Timeline for Do solar energetic particles follow the Parker spiral?
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| May 13 at 16:54 | comment | added | Outis Nemo | @LuKas: Yeah, I'm aware of that, although Alfvén in his later days stressed that the frozen-in flux theorem shouldn't be relied too heavily upon: "Later in life, Alfvén advised against the use of his own theorem." But in this case I agree, it's likely due to higher-order effects indeed, just wondered if you or someone else perhaps had a clear understanding of it, but I understand that it's not your specialty. | |
| May 13 at 11:49 | comment | added | Lu Kas | @OutisNemo ok, cool. I wasn't aware of this. But in general you need to keep in mind that a plasma system is terribly coupled: the plasma motion drives the magnetic field, and the magnetic field drives the plasma motion. To the first order, the Parker spiral is created by the motion of the plasma, with the magnetic field 'frozen-in' it. But when you get more complicated effects where plasma structures are blocked by others, as in your reference, you'll get higher order effects. And then certainly the magnetic field, which is along the Parker spiral, is going to affect the motion of the plasma. | |
| May 11 at 21:55 | comment | added | Outis Nemo | @LuKas: Those are separate effects, but there are many papers talking about a continuous deflection in the direction of the Parker spiral, all the way to 1 au and beyond, so much so that the total deflection can be as much as 30°+ at 1 au. The Parker spiral is explicitly mentioned as the reason: "Under the effect of the Parker spiral magnetic field, a fast CME will be blocked by the background solar wind ahead and deflected to the east, whereas a slow CME will be pushed by the following background solar wind and deflected to the west." (shorturl.at/apPU2) | |
| May 10 at 17:50 | comment | added | Lu Kas | @OutisNemo, that's a quite specific field of research that isn't mine. But how I understand it, this is thought to be caused by magnetic structures near the eruption region and occurs mostly relatively close to the sun, where the magnetic forces from the corona are still stronger. I've not really seen the Parker Spiral be said to be the cause. | |
| May 10 at 12:39 | comment | added | Outis Nemo | @LuKas: That's a good explanation; but how come fast CMEs are deflected "eastward" (in the reverse Solar physics convention of east and west, i.e. to the left as seen from Earth)? In papers about the deflection of CMEs it says that this occurs due to the Parker spiral. | |
| Mar 22, 2021 at 11:10 | comment | added | Lu Kas | The solar wind does not follow the Parker spiral. The solar wind moves radially outward from the Sun. It is the magnetic field that is connected to both this plasma in the solar wind and the location on the Sun's surface it was emitted from. Since the emitted plasma stays at the same angle, but the Sun rotates, the magnetic field forms a spiral. See it as spraying a water hose and twirling around. The stream of water you spray will create a spiral, but that does not mean the water travels in a direction following the spiral, it just moves radially outwards. | |
| Mar 16, 2021 at 14:34 | answer | added | honeste_vivere | timeline score: 2 | |
| Mar 16, 2021 at 14:11 | history | edited | honeste_vivere |
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| Jun 4, 2019 at 15:11 | comment | added | honeste_vivere | No, not in general or even necessary. So far as we can tell, there seems to be a lot of cross-field diffusion and much the inner heliosphere fills up with SEPs during strong solar flares. | |
| Jun 4, 2019 at 11:14 | comment | added | binaryfunt | @honeste_vivere I'm slightly confused by your last sentence, "not along the IMF". Did you mean "along the IMF"? If SEP enhancement is detected on the opposite side of the Sun, isn't that along the IMF (spiral wrapping around)? | |
| Jun 4, 2019 at 7:04 | comment | added | honeste_vivere | SEPs during strong flares actually fill up the inner heliosphere and do not necessarily follow the nominal interplanetary magnetic field (IMF) along what is usually consistent with the Parker spiral. However, the SEPs that do follow the magnetic tend to arrive earlier than those diffusing across the field. Some of the STEREO spacecraft observations show SEP enhancements on the opposite side of the sun from the flare source location, which is not along the IMF. | |
| Jun 3, 2019 at 15:39 | history | asked | binaryfunt | CC BY-SA 4.0 |