Or in more imaginable terms: 9 solar radii out at the closest passes in the far future. Here's an older sim clip showing the process, https://www.youtube.com/watch?v=IClNiZ2-ee4
I have no clue how large the sun is, for all I know it could be 0.000001AU or 0.01AU, but I do know how hot the sun can be at 1AU and that Mercury is scorched at 0.21AU so that's a lot more imaginable than a multiple of some unknown unit, particularly "in the far future" (sounds to me like 10k years, but given the topic of a single mission, maybe it's 30 years? Or 10? This is super vague, too.)
Yes, that's the kind of thinking that resonates with me as an astronomer, and when I talk to the general public and non-astronomer scientists, I find that a lot more people have a grasp of how hot it is at 1/5 of Mercury's orbit than 9X the radius of the Sun.
My understanding is that AU is measured from the center of the sun / object. Google tells me that the radius of the sun is ~0.0046AU (1/215th of an AU).
