Twist in the heavens
Thursday, Jan. 8, 2004
Associated Press
Atlanta — Stars usually heat up their family of planets, but in an amazing reversal, a Canadian astronomer has found a planet that is actually heating up its sun.
Astronomers from the University of British Columbia in Vancouver have reported that their study of a large planet orbiting a star 90 light-years away shows the magnetic field of the planet is producing hot spots on its parent sun, a reversal of the effect the sun has on planets such as Earth.
The planet is one of 119 known extra-solar planets, objects that orbit stars other than the sun. The star, called HD179949, is very like the sun. The planet is a gas giant 270 times larger than Earth, almost as big as Jupiter, the largest planet in our solar system. It circles very close to its parent star, completing one orbit every 3.09 days and moving at 563,000 kilometres an hour.
Evgenya Shkolnik of UBC reported at a meeting of the American Astronomical Society she and other astronomers have discovered as the planet orbits its star, it causes a hot spot within the outer gaseous layer.
“The hotspot moves across the surface of the star keeping pace with the planet, but just a little bit ahead,” Ms. Shkolnik said.
She said measurements of more than 100 orbits showed the hot spot on the face of the star exactly matches the motion of the planet.
Ms. Shkolnik said the hot spot is caused by the planet's powerful magnetic field, which transfers energy to hot gases just above the star's shining photosphere. The energy creates visible bright patches that can be detected by telescope instruments analyzing some types of ultraviolet light.
“This is the first time we have detected a magnetic field outside of the solar system,” she said.
Earth has a powerful magnetic field that helps protect the planet from particles streaming from the sun. The magnetic field is created by the motion of liquid iron and nickel surrounding the Earth's core.
Ms. Shkolnik said the magnetic field of the extrasolar planet suggests it too has a core structure that produces an energy force.
Magnetic energy from the extrasolar planet adds about 400 degrees to the 7,760C of the star's outer gaseous layer, Ms. Shkolnik said. The planet is about 1,500 degrees.
