Strange new planet baffles astronomers

70652986 — Mon, 26 Mar 2007 06:28:15 -0400

Using a network of small automated telescopes known as HAT, Smithsonian astronomers have discovered a planet unlike any other known world. This new planet, designated HAT-P-1, orbits one member of a pair of distant stars 450 light-years away in the constellation Lacerta.

"We could be looking at an entirely new class of planets," said Gaspar Bakos, a Hubble fellow at the Harvard-Smithsonian Center for Astrophysics (CfA). Bakos designed and built the HAT network and is lead author of a paper submitted to the Astrophysical Journal describing the discovery. That paper is available online at http://arxiv.org/abs/astro-ph/0609369.

With a radius about 1.38 times Jupiter's, HAT-P-1 is the largest known planet. In spite of its huge size, its mass is only half that of Jupiter.

"This planet is about one-quarter the density of water," Bakos said. "In other words, it's lighter than a giant ball of cork! Just like Saturn, it would float in a bathtub if you could find a tub big enough to hold it, but it would float almost three times higher."

HAT-P-1 revolves around its host star every 4.5 days in an orbit one-twentieth of the distance from Earth to the Sun. Once each orbit, it passes in front of its parent star, causing the star to appear fainter by about 1.5 percent for more than two hours, after which the star returns to its previous brightness.

HAT-P-1's parent star is one member of a double-star system called ADS 16402 and is visible in binoculars. The two stars are separated by about 1500 times the Earth-Sun distance. The stars are similar to the Sun but slightly younger - about 3.6 billion years old compared to the Sun's age of 4.5 billion years.

Major funding for HATnet was provided by NASA.

Atmosphere detected on distant world orbiting another star

70652986 — Mon, 26 Mar 2007 05:16:28 -0400

One-hundred-and-fifty light years away from Earth, in the constellation Pegasus, is a star known as HD 209458. Using NASA's Hubble Space Telescope, a research team was able to detect the atmosphere of a planet orbiting the star. This marks the first time that scientists were able to observe the atmosphere of a planet outside our solar system. They also were able to get information about its chemical composition. The astronomers were not looking specifically for gases that would be found in a life-sustaining atmosphere, since it's not probable that a planet as hot as the one observed would contain life. But they think their technique can be used to look at other planets' atmospheres, which could provide the first direct evidence for life beyond Earth. The discovery was made by David Charbonneau of the California Institute of Technology and the Harvard-Smithsonian Center for Astrophysics, Timothy Brown of the National Center for Atmospheric Research, Robert Noyes of the Harvard-Smithsonian Center for Astrophysics, and Ronald Gilliland of the Space Telescope Science Institute.

all Robert Noyes stories

Strange new planet baffles astronomers

Atmosphere detected on distant world orbiting another star