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Caught In The Act: Aging Star Devours Planet


Star Wars fans may be more familiar with Death Star, a moon-sized space station and super weapon that is capable of destroying a planet with a single destructive energy beam. Being a fictional concept, it can be easily brushed aside. But sometimes reality is stranger and more surprising than fiction. Using the giant Hobby-Eberly Telescope, an international team of astronomers has discovered the first evidence of a planet's destruction by its aging star.

The evidence indicates that the missing planet was devoured by its star, named BD+48 740, when it began expanding into a "red giant" phase, which represents an earlier stage in the star's destruction, or the stellar equivalent of advanced age. Every star in our galaxy is said to have at least one planet orbiting it.

A similar fate may await the inner planets in our solar system, when the Sun, the solar system's only star, becomes a red giant and expands all the way out to Earth's orbit some five-billion years from now, said Alexander Wolszczan, an Evan Pugh Professor of Astronomy and Astrophysics at Penn State and the discoverer of the first planet ever found outside our solar system.

The red-giant star - BD+48 740, which is older than the Sun with a radius about eleven times bigger, is found to be overabundant with lithium, which the astronomers attribute to the ingestion of a planet in the system originally in a closer orbit by the star.

The star's surviving planet is also found to have a highly unusual elliptical orbit - revolving around the star in an orbit only slightly wider than that of Mars at its narrowest point, but is much more extended at its farthest point.

According to the astronomers, the dive of the missing planet toward the star before it became a giant could have given the surviving massive planet a burst of energy, throwing it into a highly elliptical orbit, uncommon in planetary systems.

Summing up the evidence for the planet's destruction by its star, Eva Villaver of the Universidad Autonoma de Madrid in Spain said, "The highly elongated orbit of the massive planet we discovered around this lithium-polluted red-giant star is exactly the kind of evidence that would point to the star's recent destruction of its now-missing planet".

The discovery is posted in an early online edition of the Astrophysical Journal Letters.

by RTTNews Staff Writer

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