Scientists find strange shapes at the boundary to interstellar space

Scientists discovered unknown structures and ripples at the border of the heliosphere, the boundary between our solar system and interstellar space.
Fabienne Lang
Heliosphere
Heliosphere

NASA 

Strange ripples and oblique-angled structures have been discovered at the border of our solar system, and the large expanse of interstellar space that begins beyond it, explains a new study.

Scientists have picked up data that "are intriguing and potentially controversial," per VICE, after observing results showing that the heliosphere's border, a giant bubble around the Sun and its planets, was shifting in strange ways.

"NASA studies the heliosphere to better understand the fundamental physics of the space surrounding us - which, in turn, provides information regarding space throughout the rest of the universe, as well as regarding what makes planets habitable," explains the space government agency.

Insight into the heliosphere

What is the heliosphere? Our Sun sends out a constant flow of charged particles known as the solar wind. This solar wind travels past all the planets across to some three times the distance to Pluto. In this region, called the heliopause, they are then impeded by the interstellar medium.

Just as the Earth's magnetic field protects our planet from the ravages of the solar wind, the heliosphere protects the solar system from the interstellar (or galactic) wind. And as we previously reported, "Without the heliosphere, life would certainly have evolved differently - and maybe not at all."

The only artificial objects to cross this boundary are NASA's Voyager 1 and 2 probes, launched nearly 50 years ago in 1977. To this day, the probes send information from past the heliosphere, and their only main limitation is that they can only send dispatches from their precise locations.

Along with this data, scientists have also been able to map out the broader contours of the heliopause by searching for emissions made by energetic neutral atoms (ENAs). These are created by the blend of solar and interstellar winds. There is still a lot to learn and see in this domain.

The new study

This is where the new study, led by a research scholar in space physics at Princeton University, Eric Zirnstein, comes in. Zirnstein and his team used data from 2014 when a months-long spike in the dynamic pressure of the solar wind caused intriguing new details to show up about the heliopause region.

This anomaly was captured by NASA's Interstellar Boundary Explorer (IBEX) satellite, showcasing a dramatic brightening of ENAs after this pressure by the solar wind. In turn, weird ripples and oblique shapes to the heliosphere structure showed up, in direct conflict with previous structure models. Zirnstein's team observed these IBEX observations and were the ones to discover these ripples and oblique distortions. These variations can reach a mighty ten astronomical units (AU) – one AU is equivalent to the distance between the Sun and Earth.

The team was initially extremely surprised, but "when we consider how dynamic the solar wind actually is, this probably shouldn’t have been too surprising—but it sure was interesting to see it," explained Zirnstein to VICE.

Exactly what is shaping these variations is still unknown. The team continues its research on the matter, with plans to better understand these ripples and oblique angles, as well as waiting for another major change in solar wind power - like the one from 2014.

As we live inside this heliosphere, which protects our solar system from harmful cosmic radiation, it is vital to map out its contours and understand the complex forces that shape it.

The study was published in the journal Nature.

Abstract:

The analysis reveals rippled HTS and HP surfaces that are oblique with respect to the local interstellar medium upwind direction, with significant asymmetries in the heliosphere structure compared to steady-state heliosphere models. We estimate that the heliosphere boundaries contain roughly ten astronomical unit-sized spatial variations, with slightly larger variations on the HTS surface than the HP and a large-scale, southwards-directed obliquity of the surfaces in the meridional plane. Comparisons of the derived HTS and HP distances with Voyager observations indicate substantial differences in the heliosphere boundaries in the northern versus southern hemispheres and their motion over time.

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