The Catholic University of America

Feb. 23, 2010

CUA Physicist Awarded $364,000 to Crack One of Sun’s Riddles

  An artist’s conception of NASA’s Solar Probe Plus observing the sun. (Photo courtesy of NASA.)

It’s been a scientific mystery for decades: Why is the sun’s surface a relatively cool 6,000 degrees Kelvin, while the sun’s corona, or atmosphere, is an incredible 1 million degrees Kelvin? To enable CUA research professor of physics Leon Ofman to develop a scientific model to explain this phenomenon, NASA has this month awarded him a $364,000 four-year grant.

The huge increase in heat, Ofman believes, is caused by the movements of magnetic waves in the sun’s magnetic field, which generates friction and superheats the atomic particles within the corona.

The grant will enable Ofman to use NASA supercomputers to determine the equations of motion of millions of charged particles in the magnetized solar wind. He will use the results of the calculations to better understand the dynamics and interactions between the particles, and how energy is transferred between the magnetic fields and the particles, leading to the heating and acceleration of the solar wind.

This research, which he’ll be doing in tandem with NASA scientist Adolpho Viñas, has some practical implications. One implication concerns NASA’s plan to launch its Solar Probe Plus spacecraft in 2018 in order to make scientific measurements. The probe will approach seven times closer to the sun than any earlier spacecraft — to a point only 8.5 solar radii from the sun’s surface.

Ofman’s research will help NASA predict what conditions and temperatures to expect in the sun’s corona, which will help the space agency select and design the spacecraft’s instruments.

“To put it in layman’s terms, if you expect to find gas heated to 1 million degrees, you want to put a `thermometer’ in the spacecraft that can measure 1 million degrees or hotter,” he says. “If you put in a thermometer that measures only to a half-million degrees, you’re not going to be able to measure the temperature.

“That’s why you need to have an idea what to expect in the sun’s corona in order to properly design the instruments on board the Solar Probe Plus and protect it from the extreme environment— and that understanding is based on theoretical models.”

The CUA professor’s research will help NASA design the Solar Probe, but the probe’s findings will, in turn, indicate the degree of veracity of Ofman’s and other competing theories explaining why the solar atmosphere is so much hotter than the sun’s surface.

Ofman’s research has some more-earthly implications, too, since it could help scientists understand and predict the solar storms that sometimes disrupt communications satellites, harm astronauts, and, in extreme cases, knock out electrical power grids on Earth’s surface.

Ofman is part of CUA’s Institute of Astrophysics and Computational Sciences, whose member scientists carry out their research at NASA’s Goddard Space Flight in Greenbelt, Md.

MEDIA: For more information, contact Katie Lee or Mary McCarthy in the Office of Public Affairs at 202-319-5600.