14 large space rocks found beyond Neptune
By ANITuesday, September 14, 2010
WASHINGTON - A team of astronomers have found a cache of 14 large space rocks beyond the orbit of Neptune while sifting through archival observations from the Hubble Space Telescope.
Icy rocks like the newfound objects are known as trans-Neptunian objects (TNOs) because they typically reside outside Neptune’s orbit.
These objects include the former planet Pluto, now classified as a dwarf planet, as well as comets like the famed Halley’s comet.
Most TNOs are small and receive little sunlight, making them faint and difficult to spot.
Now, astronomers using clever techniques to cull the data archives of NASA’s Hubble Space Telescope have added 14 new TNOs to the catalog. Their method promises to turn up hundreds more.
“Trans-Neptunian objects interest us because they are building blocks left over from the formation of the solar system,” said lead author Cesar Fuentes, formerly with the Harvard-Smithsonian Center for Astrophysics and now at Northern Arizona University.
As TNOs slowly orbit the Sun, they move against the starry background, appearing as streaks of light in time exposure photographs.
The team developed software to analyze hundreds of Hubble images hunting for such streaks. After promising candidates were flagged, the images were visually examined to confirm or refute each discovery.
Most TNOs are located near the ecliptic-a line in the sky marking the plane of the solar system (since the solar system formed from a disk of material). Therefore, the team searched within 5 degrees of the ecliptic to increase their chance of success.
They found 14 objects, including one binary (two TNOs orbiting each other like a miniature Pluto-Charon system). All were very faint, with most measuring magnitude 25-27 (more than 100 million times fainter than objects visible to the unaided eye).
By measuring their motion across the sky, astronomers calculated an orbit and distance for each object.
Combining the distance and brightness (plus an assumed albedo, or reflectivity), they then estimated the size. The newfound TNOs range from 25 to 60 miles (40 to 100 km) across.
This research has been accepted for publication in The Astrophysical Journal and is available online. (ANI)
