IBEX measures the wake produced by the Solar System for the first time
NASA’s Interstellar Boundary Explorer has successfully mapped the wake produced by our Solar System as it moves through the local interstellar medium.
Launched in 2008, IBEX has already helped us map the boundary of the Sun’s influence where the solar wind streaming from the Sun’s surface is no longer strong enough to push out its own “bubble” against the interstellar medium. We’ve previously covered the fascinating, complex interaction between the charged particles from the Sun and ISM that takes place at the edge of the heliosphere.
As part of these investigations, IBEX has now managed to map the wake of our Solar System as we move through the ISM for the first time by combining three years of data to produce this map of the ENA density looking down the tail.
What are ENAs, I hear you ask? Well, put simply, they are your average atoms. The Sun throws out charged ions (Protons, as one helpful reader reminded me in the specific case of a Hydrogen atom stripped of electrons) in every direction. When these charged ions meet other charged ions from the interstellar medium, they gain an electron and become neutral. Charged particles are affected by magnetic fields but neutral atoms are not, meaning that their paths stop curving and they effectively travel in straight lines forever afterward.
IBEX measures ENA energetic intensity as they impact the detector after travelling from the interface between the heliosphere and the interstellar medium, producing the image above. A couple of things are important here: the image roughly corresponds with the velocity of the solar wind produced by the Sun – fast at the poles and slower close to the equator. But theres also a few degrees of rotation, apparently due to the interaction between the solar wind and the magnetic field of the galaxy as the particles leave the influence of the heliosphere (represented by the purple magnetic field lines in the principle image).
Astrophysicists dont know exactly how long the tail is, but assume that it vanishes as particles from the solar wind effectively dissipate and become part of the local interstellar medium.
NASA has a pretty sweet video explaining the process here.
Image Credit: NASA/IBEX