Map directions

Scientists use data from the IBEX satellite to create the first map of the sun’s heliosphere

In a monumental example of NASA’s ongoing solar mapping efforts, the edge of the sun’s mysterious heliosphere has finally been mapped in 3D for the very first time, providing a wealth of new information about how solar and interstellar winds intersect and interact.

Astronomers accomplished this groundbreaking feat by using data derived from NASA’s Interstellar Boundary Explorer (IBEX) spacecraft to determine the boundaries of our star’s heliosphere, that bubble of charged particles surrounding the sun.

The information image below depicts that vast region of space enveloping the solar system that is rich in solar winds and forms the boundary between the heliosphere (in brown) and interstellar space (in dark blue).

To accomplish this task, NASA’s Earth-orbiting IBEX satellite detects particles emerging from the sun’s heliosheath, which can then be recorded and labeled. Directed by Dr. Dan Reisenfeld of Los Alamos National Laboratorythis endeavor forced Reisenfeld and his colleagues to dissect IBEX data to map the edges of this cosmic zone known as the heliopause.

At this point, the solar winds make their way to interstellar space where they collide with the interstellar wind, which has entirely different dynamics and is actually pushing towards the Sun. The researchers were able to quantify these measurements by exploiting sonar-like echolocation properties used by bats.

“Just as bats send out sonar pings in all directions and use the return signal to create a mental map of their surroundings, we used the Sun’s solar wind, which goes in all directions, to create a map. of the heliosphere,” Dr. Reisenfeld explained in an official statement. Los Alamos press release.

This study was published in the June 10, 2021 issue of the journal Astrophysical Journal Supplement Series. It was carried out using the measurement by the IBEX satellite of the energetic neutral atoms (ENA) which are the inevitable result of violent collisions between the particles of the solar wind and the elements blown by the interstellar wind.

The intensity of this signal depends on the severity of the solar wind that hammers the heliosheath. When the waves hit the shaft, the number of ENA increases and IBEX can register it.

“The solar wind signal sent by the Sun varies in strength, forming a unique pattern”, Dr. Reisenfeld adds. “IBEX will see the same pattern in the returning ENA signal, two to six years later, depending on the ENA energy and the direction IBEX is looking through the heliosphere. This time difference is how we found the distance to the source region of the ENA in a particular direction.

These sonar-like methods were used by Reisenfeld and his team to construct their 3D map using information collected over a ten-year solar cycle from 2009 to 2019.

“By doing so, we are able to see the edge of the heliosphere in the same way that a bat uses sonar to ‘see’ the walls of a cave,” Dr. Reisenfeld said. “The reason it takes so long for the signal to get back to IBEX is because of the vast distances involved.”

The new 3D map from Los Alamos reveals that the minimum distance from the Sun to the heliopause is about 120 AU (astronomical units) upwind, and extends a minimum of 350 AU in the opposite direction, which also represents the limiting distance for this sounding technique.

“Physical models have theorized this limit for years,” noted Dr. Reisenfeld. “But this is the first time we’ve been able to measure it and make a 3D map of it.”