Since its Oct 2008 release, NASA's Interstellar Edge Traveler (IBEX) has provided pictures of the unseen communications between our home in the universe and interstellar space. Contaminants originating from this border produce a stunning, filter lace, which had yet to be described despite more than a number of possible concepts. In a new "retention model," scientists from the School of New Hampshire and South west Research Institution suggest that billed particles stuck in this area create the lace as they evade as fairly neutral atoms.
The Sun constantly delivers out a solar breeze of billed particles or ions traveling in all guidelines at supersonic rates of speed. IBEX cameras measure dynamic fairly neutral atoms (ENAs) that form when billed particles become neutralized.
As solar breeze ENAs keep the solar program, the majority move out in various guidelines, never to re-enter. However, some ENAs keep the solar program and impact other fairly neutral atoms, becoming expenses particles again. These new pick-up ions begin to gyrate around the local interstellar attractive area just outside the solar program. In the areas where the attractive area is verticle with respect to their initial movement, they spread rapidly and heap up. From those areas, some of those particles return to the solar program as additional ENAs -- ENAs that keep the solar program and become billed and then re-neutralized, only to travel back into the solar program as ENAs a second time.
"The syrup you pour on a pancake piles up before slowly oozing out to the sides," says Dr. David McComas, IBEX principal investigator and assistant vice president of the SwRI Space Science and Engineering Division. "The secondary ENAs coming into the solar system after having been temporarily trapped in a region just outside the solar system do the same thing. As they pile up and get trapped or retained, they produce higher fluxes of ENAs from this region and form the bright ribbon seen by IBEX."
ENA energies observed in the ribbon correlate to the speed of the solar wind, which is slower (around 1 million miles per hour) at low latitudes and faster (up to 2 million miles per hour) at high latitudes.
"This was the clue that made us think the ribbon was caused by a secondary ENA source, because it so directly reflects the latitudinal structure of the solar wind," says McComas.
Simulations using a realistic solar wind structure showed remarkably good association with the IBEX data, closely reproducing the observed ribbon structure, location, and latitudinal ordering by energy. Thus far, the retention model appears best able to reproduce the IBEX observations. However, more studies are needed to confirm if variations in the solar wind affect the ribbon, as theorized.
