explanation is that it was a planet that got its orbit shifted inward at some point. Source: Harvard-Smithsonian Center for Astrophysics Back to original news post Share this post Link to post Share on other sites More sharing options...
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