October 30, 2009

University scientist’s maps follow solar wind past Pluto

U of C astronomer and astrophysicist Priscilla Frisch creates maps that are out of this world. The interstellar cartographer’s most recent findings, which were published in the latest issue of Science Magazine’s Express Science, chart the boundaries of our solar system with the help of a new satellite called the Interstellar Boundary Explorer (IBEX).

IBEX is a satellite funded by NASA that tracks atoms that bounce back from the edge of the heliosphere, which extends past Pluto. These maps are “the most distant images of our solar system that have ever been made,” Frisch said.

As the sun moves through our galaxy, its velocity creates a bullet-shaped wind pattern—the heliosphere. The million-degree solar winds move at a million miles per hour and create a magnetic field when they interact with interstellar gases. That field is the rebound point for the particles IBEX records.

Up until this point, two Voyager satellites were the only instruments that have attempted to study these far reaches of our solar system. But with only two reference points, little information can be obtained about the shape and make-up of the interstellar boundary. Moreover, these satellites were launched decades ago and still haven’t reached Pluto, while IBEX has already gathered information from twice as far away.

IBEX, unlike the Voyager satellites, remains in Earth’s orbit and can still collect information on the interstellar boundary. It does this by recording energetically neutral atoms, or ENAs. IBEX’s new technology allows it to track these difficult-to-detect particles and uses their velocity to estimate the edges of the heliosphere.

This breakthrough technology has also led to the discovery of a “ribbon of emission” of ENAs, Frisch said. This ribbon is something that both Voyager satellites missed on their journeys to the edge of the solar system.

IBEX can also interpret information from beyond the farthest reaches of the sun and into the interstellar gas. Ongoing research should reveal the number of oxygen atoms in space, “the cosmic abundance of oxygen,” Frisch said. These results will hopefully quell a recent debate in astrophysics over the density of oxygen in space.