This giant, Jupiter-like planet orbits very young star

A team of astronomers has discovered a planet that is at least eight times larger than Jupiter, CI Tau b, orbiting 2 million-year-old about 450 light years from Earth star in constellation Taurus.

In contradiction to the long-standing idea that larger planets take longer to form, astronomers from Rice, Lowell Observatory, the University of Texas at Austin, NASA and Northern Arizona University announced the discovery of a giant planet in close orbit around a star so young that it still retains a disk of circumstellar gas and dust.

"For decades, conventional wisdom held that large Jupiter-mass planets take a minimum of 10 million years to form," said lead author Christopher Johns-Krull, adding "That's been called into question over the past decade and many new ideas have been offered, but the bottom line is that we need to identify a number of newly formed planets around young stars if we hope to fully understand planet formation."

CI Tau b orbits the star CI Tau once every nine days. The planet was found with the radial velocity method, a planet-hunting technique that relies upon slight variations in the velocity of a star to determine the gravitational pull exerted by nearby planets that are too faint to observe directly with a telescope. The discovery resulted from a survey begun in 2004 of 140 candidate stars in the star-forming region Taurus-Auriga.

"This result is unique because it demonstrates that a giant planet can form so rapidly that the remnant gas and dust from which the young star formed, surrounding the system in a Frisbee-like disk, is still present," said co-leader Lisa Prato. "Giant planet formation in the inner part of this disk, where CI Tau b is located, will have a profound impact on the region where smaller terrestrial planets are also potentially forming."

The study will be published in the Astrophysical Journal.