At first glance, it looks like something out of a strange autopsy. A strange organ cut from the thorax of the xenomorph, under the flickering lights of an operating room in a top secret government installation, with venous vines hanging to the floor, dripping viscous mucus. (X-Com anyone?)
But no, it’s just our solar system.
This strangely fascinating shape is actually a graphic representation of what our solar system looks like, or rather the magnetic bubble that surrounds our solar system. It is a representation of the heliosphere, a massive bubble cut into space by the constant outflow of the sun.
They call it the ‘deflated croissant’ model.
The problem with healing the heliosphere is that we are in it. The rim is more than 16 billion km (10 billion miles) away. It’s only thanks to the few Voyager spaceships that we only have data from outside the heliosphere. Voyager 1 left the helipad behind and entered interracial space in August 2012, and Voyager 2 did the same in November 2019.
There are missions dedicated to studying the heliosphere, such as NASA’s IBEX, as Interstellar Boundary Explorer. There are complex interactions where the heliosphere hits the interstellar space, a region called heliopause. IBEX studies what are called energy neutral atoms. They are made as cosmic rays from outside our solar system meet charged particles from inside our solar system. Since these energetic neutral atoms are made by interactions with the interstellar medium (ISM), they serve as a kind of proxy for measuring the edge of the heliosphere.
But the data of those interactions are complex. It must feed into computer models to come up with all the sensible predictions about the nature and form of the heliosphere. NASA and the NSF have funded an effort to make sense, called the SHIELD Drive Science Center, at Boston University.
A study published earlier this year presents some of the new results on the heliosphere. The title is “A small and round heliosphere suggested by magnetohydrodynamic modeling of pick-up ions.” The lead author is Merav Opher, professor of astronomy at Boston University. The study is published in the journal Nature Astronomy.
Scientists once thought that the heliosphere was as shaped as a comet. As our solar system moves through space, the sun’s outflow meets the ISM and creates an arc shock like an arc wave at the front, and a heliotail at the rear, reminiscent of the tail of a comet. .
“The shape of the heliosphere has been studied over the past six decades,” the authors explain in their paper. “There has been a consensus since the pioneering work of Baranov and Malama that the heliosphere form is comet-like.”
But this new research shows us a different heliosphere. More recent evidence, the authors point out, shows that the heliosphere contains two jet-like structures.
Together with data from IBEX, the researchers used data from Cassini and New Horizons in their new study. They are both planetary missions, but they still have data on the solar system. In Cassini’s case, it measures particles that return to the inner solar system from interactions with the ISM. “Cassini’s observations of energy neutral atoms further suggest that the heliosphere has no tail,” they explain.
New Horizons measure what are called pickup ions (PUIs). PUIs are a critical part of this study. They are made when the sun moves through the partially ionized medium. They exchange charges with the solar wind, and this creates a population of hot pick-up ions (PUIs), which are a different temperature than the solar wind ions.
When Voyager 2 crossed the border into interstellar space, it appeared that the pressure at the heliosheath is dominated by these PUIs. But at that time, it was not investigated how the PUIs formed the heliosphere. That’s what this study did, and that’s how we got this strange new image from our heliosphere.
In the papers, the authors state that “The new model reproduces both the properties of the PUIs, based on the observations of the New Horizons, and the solar wind ions, based on the observations of the spaceship Voyager 2, such as the data from the solar-like magnetic fields outside the heliosphere at Voyager 1 and Voyager 2. ”
The PUIs are much hotter than other particles in the solar wind, and that difference is a key to this work.
“There are two liquids mixed together. You have one component that is very cold and one component that is much hotter, the pickup ions, “lead author Opher said in a press release.” If you have some cold liquid and hot liquid, and you put them in. ” “space, they will not mix – they will usually evolve separately. What we did was separate these two components from the solar wind and model the resulting 3D shape of the heliosphere.”
Instead of a nice, clean kind of shape, we get this. Rather than an elongated, spherical shape with a tail, we have a sort of deflated croissant shape. A bulbous, organic radiance that resembles a sort of organ.
“Because the pick-up ions dominate the thermodynamics, everything is very spherical. But because they leave the system completely behind the termination coil, the whole heliosphere deflates, ‘Opher said.
While this new image of the heliosphere is purely graphically interesting, it is also scientifically important. This is because of the important role that the heliosphere plays.
Outside the heliosphere, cosmic rays are created by energetic events in other Solar Systems. Cosmic rays are high-energy protons and atomic nuclei that move through space at relativistic speeds. Things like supernovae make them, and they travel outward in all directions.
Cosmic rays are dangerous, and the heliosphere is our shield against them. The heliosphere absorbs about 75% of the cosmic rays that pass through us, but those that pass through can be very disruptive. On Earth, we are most protected from cosmic rays by our magnetosphere and our atmosphere. But for satellites, spacecraft, and astronauts, the danger is real.
Not only do cosmic rays damage electronics, but exposure to them increases cancer risk for astronauts. And they are such high-energy parts that it is difficult to protect astronauts from them. Cosmic rays are one of the major dangers for long-term spaceflight, due to the increased risk of cancer.
There is also some evidence that increases in cosmic rays as the solar system moves relative to the galactic plane in the past have led to extinction. Some researchers also believe that supernovae explosions in the past exposed the Earth to much higher levels of cosmic rays, perhaps triggering the extinction of marine megafauna in the Pliocene. But much of that research is controversial.
A better understanding of our own heliosphere could also help us understand exoplanet viability. Cosmic radiation can make planets uninhabitable, even those we find in the “Goldilocks Zone” dying stars. While we gain a better understanding of the shape and function of our own heliosphere, we can apply this knowledge to other solar systems, giving us a more sophisticated way of looking at liveability and life.
As it stands now, we do not know enough about our own heliosphere, including its shape, to accurately characterize other heliospheres.
But an upcoming NASA mission should help. It’s called IMAP, as Interstellar Mapping and Acceleration Probe. IMAP is scheduled for launch in 2024, and it will map the particles flowing to Earth from the boundaries of the heliosphere.
The DRIVE Science Center will play a role in the IMAP mission. Opher and his colleagues at DRIVE are making a testable model of the heliosphere in time for the deployment of IMAP in 2024. Their model will include more detailed predictions of the shape of the heliosphere and other properties. Scientists can then use IMAP observations to test them.
“Future remote and in-situ measurements may test the reality of a circular heliosphere,” the authors wrote in the conclusion to their paper. “… future missions such as the Interstellar Mapping and Acceleration Probe will become ENA (Energetic Neutral Atoms, which become PUIs after charge exchange) at higher energy than current missions and so ENAs can investigate from deep into the heliosphere tail. Thus, further exploration of the global structure of the heliosphere will arrive and will put our model to the test. ‘
