Since it launched a year ago, the Interstellar Boundary Explorer (IBEX) has been monitoring heliosphere and how our Sun interacts with and the local interstellar medium — the gas and dust trapped in the vacuum of space. The first results from the mission, combined with data from the Cassini mission, are showing the heliosphere to be different from what researchers have previously thought. Data show an unexpected bright band or ribbon of surprisingly high-energy emissions. “We knew there would be energetic neutral atoms coming in from the very edge of the heliosphere, and our theories said there would be small variations in their emissions,” said David McComas, IBEX Principal Investigator at a press conference on Thursday. “But instead we are seeing two-to-three hundred percent variations, and this is not entirely understood. Whatever we thought about this before is definitely not right.”
The energies IBEX has observed range from 0.2 to 6.0 kiloelectron volts, and the scientists said its flux is two to three times greater than the ENA activity throughout the rest of the heliosphere. McComas and his colleagues said that no existing model can explain all the dominant features of this “ribbon.” Instead, they suggest that these new findings will prompt a change in our understanding of the heliosphere and the processes that shape it.
The solar wind streaks away from the sun in all directions at over a millions kilometers per hour. It creates a bubble in space around our solar system.
For the first ten billion kilometers of its radius, the solar wind travels at over a million kilometers per hour. It slows as it begins to collide with the interstellar medium, and the point where the solar wind slows down is the termination shock; the point where the interstellar medium and solar wind pressures balance is called the heliopause; the point where the interstellar medium, traveling in the opposite direction, slows down as it collides with the heliosphere is the bow shock.
McComas said his first reaction when the data started coming in was that of terror because he thought something must be wrong with the spacecraft. But as more data kept coming back each week, the team realized that they were wrong, and the spacecraft was right.
“Our next steps will be to go through all the detailed observations and rack them up against the various models and go find what it is that we are missing, what we’ve been leaving out,” he said.
For more information and visuals, see this NASA webpage.