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The Earth and the Sun has magnetic fields which shields us from cosmic rays, as a charged cosmic ray particle will loose kinetic energy when its direction is perpendicular to the magnetic field. So what happens to the kinetic energy of the cosmic ray particle? According to the first law of thermodynamics it can't just disappear.

According to electro-mechanics it will induce an electric current. The particles also get a spiral motion and can induce a magnetic field like a current in a solenoid. Some radiation due to breaking of the particle (bremsstrahlung) may also occur.

The vast magnetic field of our sun is bombarded with cosmic rays with far bigger energy intensity than the cosmic rays that hit our shielded Earth. On Earth the most energetic cosmic ray observed is a subatomic particle with kinetic energy equal to that of a baseball (5 ounces or 142 grams) traveling at about 100 kilometers per hour (60 mph).

So I wonder if its a possibility that the Sun is partly powered by cosmic rays? How large can the total cosmic ray energy hitting the heliosphere be and where does the energy go?

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  • $\begingroup$ If cosmic rays could power the sun (they can't) then why wouldn't they also "power" the earth and burn us all to a crisp? See also: the Aurorae Borealis and Australis. Also the "most energetic cosmic ray" you refer to is a UHECR which is significantly different from what people normally refer to as a cosmic ray (galactic cosmic ray). $\endgroup$ – user21433 Mar 5 '14 at 14:58
  • $\begingroup$ @SeanD: I wouldn't say that they're significantly different, just the locations of the sources are significantly different (galactic sources vs extra-galactic sources). $\endgroup$ – Kyle Kanos Mar 5 '14 at 15:41
  • $\begingroup$ I would say that the salient differences are deflection due to the earth's magnetic field (huge Larmor radius) and even more importantly number flux. Also of course you have acceleration mechanism and composition (depending on which papers you read). $\endgroup$ – user21433 Mar 5 '14 at 15:48
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The Earth and the Sun has magnetic fields which shields us from cosmic rays, as a charged cosmic ray particle will loose kinetic energy when its direction is perpendicular to the magnetic field. So what happens to the kinetic energy of the cosmic ray particle? According to the first law of thermodynamics it can't just disappear.

It goes to the magnetic field.

According to electro-mechanics it will induce an electric current. The particles also get a spiral motion and can induce a magnetic field like a current in a solenoid. Some radiation due to breaking of the particle (bremsstrahlung) may also occur.

Yes, cosmic rays can generate a current and therefore a magnetic field (this is the idea behind magnetic field amplification (cf. this paper by M Bruggen (arXiv)). But note that roughly 90% of the cosmic rays we observe are protons which cannot generate bremsstrahlung radiation, it is the electrons that do this (roughly 9% of the cosmic rays).

The vast magnetic field of our sun is bombarded with cosmic rays with far bigger energy intensity than the cosmic rays that hit our shielded Earth. On Earth the most energetic cosmic ray observed is a subatomic particle with kinetic energy equal to that of a baseball (5 ounces or 142 grams) traveling at about 100 kilometers per hour (60 mph).

Do you have any sources for this claim in bold? We've seen some $\sim10^{18}$ eV cosmic rays on earth, which is pretty big. The largest one we've seen, which you mention, had an energy of $3\times10^{20}$ eV which is just insanely massive. We don't have great statistics in the ultra-high energy regime ($10^{15}$ eV and larger) because we get one particle per square-kilometer per century in that regime (fortunately we've had a fair number of square-kilometer arrays for a good many years, so we do have some).

So I wonder if its a possibility that the Sun is partly powered by cosmic rays?

The sun is powered by the active nuclear fusion (hydrogen burning) in its core. Cosmic rays are (theorized to be) produced in magnetic reconnection events on the sun's surface.

How large can the total cosmic ray energy hitting the heliosphere be and where does the energy go?

I would imagine that the largest energy cosmic ray that would hit the sun would be around the same as ours on earth. This energy would go into the sun. Note, though, that the sun produces roughly $10^{45}$ eV in energy per second through hydrogen fusion; adding $10^{20}$ eV is completely insignificant.

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    $\begingroup$ The heliosphere extends out beyond the orbits of the planets. The flux of galactic cosmic rays hitting the heliosphere is many times that at Earth or the Sun. The Voyager spacecraft have confirmed an greater flux of galactic cosmic rays. sciencemag.org/content/341/6142/150.full $\endgroup$ – DavePhD Mar 5 '14 at 15:21
  • $\begingroup$ @DavePhD: Oooh, flux not energetics, got it. (PS: well aware of that paper as my own research is on cosmic ray production) $\endgroup$ – Kyle Kanos Mar 5 '14 at 15:38
  • $\begingroup$ Thanks for a great answer! The magnetic field of the Heliossphere is huge, Voyager 1 is not yet out of the Solar magnetosphere and its 19.000.000.000 kilometers away from the Sun and its aimed at the bulge of the magnetossphere where the magnetic field is thinnest. The solar magnetotail could again be hundreds of times longer if it behaves like the magnetosphere of planets. Then again we don't know because we haven't observed the intergalactic wind which drags the magneto-tail out. $\endgroup$ – Enos Oye Mar 6 '14 at 12:11
  • $\begingroup$ @KyleKanos Yes the Voyager 1 has confirmed that there is a rise in cosmic ray flux at the outskirts of the magnetosphere. So nice that you have a cosmic ray theory, I have also a cosmic ray hypothesis, I posted it as a question: physics.stackexchange.com/questions/61830/… In this question you also find a graph which show Voyager's measured increased cosmic ray count. Magnetic reconnection is also a fascinating topic, do you have a link to your research? $\endgroup$ – Enos Oye Mar 6 '14 at 12:31
  • $\begingroup$ @EnosOye: My research is more on the production of GCRs at their source (supernova remnants) and not on the transport or solar production. I haven't yet published (my code is on a cluster), so I can't link anything. $\endgroup$ – Kyle Kanos Mar 6 '14 at 13:43

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