UTAH STATE PROFESSOR AND STUDENT FEATURED IN “NATURE”
Utah State University chemistry professor David Farrelly and chemistry doctoral student Sergey Astakhov are bringing scientists around the world one step closer to understanding the solar system.
Together with mathematicians Steve Wiggins and Andy Burbanks, from Bristol University in England, they have provided a new explanation of how small bodies become moons by switching from orbiting the Sun to orbiting a planet.
The group‚s findings are featured in the May 15 edition of the journal “Nature” and focus on how chaos assists the process by which small, “irregular” moons were captured. The “irregular moons”now number 52 at Jupiter and 14 at Saturn.
Regular moons have a roughly circular orbit around a planet and are believed to have been formed beside a planet during the early history of the solar system; in contrast, irregular moons have an orbit that is highly elliptical and tilted and often orbit a planet in the opposite direction to the regular moons. These moons are believed to have originally encircled the Sun and to have been subsequently “captured% by the planet they now orbit.
“It is, perhaps, surprising that orderly structures in the solar system can arise from chaos,” said Farrelly. “When most people hear the word chaos, they think of something that is disorderly. But in fact, when it comes to the Solar System, we have found that chaos can eventually lead to order and predictability.”
Astronomers have long understood that when a moon approaches a planet, it must lose energy by experiencing friction to get permanently captured. The new finding is that moons get temporarily trapped in chaotic motion and have a hard time escaping from the gravitational grip of a planet that has captured the moon. This allows the moon the needed time to dissipate excess energy therefore becoming permanent fixtures orbiting the planet.
The joint Utah-Bristol team hopes that their model will help in understanding the beginning of the solar system and, in particular, how planets and moons were formed.
The researchers said it is unusual for a group of chemists and mathematicians to be working on a project in astronomy, but they note that the quantum theory grew out of an attempt to apply methods of celestial mechanics to atoms and molecules. Astakhov said the ultimate goal of their research boils down to understanding chemical reactions. “Moons are interesting to me because the way they were captured closely resembles what happens during certain chemical reactions,” he said. The research group used a supercomputer called a Beowulf cluster to perform the massive calculations required. The computer was built by Utah State undergraduate computer science and chemistry major Alex Birch and recent Utah State graduate Brian Retford. The work was supported by the U.S. National Science Foundation, the Royal Society (UK) and the United States Office of Naval Research.
Farrelly has been a professor of Chemistry and Biochemistry at Utah State for 12 years.
For more information on the research, contact Farrelly at (435) 797-1608 or (435) 757-2188 or email him at david@habanero.chem.usu.edu.