Surprise! IBEX Finds No Bow ‘Shock’ Outside our Solar System

by Nancy Atkinson on May 10, 2012

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New data from NASA's Interstellar Boundary Explorer (IBEX) shows that the heliosphere moves through space too slowly to form a bow shock. Credit: Southwest Research Institute.

For years, scientists have thought a bow “shock” formed ahead of our solar system’s heliosphere as it moved through interstellar space – similar to the sonic boom made by a jet breaking the sound barrier. But new data from NASA’s Interstellar Boundary Explorer (IBEX) shows that our system and its heliosphere move through space too slowly to form a bow shock, and therefore does not exist. Instead there is a more gentle ‘wave.’

“While bow shocks certainly exist ahead of many other stars, we’re finding that our Sun’s interaction doesn’t reach the critical threshold to form a shock,” said Dr. David McComas, principal investigator of the IBEX mission, “so a wave is a more accurate depiction of what’s happening ahead of our heliosphere — much like the wave made by the bow of a boat as it glides through the water.”

From IBEX data, McComas and his team were able to make refinements in relative speed of our system, as well as finding more information about the local interstellar magnetic field strength. IBEX data have shown that the heliosphere actually moves through the local interstellar cloud at about 52,000 miles per hour, roughly 7,000 miles per hour slower than previously thought. That is slow enough to create more of a bow “wave” than a shock.

Bow shocks exist around other astrospheres, as seen in these images taken by multiple telescopes. New IBEX data show that our heliosphere moves through interstellar space too slowly to produce a bow shock, creating more of a “wake” as it travels through space. Image courtesy of Southwest Research Institute

Another influence is the magnetic pressure in the interstellar medium. IBEX data, as well as earlier Voyager observations, show that the magnetic field is stronger in the interstellar medium requiring even faster speeds to produce a bow shock. Combined, both factors now point to the conclusion that a bow shock is highly unlikely.

This new finding perhaps correlates with earlier investigations by the CLUSTER mission, which found the bow shock was remarkably thin.

The IBEX team combined its data with analytical calculations and modeling and simulations to determine the conditions necessary for creating a bow shock. Two independent global models — one from a group in Huntsville, Ala., and another from Moscow — correlated with the analytical findings.

Their paper was published today in the journal Science.

How does this new finding change our understanding of our heliosphere?

“It’s too early to say exactly what this new data means for our heliosphere,” McComas said. “Decades of research have explored scenarios that included a bow shock. That research now has to be redone using the latest data. Already, we know there are likely implications for how galactic cosmic rays propagate around and enter the solar system, which is relevant for human space travel.”

Source: SwRI

About 

Nancy Atkinson is Universe Today's Senior Editor. She also is the host of the NASA Lunar Science Institute podcast and works with Astronomy Cast. Nancy is also a NASA/JPL Solar System Ambassador.

Scott Romesburg May 10, 2012 at 7:01 PM

It makes sense..space is a vacuum, nothing really to make resistance.

Torbjörn Larsson May 10, 2012 at 7:50 PM

I’m not sure what you mean. Obviously from the photos stars can for bow shocks, and from earlier observations we still have a termination shock.

Space is filled with interstellar media and magnetic fields, and for example magnetic fields will encounter resistance and vice versa when they interact with ionized media.*

—————-
If you want to dig deep in the physics, Standard Model particle mass are mostly from the resistance they feel when they interact with the Higgs field of the vacuum. Not the Higgs particles’ mass themselves though.

zkank May 10, 2012 at 9:50 PM

How about gravity?

Suvankar Sen May 11, 2012 at 7:18 AM

You must not forget that in space, though it seems empty, gets triggered dur to strong gravitational waves. Our solar system should have triggered a massive shock wave, but somehow, it doesn’t happen so

Kawarthajon May 11, 2012 at 8:05 PM

The space around the Sun is a vacuum, but you should not, therefore, assume that it is empty. There’s lots of stuff around the Sun in the vacuum – light, particles streaming from the sun, dust, micrometerites, particles streaming into the solar system from other systems, not to mention magnetic and gravitational fields. Lots of stuff to come into conflict with each other. This article doesn’t say there’s no resistence, just that there is not a clearly defined border between the Sun’s stuff and the interstellar medium’s stuff, as had previously been assumed.

BTW, IBEX is really, really, really cool! I love hearing about IBEX’s discoveries!!

Torbjörn Larsson May 10, 2012 at 7:48 PM

That would certainly make sense of the observations (from IBEX et al) that the structures from the heliosphere and outwards are, AFAIK, ellipsoid instead of tailed.

We live in a bubble.

Lawn Boy May 10, 2012 at 8:27 PM

I quote from the article:

“But new data from NASA’s Interstellar Boundary Explorer (IBEX) shows that our system and its heliosphere move through space too slowly to form a bow shock, AND THEREFORE DOES NOT EXIST.”

I don’t exist, therefore I am not.

So, goodbye.

fitzgeraldalberto May 11, 2012 at 2:18 AM

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RemyVTR15 May 11, 2012 at 12:51 PM

I hope this gets people really talking… Here’s another reputed ‘fact’ (theory) that was ironclad… and is now turned on its ear.
Theories are just that.

Torbjörn Larsson May 11, 2012 at 8:20 PM

That is erroneous. And it is due to a naive model of facts and theories, as well as a fallacy of composition.

Theories are set of facts, observations used to predict new observations. They accrue around facts of observed processes. An example is the observable fact of the process of gravity, and theories that predict such observations, say general relativity.

What happened here is that we have a theory that predicted different outcomes, and instead of one likely outcome as based on previous observations a more unlikely one is predicted by newer observations. There is nothing “turned on its ear” as you can see from the images and read from the text: the model theory is kept, and it is its pervasive and continued use that “has to be redone using the latest data”.

If you are really serious about testing, the old theory with its particular parameter set failed in a test and the new theory looks pretty much the same.

And as for the fallacy, while theories are what makes science work, there is no such granularity when looking at it as a process. If some facts or theories are mistaken has never meant, nor will ever mean, that other facts or theories or even science itself will not work.

Jeff Boerst May 11, 2012 at 9:05 PM

Applying small (very) area effects like our solar system’s moving through the interstellar medium to large ones like the Universe itself expanding is like saying, “I’m sitting still on my chair and typing on my computer, so that means that plate tectonics are nonsense”. Besides, the Universe expands per SPACE ITSELF doing so, not the matter (objects) WITHIN it. These two ideas are mutually exclusive. And the bow shock theory wasn’t “iron clad” as are no ideas in science, it was merely the most likely one based on the data we had to the point this current research came out. That’s what science does: it forms understandings based on what we know at the time and is always searching to gain more data to either fine-tune or negate current ideas. And the word, “theories” in SCIENCE (ie: outside of idle conversation by non-scientists) means far more than merely, “Theories are just that.” They are based on known principles and backed up with observation which gets modified alongside our technological advances. Gravity is a theory as are evolution and quantum physics. We can directly see gravity’s effects, a good amount of medicine is based on ideas put forth by evolution and electronics (from the transistor and the diode to the latest/latest high tech patent) WOULD NOT WORK AT ALL if quantum theory was “Just That”… Amen.

Erwin Maulana R May 11, 2012 at 8:56 PM

If that is correct.. then the science book must re-written

Jeff Boerst May 11, 2012 at 9:07 PM

A-MEN! Well put.

Lawn Boy May 12, 2012 at 2:12 AM

Theories failing tests isn’t a problem. Theories fail tests all the time. The theories are revised or discarded and science goes on.

Theories being revised AFTER engineering based on those theories has begun is where the “uh-oh” comes in. I doubt there was a lot of engineering going on based on the “Bow Shock” theory. So no big whup.

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