July 10, 2013
NASA’s IBEX Captures First Images Of Our Heliosphere’s Tail
[ Watch the Video: IBEX Provides First View of the Solar System’s Tail ]
Lee Rannals for redOrbit.com - Your Universe Online
NASA's Interstellar Boundary Explorer (IBEX) spacecraft has unveiled an unexpected structure in the first complete pictures of the solar system's heliotail. Scientists believe a "tail" trails the heliosphere, which is the giant bubble in which our solar system resides. As the heliosphere moves through interstellar space, it creates a tail similar to that of a comet.
The first IBEX images released in 2009 showed an unexpected ribbon of surprisingly high energetic neutral atom (ENA) emissions circling the upwind side of the solar system. One structure dominated by low energy ENAs emerged, which was first identified as the heliotail. However, as more data started coming in, researchers found a second tail region to the side of the previously identified one. Researchers writing in the Astrophysical Journal determined the structures better resemble "lobes" than a single unified tail.
"We chose the term 'lobes' very carefully," says Dr. Dave McComas, IBEX principal investigator and assistant vice president of the Space Science and Engineering Division at Southwest Research Institute. "It may well be that these are separate structures bent back toward the downwind direction. However, we can't say that for certain with the data we have today."
The scientists are using the nautical terms port and starboard to distinguish the lobes because they say the heliosphere is like a "vessel" transporting our solar system through the galaxy.
The heliotail is the area where the Sun's million mile per hour solar wind flows down and escapes the heliosphere. The solar wind heads down the tail in the port and starboard lobes, creating a heliotail that is much flatter and broader than scientists expected.
"Imagine sitting on a beach ball. The ball gets flattened by the external forces and its cross section is oval instead of circular. That's the effect the external magnetic field appears to be having on the heliotail," explained McComas.
The IBEX spacecraft uses two novel ENA cameras to image and map the heliosphere's interactions. This spacecraft has provided the first global views and new knowledge about our solar system's interaction with interstellar space.
"We often think we know what we're going to study in science, but the work sometimes takes us in unexpected directions," says McComas. "That was certainly the case with this study, which started by simply trying to better quantify the small structure incorrectly identified as an 'offset heliotail.' The heliotail we found was much bigger and very different from what we expected."
NASA's 35-year-old Voyager 1 is now exploring the edge of the heliosphere, and scientists believe that it could puncture through to find itself in interstellar space at any moment. Like IBEX, this spacecraft has helped provide valuable information about the bubble that surrounds our solar system.