August 21, 2012
Jupiter-like Planet Devoured By Its Own Star
Lee Rannals for redOrbit.com - Your Universe Online
Astronomers say they've witnessed the death of a planet, which found its journey ended by way of its own star.
The scientists reported in the Astrophysical Journal Letters that BD+48 740 became a red giant at the end of its life, helping it to eventually consume its close-by planet.
"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 5 billion years from now," team member Alex Wolszczan, a professor of astronomy and astrophysics at Penn State University, said.
The team first detected evidence of the planet's destruction while studying the aging star and looking for planets surrounding it.
They said that the evidence includes the star's peculiar chemical composition, as well as the unusual elliptical orbit of its surviving planet.
"Our detailed spectroscopic analysis reveals that this red-giant star, BD+48 740, contains an abnormally high amount of lithium, a rare element created primarily during the Big Bang 14 billion years ago," team member Monika Adamow said.
The researchers said that lithium is easily destroyed in stars, which is why abnormally high abundance in this older star is so unusual.
"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," Adamow said.
According to the findings, the missing planet could have given the remaining planet a gravitational push as it spiraled towards its destruction, helping to give the surviving planet its highly elliptical orbit.
"Catching a planet in the act of being devoured by a star is an almost improbable feat to accomplish because of the comparative swiftness of the process, but the occurrence of such a collision can be deduced from the way it affects the stellar chemistry," 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."