Wouldn't each system's star do a decent job of pushing back extra-solar radiation? Up to a point, obviously, but it would seem that planetary background radiation levels aren't a direct function of solar density.
My question was about the ability of a system's star's own radiation to ward off extra-solar radiation and what kind of limitations we are aware of.
Ha! I love straighforward sanity checks like this. My initial reaction was to ask myself about photon-photon collisions which are im fact possible, but your comment gives a nice Fermi bound on how rare such events actually are. Cool!
But yeah. Ionized particles like Galactic Cosmic Rays can be repelled by the local stellar magnetic field, but mostly the lower energy rays are deflected. Higher energy -to-charge-ratio GCRs can punch right through the weak stellar magnetic field, just like do for our Sun’s interplanetary magnetic field.
I knew low-energy waves are partially deflected, I just wasn't sure about high-energy waves. Makes sense!
I would expect mid-frequency radiation such as visible light to remain largely unaffected, I was thinking more about its effect on high-frequency extra-solar radiation. And it's likely not correct to visualize this as individual photons colliding but rather wave interference.
Here is an article explaining the effect [0]. An excerpt:
"The interplanetary magnetic field, which is embedded in the solar wind, deflects low-energy cosmic rays from us at the outer reaches of our solar system, decreasing the flux of these cosmic rays that reach us at Earth."
[0] https://aasnova.org/2017/12/01/a-shifting-shield-provides-pr...
The heliosphere does provide us with a significant amount of protect from cosmic rays, which aren't actually electromagnetic radiation. Cosmic rays are extremely energetic particles, typically protons, coming in from outside the solar system. The Earth's atmosphere also does a good job stopping cosmic rays, which means their primarily a hazard to spacecraft, both manned an unmanned. (I don't know what effect cosmic rays would ultimately have on Earth if we didn't have the protection of both the heliosphere and our own atmosphere, but I know they have been investigated for links to mass extinctions.) They're a threat to space travel because they cause soft errors in electronics, and DNA and other radiation damage to human beings.
The Sun's magnetic field - aka the interplanetary magnetic field or heliospheric magnetic field - travels with the solar wind and fills the solar system. It is magnetically coupled to solar system bodies like the Earth and Jupiter. As an amateur astronomer, the heliospheric magnetic field doesn't have any significant effects on photons coming into the solar system.
I don't think you understood my question very well because none of what you presented is new to me nor is it what I asked about. Still, thank you for the time and effort.
We have made it at least a billion or so without getting too close to a nasty body so that says something about the region around us.
It explores the possibility that general relativity could be discovered by a pre-industrial civilisation living inside an asteroid in a very tight orbit of one those nasty interlopers.