Chuck Bednar for redOrbit.com – @BednarChuck
In Star Wars, the Death Star was a massive spaceship capable of destroying a planet with just one shot of its laser, but a recently-discovered white dwarf star may have ripped apart a planet at its core by coming too close to it, making it a real-life Death Star.
It probably looked something like this…
Earlier this week, NASA reported that its Chandra X-ray Observatory along with several other telescopes had discovered evidence that the white dwarf may have been a planet-killer, with the dense core of a sun-like star that had run out of nuclear fuel once destroyed an entire world.
Findings the source of X-rays in the NHC 6388 cluster
Using the ESA’s INTErnational Gamma-Ray Astrophysics Laboratory (INTEGRAL), scientists found a new X-ray source near the center of the globular cluster NGC 6388. Observations had hinted that this cluster had an intermediate-mass black hole at its center, and the X-ray detection suggested that they were produced by hot gas swirling towards the black hole.
They conducted follow-up observations using Chandra and determined that the X-rays were not actually coming from a black hole at the center of NGC 6388, but instead from a region located somewhat off to the side. Since the central black hole was eliminated as a potential source of the X-rays, the hunt continued to find out what was actually causing them, and the team turned to the X-ray telescope on board NASA’s Swift Gamma Ray Burst mission for assistance.
During the course of those observations, the source became dimmer, and the rate at which the X-ray brightness decreased correlated with theoretical models of a disruption of a planet caused by the gravitational tidal forces of a white dwarf.
So, could a white dwarf actually destroy a planet?
Given that a white dwarf stars is usually only about the same size as the Earth, how could it have caused an entire planet to be destroyed? The answer is – no, not aliens – gravity. Once a star hits its white dwarf stage, its material becomes tightly packed in a radius just one-percent as big as it once was. As a result, its gravitational pull and other forces become far more powerful.
In the aforementioned theoretical models, a planet is first pulled away from its parent star by the gravity of the passing white dwarf, and when it gets too close, it can be ripped to shreds due to the intense tidal forces of the dense star remnant. The planetary debris is then heated and glows in X-rays as it falls onto the white dwarf, NASA explained, with the observed amount of X-rays emitted at different energies agreeing with expectations for a tidal disruption event.
In this case, the researchers estimate that the destroyed planet would have contained about a third of the mass of Earth, while the white dwarf had about 1.4 times the Sun’s mass. While it cannot be said for certain that this is what happened, the agency explained that the argument in favor of it was bolstered by the use of data from multiple telescopes to eliminate other possibilities.
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