Here is map of the IBEX energetic neutral atom (ENA) flux projected on the sky in an Aitoff-Hammer projection (Wikipedia: Aitoff, Wikipedia: Hammer). The map is projected so the 'nose' of the Sun's motion through the interstellar medium, is at the center of the plot. This map is projected as 'unwrapping' the sky around the Sun. An animation illustrating how the sky is 'unwrapped' to create this projection is available at "IBEX First Skymap Release". In this map, red color corresponds to maximum atom fluxes of up to 300 energetic neutral atoms per square centimeter per second per steradian (a measure of angular area on the sky) per kiloelectron volt for particles with energies between 0.9 to 1.5 kiloelectron volts. The minimum values in blue and violet correspond to fluxes less than 100 atoms in the same units. The maximum flux in the 'ribbon', the bright colored feature stretching across roughly the center of the map, is brighter than the background by a factor of about two or three.
With this press release, a mechanism has been proposed which seems to explain the IBEX ribbon feature. As I suggested in "IBEX Results Cause Even More Problems for the Electric Sun Model", an explanation would most likely be found in more detailed consideration of the particle kinetics, and this mechanism certainly fits that description. The mechanism provides a simple explanation why the ribbon appears where the interstellar magnetic field is perpendicular to the line-of-sight.
The graphic below is based on Figure 2 in the paper and illustrates the mechanism. It considers the possible trajectories of two protons from the solar wind moving through the heliosphere. One proton scatters off the interstellar magnetic field (ISMF) and continues outward, not being detected by IBEX (violet path). The other proton scatters off the ISMF and is essentially 'reflected' back towards the inner solar system where it can be detected by IBEX (green path). In this graphic, various regions are labeled:
TS = termination shock (about 80 AUs from the Sun)
IHS = Inner heliosheath
OHS = Outer heliosheath
HP = Heliopause
This process happen in multiple steps. The red dots along the violet and green trajectories indicates points where ionization (loss of an electron, yielding a positively charged ion) or electron capture (gain of an electron by an ion resulting in a neutral atom) occurs with other particles in the region. The dotted portion of the trajectories indicate where the atom is actually an ion:
1) The solar wind carries hydrogen ions (H+) out from the Sun and they penetrate the termination shock (TS) into the inner heliosheath (IHS). The magnetic field carried in the solar wind does not strongly influence the trajectories of these ions.
2) In the IHS, they can charge-exchange an electron with the ambient neutral atoms, becoming an energetic neutral atom (ENA). This interaction could result in a slight alteration of the ENAs trajectory due to energy-momentum conservation.
3) Once electrically neutral, the ENA travels in a straight line, uninfluenced by the local magnetic fields. The ENA easily penetrates the heliopause into the outer heliosheath (OHS), where it encounters the interstellar magnetic field.
4) With another charge exchange with ambient plasma, the ENA becomes a pick-up ion (PUI) and is influenced by the interstellar magnetic field (ISMF).
5) The PUI gyrates in the magnetic field. The gyro-radius for the particle energies and ISMF strength has a mean value of about 12,000 kilometers. The density is sufficiently low that the timescale for the PUI to capture an electron and be converted back into an ENA is about two years.
6) The PUI eventually captures an electron and is freed from the magnetic field, proceeding off in the direction at the time of electron capture.
The process is surprising simple. But the really interesting part is what happens depending on the direction of the solar wind ion with respect to the ISMF direction. The violet trajectory crosses the ISMF at an angle that gives it a large velocity component parallel to the ISMF. But the green trajectory crosses the ISMF with a small velocity component parallel to the ISMF. This means the PUIs on the violet trajectory can travel a long way from the heliopause before it becomes an ENA again. Meanwhile, the PUI on the green trajectory, with its much lower speed parallel to the magnetic field, will only travel a short distance before becoming an ENA again. Essentially, the ENAs on the green trajectory get 'stored' for a time, by gyrating in the magnetic field. Once neutralized to an ENA, there is a probability that some of the ENAs will be thrown back from the direction they came, where they have an increased probability of being detected by IBEX.
The authors of the paper simulated this process, constructed a skymap using the same projection as the IBEX data, which demonstrates the enhancement.
Here again is an example of how real science deals with problems. Researchers present their model of the process in a form that can be analyzed mathematically. This makes it easier for other researchers to critique, duplicate, and extend the analysis. Is the IBEX ribbon solved? I don't know. But this analysis demonstrates that the problem is not fatal to the standard stellar models as the various pseudo-scientists try to promote it to be.
I suspect the Electric Sun (ES) advocates will continue to spin the IBEX result as a victory for their claims of the Sun and stars being powered by cosmic-scale external electric currents. They will, as always, have nothing but 'stories' and/or 'cartoons' to support their claims and nothing that matches any actual measurements or models that can be rigorously tested.
Will we ever see something like this from the Electric Sun supporters in a form that can be objectively reproduced by other researchers?
It's not impossible, but I'm not holding my breath.
Special thanks to Jacob Heerikhuisen (University of Alabama, Huntsville) for corrections and helpful comments.
1 comment:
Some of the image links broke so those have been fixed.
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