Amateur astronomers help confirm extrasolar planet

Amateur astronomers help confirm extrasolar planet
Rice planet seekers aid in confirmation of Jupiter-like gas giant

Rice University astronomers searching for undiscovered planets around distant stars have helped confirm the work of an industrious group of amateur astronomers who are paving the way for more part-time star-watchers to join the global hunt for new planets.

In newly announced research slated to appear in an upcoming issue of The Astrophysical Journal, an international team of amateurs and professionals led by astronomer Peter McCullough of the Space Telescope Science Institute in Baltimore, discovered a Jupiter-like planet circling the star XO-1 about 600 light years from earth.

McCullough, who’s conducting a survey for extrasolar planets using a small set of self-constructed instruments atop a Hawaiian volcano, found the first signs of the new planet, dubbed XO-1b. He asked four amateur astronomers to make regular observations of the star, and their observations confirmed the planet’s existence.

McCullough also asked Rice astrophysicist Christopher Johns-Krull to monitor XO-1 using the Harlan J. Smith telescope at the University of Texas’ McDonald Observatory in far West Texas. Johns-Krull provided further confirmation of the planet and also determined that the star was very similar to the Sun. For example, XO-1 rotates slowly, which is important because the light from rapidly rotating stars can sometimes fool astronomers into thinking a planet exists when it does not.

“It would be very difficult for amateur astronomers to find objects like XO-1b on their own, but the amateurs are a great help to professionals because they can respond very quickly to potential new targets,” Johns-Krull said. “Since most professional observatories are booked far in advance, there would typically be a long wait to verify something like this.”

McCullough said the use of more modest telescopes could speed up the search for planets outside the solar system.

“This discovery suggests that a fleet of modest telescopes and the help of amateur astronomers can detect transiting extrasolar planets many times faster than we are currently spotting them,” McCullough said.

McCullough deployed a relatively inexpensive telescope made from commercial equipment to search for extrasolar planets. The telescope consists of two 200-millimeter telephoto camera lenses. The telescope, which looks like a pair of binoculars, is on the summit of the Haleakala volcano, in Hawaii.

McCullough’s team found the planet by noticing slight dips in the star’s light when the planet passed in front of the star. Although more than 180 extrasolar planets have been detected, XO-1b is only the tenth planet discovered using the so-called transit method. The observations revealed that XO-1b is in a tight, four-day orbit around its parent star.

The observations by Johns-Krull and Ph.D. student Marcos Huerta allowed the group to calculate the planet’s mass at about 0.9 the mass of Jupiter.

Johns-Krull and Huerta were able to help out McCullough’s group because they are conducting their own search for extrasolar planets. Specifically, Rice’s group is attempting to answer some fundamental questions about how planets form and how soon they form by looking for planets around very young stars.