NASA's IBEX observations pin down interstellar magnetic field

February 27, 2016
(Artist concept) Far beyond the orbit of Neptune, the solar wind and the interstellar medium interact to create a region known as the inner heliosheath, bounded on the inside by the termination shock, and on the outside by the heliopause. Credit: NASA/IBEX/Adler Planetarium

Immediately after its 2008 launch, NASA's Interstellar Boundary Explorer, or IBEX, spotted a curiosity in a thin slice of space: More particles streamed in through a long, skinny swath in the sky than anywhere else. The origin of the so-called IBEX ribbon was unknown - but its very existence opened doors to observing what lies outside our solar system, the way drops of rain on a window tell you more about the weather outside.

Now, a new study uses IBEX data and simulations of the interstellar boundary - which lies at the very edge of the giant magnetic bubble surrounding our solar system called the - to better describe space in our galactic neighborhood. The paper, published Feb. 8, 2016, in Astrophysical Journal Letters, precisely determines the strength and direction of the magnetic field outside the heliosphere. Such information gives us a peek into the magnetic forces that dominate the galaxy beyond, teaching us more about our home in space.

The new paper is based on one particular theory of the origin of the IBEX ribbon, in which the particles streaming in from the ribbon are actually solar material reflected back at us after a long journey to the edges of the sun's magnetic boundaries. A giant bubble, known as the heliosphere, exists around the sun and is filled with what's called , the sun's constant outflow of ionized gas, known as plasma. When these particles reach the edges of the heliosphere, their motion becomes more complicated.

This simulation shows the origin of ribbon particles of different energies or speeds outside the heliopause (labeled HP). The IBEX ribbon particles interact with the interstellar magnetic field (labeled ISMF) and travel inwards toward Earth, collectively giving the impression of a ribbon spanning across the sky. Credits: SwRI/Zirnstein

"The theory says that some solar wind protons are sent flying back towards the sun as neutral atoms after a complex series of charge exchanges, creating the IBEX ribbon," said Eric Zirnstein, a space scientist at the Southwest Research Institute in San Antonio, Texas, and lead author on the study. "Simulations and IBEX observations pinpoint this process - which takes anywhere from three to six years on average - as the most likely origin of the IBEX ribbon."

Outside the heliosphere lies the , with plasma that has different speed, density, and temperature than solar wind plasma, as well as neutral gases. These materials interact at the heliosphere's edge to create a region known as the inner heliosheath, bounded on the inside by the termination shock - which is more than twice as far from us as the orbit of Pluto - and on the outside by the heliopause, the boundary between the solar wind and the comparatively dense interstellar medium.

Some solar wind protons that flow out from the sun to this boundary region will gain an electron, making them neutral and allowing them to cross the heliopause. Once in the interstellar medium, they can lose that electron again, making them gyrate around the interstellar magnetic field. If those particles pick up another electron at the right place and time, they can be fired back into the heliosphere, travel all the way back toward Earth, and collide with IBEX's detector. The particles carry information about all that interaction with the interstellar magnetic field, and as they hit the detector they can give us unprecedented insight into the characteristics of that region of space.

"Only Voyager 1 has ever made direct observations of the interstellar magnetic field, and those are close to the heliopause, where it's distorted," said Zirnstein. "But this analysis provides a nice determination of its strength and direction farther out."

The directions of different ribbon particles shooting back toward Earth are determined by the characteristics of the interstellar magnetic field. For instance, simulations show that the most energetic particles come from a different region of space than the least energetic particles, which gives clues as to how the interstellar magnetic field interacts with the heliosphere.

The IBEX ribbon is a relatively narrow strip of particles flying in towards the sun from outside the heliosphere. A new study corroborates the idea that particles from outside the heliosphere that form the IBEX ribbon actually originate at the sun – and reveals information about the distant interstellar magnetic field. Credits: SwRI

For the recent study, such observations were used to seed simulations of the ribbon's origin. Not only do these simulations correctly predict the locations of neutral ribbon particles at different energies, but the deduced interstellar magnetic field agrees with Voyager 1 measurements, the deflection of interstellar neutral gases, and observations of distant polarized starlight.

However, some early simulations of the interstellar don't quite line up. Those pre-IBEX estimates were based largely on two data points - the distances at which Voyagers 1 and 2 crossed the termination shock.

"Voyager 1 crossed the termination shock at 94 astronomical units, or AU, from the sun, and Voyager 2 at 84 AU," said Zirnstein. One AU is equal to about 93 million miles, the average distance between Earth and the sun. "That difference of almost 930 million miles was mostly explained by a strong, very tilted pushing on the heliosphere."

But that difference may be accounted for by considering a stronger influence from the solar cycle, which can lead to changes in the strength of the solar wind and thus change the distance to the termination shock in the directions of Voyager 1 and 2. The two Voyager spacecraft made their measurements almost three years apart, giving plenty of time for the variable solar wind to change the distance of the .

"Scientists in the field are developing more sophisticated models of the time-dependent solar wind," said Zirnstein.

The simulations generally jibe well with the Voyager data.

"The new findings can be used to better understand how our space environment interacts with the interstellar environment beyond the heliopause," said Eric Christian, IBEX program scientist at NASA's Goddard Space Flight Center in Greenbelt, Maryland, who was not involved in this study. "In turn, understanding that interaction could help explain the mystery of what causes the IBEX ribbon once and for all."

The Southwest Research Institute leads IBEX with teams of national and international partners. NASA Goddard manages the Explorers Program for the agency's Heliophysics Division within the Science Mission Directorate in Washington.

Explore further: The Sun's ripple effect

More information: E. J. Zirnstein et al. LOCAL INTERSTELLAR MAGNETIC FIELD DETERMINED FROM THE RIBBON , The Astrophysical Journal (2016). DOI: 10.3847/2041-8205/818/1/L18

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Whydening Gyre
5 / 5 (4) Feb 27, 2016
"That difference of almost 930 million miles was mostly explained by a strong, very tilted interstellar magnetic field pushing on the heliosphere."
I'm a little confused.
Inasmuch as the Solar system is tilted 63' relative to the galactic, why do "artist conceptions" (as well as other diagrams I've seen) always show the heliosphere's leading edge matching the SOLAR plane...?
Considering that geometric factor, along with the direction we are traveling around the galaxy, it would seem the helio sphere "teardrop" shape should follow a more "north to south" appearance.
Do they just draw it with a "Interstellar Space Interactions for Dummies" mentality?
Apologies in advance if that sounded "dumb" - I just woke up...
katesisco
1.4 / 5 (9) Feb 27, 2016
What I attribute these 'constant new discoveries' to is the lack of a way forward that forced a single position as to have a direction. New means wrong but that is unacceptable as confounds the way. So adherence to the way even tho it is wrong means the correct is just added in without any meaningful look back to revision.
My theory suggest the Oort shell is a meaningful barrier that recharges and reflects back most if not all solar particles. The solar system is closed, in other words. To envision a stream of recharged particles encountering Earth would seem to indicate that this is a reduced form of the once-all encompassing bounce-back of solar particles.
I theorize that prior to Sol, a red giant star similar to Betelgeuse experienced an electrical compression that produced a reduced magnatar in its place, along with the rocky planets from the metalized gases. Perhaps the 3 extinction events were sourced from this energized 'bounce-back.'
torbjorn_b_g_larsson
4.4 / 5 (7) Feb 27, 2016
I wonder how Planet Nine - if it exists - a gassy planet, interact with the interstellar medium and its magnet fields? We could get rare data out of it, if and when we can make closer observations!

@WG: I'm not sure about the geometry - having just woke up =D - but the solar plane would align with the stellar-dynamo dipole. I.e. the heliosphere main field strength would lie nearly aligned with the planetary plane.

Other oddities here is that they left Pluto in. (But as long as New Horizons's scientists report Pluto data, so 1.5 year more, NASA would tend to promote Pluto, so maybe not a mistake.)

@katesisco: If you have a theory that is well tested by observations after numerical predictions, you must publish it in peer review to influence people. For the time being I note that the Oort cloud is too disperse and magnetically inactive to be a meaningful influence on magnetic fields or charged particles. That is why we see no such return particles, obviously.
Whydening Gyre
5 / 5 (4) Feb 27, 2016
TBGL.
I was referring to an ecliptic relationship (I think). Ours vs galactic to start.
HannesAlfven
2.6 / 5 (12) Feb 27, 2016
They seem to not be seriously engaging the implication that they are observing a larger structure to our solar system whose size defies a purely circumstantial explanation. Why is the ribbon there, to begin with? Gases under the guidance of gravity do not form such structures; it is the plasma state of matter which more logically involves magnetic fields and streams of charged particles. Why not engage the observations using laboratory plasma physics observations? Probably because the scientist did not focus upon electrodynamic plasmas in their university training, but will this be true of the following generations of scientists? Probably not.
AGreatWhopper
3.7 / 5 (6) Feb 27, 2016
Getting bad when the valid comments are less than half of the total.
thingumbobesquire
1.9 / 5 (8) Feb 27, 2016
The anti-science mob is hell bent on tearing down the US space program. Yet it is the only way forward for humanity. China is planning on mining Helium 3 on the moon for fusion energy fuel. Meanwhile, the US manned space program has been shut down under the administration of the latter day Luddite Barack Obama.
Captain Stumpy
3.9 / 5 (7) Feb 27, 2016
why do "artist conceptions"
@Whyde
not everyone is as attentive to detail as they should be... this applies to artists every bit as much as anyone except for those who's job it is to actually be detail oriented (like science research)

take the eu claims about Shoemaker as an example:
how can you claim that Shoemaker-Levy was broken apart by "plasma discharges" when it was the most observed planetary collision in history and not one report anywhere demonstrate with any evidence that it died in a plasma discharge

worse still it exactly matched the Roche limit predictions... so, gravity predicted it, and observations exactly matched what the prediction was..
so... the eu claims this is evidence of plasma discharge because [insert random quote from cd about how AStro's don't know plasma physics] AND [insert claim about conspiracy and or incompetence]

Captain Stumpy
3.9 / 5 (7) Feb 27, 2016
So adherence to the way even tho it is wrong means the correct is just added in without any meaningful look back to revision
@kate
EITHER:
1- research scientists are all incompetent
2- research scientists are all in a conspiracy to deceive you
3- research scientists know something you don't
potholer54
https://www.youtu...dYvz0VwQ

My theory suggest
you mean hypothesis, right?
if it is testable, do what TGBL said...
a red giant star similar to Betelgeuse experienced an electrical compression
where did the "electrical compression" come from and why did it happen?
is it testable?
what would be the effects and what should we see that would support or falsify your conclusions?
Perhaps the 3 extinction events
before you try to tie this into extinction events, lets actually find a means to test the validity of the hypothesis and seek evidence

TheGhostofOtto1923
4 / 5 (4) Feb 27, 2016
Interstellar magnetic field

-why that means ELECTRICITY, doesn't it?

But whaddu I know...
Whydening Gyre
5 / 5 (6) Feb 27, 2016
Interstellar magnetic field

-why that means ELECTRICITY, doesn't it?

But whaddu I know...

Magnetic field + MATTER equals electricity.
And like you, "But whaddu I know"...:-)
Whydening Gyre
5 / 5 (2) Feb 27, 2016
I wonder how Planet Nine - if it exists - a gassy planet, interact with the interstellar medium and its magnet fields? We could get rare data out of it, if and when we can make closer observations!

I imagine it isn't so "gassy" out in the very cold of space...:-)
@WG: I'm not sure about the geometry - having just woke up =D - but the solar plane would align with the stellar-dynamo dipole. I.e. the heliosphere main field strength would lie nearly aligned with the planetary plane.

I agree, however I think there might be distortion aligned with the direction of our path (which aligns with the galactic)

Whydening Gyre
3.7 / 5 (3) Feb 27, 2016
I agree, however I think there might be distortion aligned with the direction of our path (which aligns with the galactic)

It just hit me. The source of most of the "interstellar wind" is from the center of the galaxy, itself. Thus showing the bow shock as along the solar system plane with some minor trail away due to our path...
SHREEKANT
1 / 5 (2) Mar 01, 2016
C. "particles streaming in from the ribbon ..... reflected back at us ...edges of the sun's magnetic boundaries."

2nd OPINION:

I CONTRADICT,, MOSTLY it is NOT. It is the MIXTURE of all …. Coming from different sources due to PARTICULAR condition [explained in my presentation]

Reference:

1. It is the part of my oral presentation on "Regeneration of Star & formation of a Solar system – a Potter man's concept" in International Science conference ["Planetary System – a synergistic view"] at Vietnam [19th-25th , July'15]

2. "GRAVITY"- a PUSHING FORCE [-a "Layman concept of Unified Dark Energy"]" sent on 17th, Aug.'2013 to one of the reputed Journal 'General Relativity and Gravitation

D. "The sun's ...ch the edges of the Heliosphere, their motion becomes more complicated. "

2nd OPINION:

pl. ref.

http://swarajgrou..._29.html

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