Using data from NASA’s Interstellar Boundary Explorer (IBEX) satellite, astronomers have mapped the boundary of the heliosphere, the vast region of space that surrounds the solar system and is filled with the solar wind.
We have known for a long time that the shape of the heliosphere, despite its name, is not spherical, but it has taken us much longer to realize its true shape. This massive bubble that encloses the solar system, stretches for tens of millions of kilometers and protects us from harmful stellar radiation.
Now, for the first time in history, a team of scientists has managed to map the limit of the heliosphere , giving us a clearer idea of the forces that sculpt our bubble from the outside. As the solar wind pushes outward from the Sun, it gradually loses strength and eventually becomes unable to overcome even the weak winds of interstellar space. This place is called the heliopause, and the inner area is the heliosphere.
“Physical models have theorized this limit for years,” says astronomer Dan Reisenfeld of the Los Alamos National Laboratory. “But this is the first time that we have been able to measure it and make a three-dimensional map.”
The groundbreaking map was produced by scientists at Los Alamos National Laboratory (LANL), who took advantage of decade-long data collected during a full solar cycle between 2009 and 2019. This information was collected by NASA’s IBEX satellite, which was launched in 2008 with the intention of studying the interactions between the interstellar medium and the solar winds emanating from the Sun up to 1.6 million km / h.
To make this measurement, they used a technique similar to the way bats use sonar. “Just as bats send sonar pulses in all directions and use the return signal to create a mental map of their environment, we use the solar wind from the Sun, which rises in all directions, to create a map of the heliosphere”, Reisenfeld comments.
Solar winds are made up of protons, electrons, and alpha particles and shape the heliosphere into a bubble shape. And it is that the Sun constantly launches a stream of charged particles, a supersonic wind of ionized plasma, into space that, as we see, loses strength with distance, in what we call a heliopause.
What shape is the heliosphere then?
We now know that its shape is comet-like after all , with a tail at least 350 astronomical units long (that’s the current limit of the IBEX’s range), although the length of the tail is impossible to measure. And the minimum radial distance to the ‘tip’ of the heliopause appears to be around 110 to 120 astronomical units (AU), a figure consistent with the Voyager space probe crossovers. For reference, Neptune’s orbit is about 60 AU wide.
The IBEX mission is ongoing and will continue until at least 2025.
Referencia: “A Three-dimensional Map of the Heliosphere from IBEX” by Daniel B. Reisenfeld, Maciej Bzowski, Herbert O. Funsten, Jacob Heerikhuisen, Paul H. Janzen, Marzena A. Kubiak, David J. McComas, Nathan A. Schwadron, Justyna M. Sokół, Alex Zimorino and Eric J. Zirnstein, 10 June 2021, The Astrophysical Journal.
DOI: 10.3847/1538-4365/abf658
