Dying Star Destroys Planet, First Time Astronomers Observe Phenomenon.
Astronomers at Penn State University have discovered the first evidence of a planet's destruction by a dying star. Astronomers discovered the planet was "missing" from its orbit around a red giant star. Stars enter the red giant phase in the final stages of their life.
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"A similar fate may await the inner planets in our solar system, when the Sun becomes a red giant and expands all the way out to Earth's orbit some five-billion years from now," said Alex Wolszczan, an Evan Pugh Professor of Astronomy and Astrophysics at Penn State, University, who is one of the members of the research team.
The astronomers realized a planet had disappeared when they observed another planet orbiting the red giant star, named BD 48 740. The planet, estimated to be larger than Jupiter, was observed having an extremely elliptical orbit. The path it travels around the star is unusual, and astronomers believe that it can only occur because the absence of the missing planet has impacted the others gravity.
"We discovered that this planet revolves around the star in an orbit that is only slightly wider than that of Mars at its narrowest point, but is much more extended at its farthest point," Andrzej Niedzielski, another astronomer on the team, said in a Penn State press release. "Such orbits are uncommon in planetary systems around evolved stars and, in fact, the BD 48 740 planet's orbit is the most elliptical one detected so far."
BD 48 740 also contains high levels of lithium, an incredibly rare substance to be found inside a star. Lithium, created during the Big Bang 14 billion years ago, is easily destroyed by stars and is rarely, if ever, present in a star's anatomy. The astronomers believe the presence of the element is an indication that the missing planet collided with the star.
"Theorists have identified only a few, very specific circumstances, other than the Big Bang, under which lithium can be created in stars," Wolszczan said in the release. "In the case of BD 48 740, it is probable that the lithium production was triggered by a mass the size of a planet that spiraled into the star and heated it up while the star was digesting it."
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