NASA - National Aeronautics and Space Administration

A detailed image from NASA's Hubble Space Telescope offers the strongest evidence yet that an unruly and unseen planet may be gravitationally tugging on a dusty ring around the nearby star Fomalhaut (HD 216956).

Image to right: Dr. Mark Clampin, of the Goddard Space Flight Center, outside an observatory. Credit: Dr. Mark Clampin

The most detailed visible light image ever taken of a narrow, dusty ring unequivocally shows the center is a whopping 1.4 billion miles away from the star; a distance nearly halfway across our solar system. The most plausible explanation is an unseen planet, moving in an elliptical orbit, is reshaping the ring with its gravitational pull. The geometrically striking ring, tilted toward Earth, would not have such a great offset if it were only being influenced by Fomalhaut's gravity.

Dr. Mark Clampin of the Goddard Space Flight Center played a major role in this project as a Co-Investigator on the program. He is also a Co-Investigator of the Advanced Camera for Surveys' (ACS) Science Team and played a major role in the development of the instrument as Detector Scientist.

"Our new images confirm those earlier hypotheses that proposed a planet was perturbing the ring," said astronomer Paul Kalas of the University of California at Berkeley. The ring is similar to our solar system's Kuiper Belt, a vast reservoir of icy material left over from the formation of our solar system planets."

The ring's inner edge is sharper than its outer edge, a telltale sign that an object is gravitationally sweeping out material like a plow clearing away snow. Another classic signature of a planet's influence is the ring's relatively narrow width, about 2.3 billion miles. Without an object to gravitationally keep the ring material intact, the particles would spread out much wider.

Kalas and his collaborators, which included Clampin, used Hubble over a five-month period in 2004 to map the ring's structure. They used the ACS coronagraph to block out light from the bright star, so they could see details in the faint ring. One side of the faint ring has yet to be imaged, because it extended beyond the ACS field of view. Astronomers plan to map the entire ring later this summer.

For information about the research on the Web, visit: http://hubblesite.org/news/2005/10

Susan Hendrix
Goddard Space Flight Center