It reads somewhat like a scene out of the first “Star Wars” movie (“Chapter IV” for the technical fans): Astronomers have discovered “death star,” a star that is literally tearing apart one of its own planets. But unlike the fictitious “Death Star,” the small planet-sized starship/weapon used by the Galactic Empire to blow Princess Leia’s home world of Alderaan to smithereens in a matter of minutes, this planet killer is methodically consuming the rocky object in its gravitational thrall bit by bit.
The Associated Press reported October 21 that astronomers originally discovered the white dwarf anomaly in data provided by NASA’s Kepler telescope, then used ground-based observations to confirm that the finding was valid. The study’s lead author, Andrew Vanderburg of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts, said of the finding: “This is something no human has seen before.”
At first, according to ABC News, the strange data set appeared to show the white dwarf, a star located in the constellation Virgo about 570 light years away, with what seemed like a cometary tail. Closer study indicated that a rocky object approximately the size of the dwarf planet Ceres seemed to be in the process of being deconstructed, much of it being pulled into the white dwarf, itself an object in its own death throes. (White dwarf star’s are the collapsed remains of a once-expanded red giant, and the stage prior to becoming a cold and energy-less black dwarf.)
Scientists observed that there was dip in the brightness of the star every 4.5 to 5 hours and were able to estimate that the distance of the small planet from it’s parent star as about 520,000 miles. The data also showed a sloping pattern from the main transit, which caused a dimming of the white dwarf by as much as 40 percent. The sloping extension resembled a comet’s tail. Andrew Vanderburg said that combining the observations led to his “eureka moment.”
He noted in a statement: “The eureka moment of discovery came on the last night of observation with a sudden realization of what was going around the white dwarf. The shape and changing depth of the transit were undeniable signatures. We are for the first time witnessing a miniature ‘planet’ ripped apart by intense gravity, being vaporized by starlight and raining rocky material onto its star.”
The dwarf planet’s death will be an inordinately long process, so the white dwarf is actually a slow death star. Scientists estimate that it will take approximately a million years for the white dwarf star to completely pull all the material to itself. Then it will be just a “thin metal dusting” on the white dwarf’s surface.
NASA’s Kepler telescope was launched into orbit in March 2009. Its scientific objective is to, according to the mission website, “explore the structure and diversity of planetary systems.”