From NASA Science News January 15, 2010: Last year, when NASA’s IBEX (Interstellar Boundary Explorer) spacecraft discovered a giant ribbon at the edge of the solar system, researchers were mystified. They called it a “shocking result” and puzzled over its origin.
Now the mystery may have been solved.
“We believe the ribbon is a reflection,” says Jacob Heerikhuisen, a NASA Heliophysics Guest Investigator from the University of Alabama in Huntsville. “It is where solar wind particles heading out into interstellar space are reflected back into the solar system by a galactic magnetic field.”
Heerikhuisen is the lead author of a paper reporting the results in the Jan. 10th edition of the Astrophysical Journal Letters.
“This is an important finding,” says Arik Posner, IBEX program scientist at NASA Headquarters. “Interstellar space just beyond the edge of the solar system is mostly unexplored territory. Now we know, there could be a strong, well-organized magnetic field sitting right on our doorstep.”
The IBEX data fit in nicely with recent results from Voyager. Voyager 1 and 2 are near the edge of the solar system and they also have sensed strong* magnetism nearby. Voyager measurements are relatively local to the spacecraft, however. IBEX is filling in the “big picture.” The ribbon it sees is vast and stretches almost all the way across the sky, suggesting that the magnetic field behind it must be equally vast.
Although maps of the ribbon (see below) seem to show a luminous body, the ribbon emits no light. Instead, it makes itself known via particles called “energetic neutral atoms” (ENAs)–mainly garden-variety hydrogen atoms. The ribbon emits these particles, which are picked up by IBEX in Earth orbit.
Above: A comparison of IBEX observations (left) with a 3D magnetic reflection model (right). More images: data, model.
The reflection process posited by Heerikhuisen et al. is a bit complicated, involving multiple “charge exchange” reactions between protons and hydrogen atoms. The upshot, however, is simple. Particles from the solar wind that escape the solar system are met ~100 astronomical units (~15 billion kilometers) away by an interstellar magnetic field. Magnetic forces intercept the escaping particles and sling them right back where they came from.
“If this mechanism is correct–and not everyone agrees–then the shape of the ribbon is telling us a lot about the orientation of the magnetic field in our corner of the Milky Way galaxy,” notes Heerikhuisen.
And upon this field, the future may hinge.
The solar system is passing through a region of the Milky Way filled with cosmic rays and interstellar clouds. The magnetic field of our own sun, inflated by the solar wind into a bubble called the “heliosphere,” substantially protects us from these things. However, the bubble itself is vulnerable to external fields. A strong magnetic field just outside the solar system could press against the heliosphere and interact with it in unknown ways. Will this strengthen our natural shielding—or weaken it? No one can say.
Right: An artist’s concept of interstellar clouds in the galactic neighborhood of the sun. [more]
“IBEX will monitor the ribbon closely in the months and years ahead,” says Posner. “We could see the shape of the ribbon change—and that would show us how we are interacting with the galaxy beyond.”
It seems we can learn a lot by looking in the mirror. Stay tuned to Science@NASA for updates.
h/t to Leif Svalgaard
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Conflating the two (field and wave)?
Do you mean to differentiate between a propagating EM ‘wave’ (and those conditions which lead up to it) versus a static ‘field’?
– from an eng who has played with NEC2/MOM and is now looking at FDTD techniques for antenna/resonant structure analysis.
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vukcevic (09:13:54) :
Undulation in the ‘space ribbon’ appear to be corresponding to the undulation perceivable in HCS.
http://www.vukcevic.talktalk.net/LFC3.htm
I’m utterly amazed that you don’t get it. One last time: the undulation in HCS moves in longitude and sweeps around completely in 25 days, while the ribbon stays put. Here http://www.leif.org/research/HCS%20projected%20onto%20Heliopause.png is what the projection of the HCS at Earth [or near the Sun] would look like if the HCS just moved out radially from the Sun. I assume for simplicity an idealized two-sector structure. The Figure shows in a latitude (Y-axis) and longitude (X-axis) plot where the HCS would be as it is rotating. Curves are one day apart.
Since you don’t get this first step, the rest of your comment is moot.
Leif Svalgaard (09:57:48) :
I was talking about particles moving radialy, until they get deflected by magnetosphere, while you are ‘stuck’ in HCS spiral groove. HCS plane is a narrow plane separating particles of two different polarity, so current flow is immaterial, it is particles that are ‘reflected back’ by Galactic MF, and the current will take care of itself.
We are obviously either accidentally or intentionally on two different frequencies, so communication is breaking down. Have a nice day !
vukcevic (09:38:15) :
Magnetic line does not exist any more than an isobar on a weather chart or isohypse on a mountain side of a field map.
How is it possible to conduct an intelligent discourse when your concepts are so wrong-headed…
I’ll try [although I fear that you’ll be lost again] to illustrate what is meant by ‘magnetic field lines’. Imagine for simplicity that the Earth had a simple dipolar field aligned with the rotation axis. Now ask: “does the magnetic field lines in your living room rotate with the Earth?” The answer is clearly ‘No’. To test this set up a coil and see if any current comes out of it during the 24-hour rotation.
So in your living room, magnetic field lines have no ‘individuality’ which is a prerequisite for existence [namely that you can point to one and follow it as it moves along]. They simply show the direction [and strength] of a static unchanging magnetic field and do not exist any more than contour lines on a map.
Now, in the polar caps of the Earth from about 100 km and up things are very different. The magnetic field of the Earth up there and beyond are connected to the solar wind and is swept into a long anti-sunward tail. The field lines in the tail have individuality, they can sometimes even be seen [as auroral streamers] and particles scuttle up and down the field lines and don’t jump to other lines. The field lines can even wiggle and wave in response to changing solar wind [and ionospheric winds too]. There is magnetic energy stored in the field lines as they are deformed by the solar wind. If you were to put a coil up there [at a fixed position e.g. 80N, 90W] a current would appear in that coil showing that the magnetic field is changing as the Earth [with the coil] is rotating with respect to the magnetosphere. The concept of ‘existence’ is subtle and often we adopt an operational definition: does an electron exist? yes, because we can capture a single one and follow it around, but in another sense it does not exist because that is just the name we give to some observed phenomenon. If two electrons exist, how come their properties [mass, charge, spin] can be be identical [to very many decimal places, e.g. mass = 9.10938188 × 10^-31 kg]. One can argue that only ONE electron exists in the Universe as a property of the Vacuum, and when we pull an electron out of the vacuum [shine enough light into a box and watch] then it is no wonder that they are all alike, because they are just manifestations of the same underlying reality.
Anyway, it is convenient to say that electrons exist and it is convenient to say that in a space plasma magnetic field lines exit too. And that is how we manage to intuit Mother Nature. We make images and analogies and sometimes they are useful [most of the time if well made], but sometimes they lead us astray. Scientists usually know when an image is no longer any good and can switch ‘gears’ as needed. Lay persons often do not appreciate this ‘flexibility of thought’.
vukcevic (10:16:14) :
HCS plane is a narrow plane separating particles of two different polarity, so current flow is immaterial, it is particles that are ‘reflected back’ by Galactic MF, and the current will take care of itself.
No, the HCS is a highly convoluted warped surface [no plane] that separates regions of space where the magnetic fields have different polarities [either ‘away’ from Sun along the spiral angle or ‘towards’ the Sun along the same spiral]. The magnetic field is radial near the Sun and azimuthal in the equatorial plane far from the Sun. The current in the HCS is just local particles that happen to be there and are gyrating along the field lines. The particles in the HCS are not reflected back towards the Sun [they are stuck on their field lines]. And you still don’t seem to grasp that the HCS where the ribbon is sweeps around in 25 days while the ribbon stays put: http://www.leif.org/research/HCS%20projected%20onto%20Heliopause.png
I don’t think you have much understanding if this, you talk about ‘particles of different polarities’…
We are obviously either accidentally or intentionally on two different frequencies, so communication is breaking down. Have a nice day !
Why you intentionally would do this is beyond me, but, hey, one comes across all kinds of people…
What is breaking down is your willingness to learn.
Leif Svalgaard (10:35:07) :
“How is it possible to conduct an intelligent discourse when your concepts are so wrong-headed…”
Impossible!
As I already mentioned : magnetic field is a three-dimensional while a line is an abstract mathematical two-dimensional entity. The second cannot represent the fundamental nature of the first.
But if you whish to have it your way, and be scientifically more accurate, at least have magnetic tubes.
While you are on about the E’s MF, I have added one or two more graphs (since your last download) from: http://www.vukcevic.talktalk.net/GandF.htm
Some of these are natures real work of art: I particularly like magnetic anomaly along the Equator,
http://www.vukcevic.talktalk.net/Global%20Mag%20Anomaly.gif
which I have in A3 pdf format, ready to print.
If anyone likes a .pdf copy just send an email [vukcevicu(at)yahoo.com]
Leif Svalgaard (16:18:57) :
Sometimes Mother Nature does not fulfill our deepest desires. It is not hand-waving, there really isn’t any effect. The Sun’s output is already a million times stronger than the energy in the solar wind and the ‘ribbon’ is way below that in turn. The ribbon consists of ordinary neutral Hydrogen atoms with a density millions of times smaller than the rarefied air in the best vacuum we can make.
Failure to communicate detected. Reformatting. Resending.
Let us say that I, as a researcher, wanted to obtain a value for cosmic radiation, particles / (area * time). It would occur to me to exclude a main source of particles, the Sun, thus I want to leave out the solar wind from the measurements. Since the solar wind is flowing directionally from the Sun, I can take my measurements “in the shade,” have my detectors shielded and pointed away from the Sun.
But now, with this article, I find that the solar wind is coming not just from the direction of the Sun, but is being reflected and sent back towards the Sun. Thus particles from the solar wind can enter my detectors and increase my counts. What I thought would just be cosmic radiation counts, are now (cosmic radiation + reflected solar wind) counts. How do I differentiate between the sources of particles?
Haven’t researchers been trying to get accurate counts of cosmic radiation for a while now? With this revelation of reflected solar wind, is it possible that earlier measurements of cosmic radiation have been inflated by these particles of reflected solar wind?
Solar wind: “It consists mostly of electrons and protons with energies usually between 10 and 100 eV.”
Cosmic radiation: “Almost 90% of all the incoming cosmic ray particles are simple protons, with nearly 10% being helium nuclei (alpha particles), and slightly under 1% are heavier elements, electrons (beta particles), or gamma ray photons. (…) Cosmic rays can have energies of over 10^20 eV, far higher than the 10^12 to 10^13 eV that man-made particle accelerators can produce.”
I have read of, for example, the 1912 research of Victor Hess where he looked for ionizing radiation during a balloon flight, shielding his instruments from solar radiation by taking measurements during a near-total solar eclipse. Could he have also been reading reflected solar wind? It is granted the amount of reflected solar wind would be very low compared to direct solar wind, however, without knowing how much cosmic radiation there should be, it seems the reflected solar wind could significantly distort such a cosmic radiation measurement. These days we also know the Earth’s magnetic field is shielding us from the solar wind, as in the charged particles of it. However we are now taking space-based measurements of cosmic radiation, away from that shielding.
After reviewing this list of cosmic radiation experiments, I see some looking for larger nuclei, antimatter, and gamma rays, with the majority concentrated on high-energy cosmic radiation, thus low-energy solar wind seems excluded.
However after reading about energetic neutral atom (ENA) imaging and IBEX, it looks like this ribbon was detected with IBEX-Lo, with the solar wind creating ENA’s.
Can these reflected solar wind particles be accidentally counted as cosmic radiation, as may have happened in the past?
Can we detect the difference between the low-energy solar wind and low-energy cosmic radiation, if such exits?
If the amount of cosmic radiation was overwhelmingly large compared to solar wind, then this would not be an issue. But as it looks like the amount of cosmic radiation is small compared to solar wind, and merely being “in the shade” will not keep solar wind from being counted along with cosmic radiation when merely counting particles, it appears this reflected solar wind could be a matter of some concern.
vukcevic (11:00:52) :
Impossible!
Indeed
As I already mentioned : magnetic field is a three-dimensional while a line is an abstract mathematical two-dimensional entity. The second cannot represent the fundamental nature of the first.
This is nonsense as lines can be curved in three [or any number of] dimensions. But is also irrelevant for the discussion.
Have you now grasped that the HCS sweeps all over the sky all the time?
kadaka (11:18:06) :
How do I differentiate between the sources of particles?
cosmic rays move almost at the speed of light, while solar wind [reflected of not] move 1000 times slower. So, on average have a million times less energy. Cosmic rays are also much rarer than solar wind particles, so even is more energetic still only adds to a total energy less than 3% of that of the solar wind.
Leif Svalgaard (07:59:46) :
Evans (07:53:52) presented Professor Fitzpatrick’s quote as part of a longer passage from Dr. Fitzpatrick’s university lecture: “In conclusion, all magnetic fields encountered in nature are generated by circulating currents.”
Evans added in response to the Fitzpatrick quote and Dr. Peratt’s quote: “Perhaps the source of magnetic fields isn’t a mystery after all.”
Dr. Svalgaard asked a question: “What generates the current?” and stated: “And if you accept the Biermann battery mechanism there is no mystery.”
Answering, “what happened in the beginning,” type questions is fraught with uncertainty. In fact, somethings Man will never know with certainty.
In regards to the “Biermann battery” hypothesis alluded to by Dr. Svalgaard, it reminds me of a hypothetical where a body of plasma is gravitationally bound and motionless in space.
Enthropy will cause the plasma to dissipate away from the gravitationally bound body of plasma into the vacuum of space (from high pressure and temperature to low pressure and low temperature, “an equalization process”, this possibly could take the form of a toroidal outward spin away from the body of plasma.
This outward toroidal spin will cause in effect: “The moving plasma, i.e., charged particles flows, are currents that produce self-magnetic fields, however weak.” — A. L. Peratt
Of course, that is only a possible hypothetical and I welcome Dr. Svalgaard’s critique.
James F. Evans (12:12:02) :
Dr. Svalgaard asked a question: “What generates the current?” and stated: “And if you accept the Biermann battery mechanism there is no mystery.”
The Battery effect is just one [albeit a favored one] possibility. Sp needs no further elaboration [anyway google it and learn more]. Of more interest is my first question: ‘what generates the currents?’ and in realistic environments, e.g in the Galaxy.
Leif Svalgaard (12:01:16) :
“This is nonsense as lines can be curved in three [or any number of] dimensions. But is also irrelevant for the discussion.”
Yes, but that does not make them three-dimensional entities, which magnetic field is.
Line is a mathematical abstract and has only one dimension, the length. A curve, presumably you are referring to, canot enclose a space. For an entity to be tree-dimensional it must encompass a volume without a discontinuity. These are axioms, not someone’s opinion; science does not accept opinions in a preference to axioms. An open ended spiral (as a curved line) in space, is still one-dimensional entity. Möbius strip is a surface curved in three-dimensional space but it has only two dimensions (you can have lot of fun by cutting it with scissors along the central line, and along one 1/3 away from the edge). Altogether an idea difficult to grasp for those, as you said, “often do not appreciate this ‘flexibility of thought’ ”. I stray too far, so I conclude. Good night to all.
“To mislead” implies deliberate deceit;
“A misleading comment” implies one that leads the reader astray, perhaps, or even probably, inadvertently (because of incompleteness or lack of clarity);
“Your misleading comment” falls somewhere in between the two connotations above, but it’s closer to the second than the first, IMO.
Other words that imply wrongness without necessarily implying deceitfulness are “false” and “untrue,” but they’re also less fuzzy and thus more offensive.
vukcevic (13:09:26) :
Line is a mathematical abstract and has only one dimension, the length.
Completely irrelevant [as that would apply to straight lines]. When we talk about magnetic field lines, we, of course, talk about curved lines.
Now, you have gone quiet on the topic, in spite of my explicit questions. Here is a deal for you: I’ll spend some of my time educating you about the HCS and the Heliopause and the Ribbon. In order to ensure that you get each point, we’ll take small steps and each posting will be short and require a ‘yes’ or a ‘no’ as to whether you understood it. If ‘no’, then we drill deeper on the point where you have difficulties. If you do not wish to do this, I must take that as resistance to learning about this. This is a rare opportunity that should not be passed up. Got a deal?
Roger Knights (13:16:52) :
“A misleading comment” implies one that leads the reader astray, perhaps, or even probably, inadvertently (because of incompleteness or lack of clarity);
Well, Vuk never clarified what he meant, and didn’t answer my question. And I’m sure he would object to have been led astray!
Leif Svalgaard (12:09:25) :
cosmic rays move almost at the speed of light, while solar wind [reflected of not] move 1000 times slower. So, on average have a million times less energy. Cosmic rays are also much rarer than solar wind particles, so even is more energetic still only adds to a total energy less than 3% of that of the solar wind.
I had read on ENA detection that Time Of Flight was measured for both HENA’s and MENA’s. At close to the speed of light, that must be some very quick timing.
But for LENA’s at less than 1 keV, they are simply run through an ion spectrometer to see what they are. Thus at present, it does not look like they can distinguish between such LENA’s related to solar wind and those from cosmic radiation. Does cosmic radiation generate LENA’s with such low energy?
Oh, I’ve been glancing through the magnetism discussion. So a magnetic field in space does not “switch off” once the underlying current that generated it ends, once established it simply remains there until something “taps into” it, disturbing the field?
“Much remains unknown about the local ISM, (interstellar medium) including details of its distribution, its origin, and how it affects the Sun and the Earth. ”
http://antwrp.gsfc.nasa.gov/apod/ap020210.html
Great discussion!
Leif, the caltec image of the HCS shows a tilt relative to the orbital plane which your diagrams don’t. Is there a reason for that?
tallbloke (16:05:09) :
Leif, the caltec image of the HCS shows a tilt relative to the orbital plane which your diagrams don’t. Is there a reason for that?
Yes, it has to do with whether there at the moment of calculation were two [Caltec] or four [me] sectors present. Also with whether the ‘warps’ are of equal size. If of unequal size an spurious tilt is introduced in the inner solar system. In any case [2 or 4 sectors, equal or unequal sizes] once you move a bit further out the tilt completely disappear and the HCS is wound 30-50 times around the rotation axis. Here is a nice animation of almost 40 years of the current sheet base. Blue color is field away from the Sun, red is into the Sun. You can see how often the warps have different ‘sizes’.
tallbloke (16:05:09) :
i>Leif, the caltec image of the HCS shows a tilt relative to the orbital plane which your diagrams don’t. Is there a reason for that?
Here is another nice movie http://www.leif.org/research/HCS-Movie-hi.gif that shows the solar wind speed in a meridional cut through the solar system out to 15 AU. To good approximation the solar wind speed contours also outline the HCS [speed is lowest there]: Shown is the case for two sectors, so near the Sun you nicely see the HCS bobbing up and down like a tilted plane rotating. But as you get away from the Sun, the tilt disappears and the volume of space occupied by the HCS [the blue area] is not tilted at all, but stays nicely symmetric around the equatorial [‘orbital’] plane.
Leif Svalgaard (17:48:21) :
tallbloke (16:05:09) :
Here is a nice animation of almost 40 years of the current sheet base: forgot the link: http://www.leif.org/research/WSO-SS.gif
At the risk of going a little off-topic, here’s a little more why the Solar System’s journey through the interstellar cloud reminds me Poul Andersen’s book Brain Wave.
Couldn’t find out from the NASA web site how long the Sol has been moving through the interstellar medium and when it will get out. Nevertheless, the discovery puts Brain Wave’s basic fictional premise on scientifically more solid ground.
I’m surprised that nobody else mentioned this until now. It’s been weeks, y’know? Why, does no one read sci-fi classics anymore? 😉
sHx (18:10:46) :
Couldn’t find out from the NASA web site how long the Sol has been moving through the interstellar medium and when it will get out.
Old Sol has done this throughout its life and will never get out. The medium does vary a bit in density from time to time, though. As the Earth is DEEP inside the solar system [in the innermost 1/millionth of the volume] so we are pretty much screened from the antics of the Heliospheric interaction with the interstellar medium
Leif Svalgaard (18:17:44) :
Sir, thanks for the explanation. One does often lose the sight of the scale. But it raises another question. How is it that cosmic rays can cause any antics in the atmosphere, since the Earth is so far deep in the Solar System? I can only assume that’s because the interstellar medium consist of particles whereas cosmic rays, as the name implies, is light.
sHx (20:50:17) :
I can only assume that’s because the interstellar medium consist of particles whereas cosmic rays, as the name implies, is light.
The name is a misnomer. They are particles as well, but they have a million or more times the energy of solar wind particles. A single really energetic cosmic ‘ray’ can have the energy of a high-power rifle bullet or more. Luckily they are rare and the Earth’s surface is large. And it is not proven that cosmic rays do much to our climate although it is so claimed.