Stellar Lifecycles

[Evil_Tom]

Hello,

This is my first post here, and I must say I'm enjoying playing with US2 quite a bit so far!

I recently opened and ran the Sun lifecycle simulation and have also tried this with other stars in my own simulations.

I set the stars to realistic and I'll use the Sun as an example here.
The Sun ages and expands with all the side effects that has, but once it reaches a certain size it then instantly turns into a Sun nova remnant. I have a few questions/comments at this point.
This size is not as large as I would have expected (ie: radius of up to 1AU). I thought the Sun would turn into a red giant first, or is this not simulated?
The change from Sun to Sun nova remnant is sudden. Is there not a nebula formed by this expansion? I would've expected a gentle (in stellar/nova terms) expulsion of the outer layers of the sun as gravity loses to temperature/pressure.
Also after this initial transition into nova remnant the cycle just goes through an infinite loop of cooling and shrinking and then expanding suddenly. The numbers in the cycle always remain the same. I guess there will be fits and starts as gravity and pressure fight over the dying star, reigniting the fusion at different pressures and temperatures, but there is no different in density or mass of the star beyond this point. Only radius and temperature change with age of as stellar remnant. Would it not be prudent to simulate mass loss (which appears at 0 in the dynamic tabs) for a remnant?

I really wanted to see the quiet and slow death of our beloved Sun over the eons, but instead it appears to be stuck in an endless loop.

[Jenn]

The nova remnant issue is a bug to do with the fact that our lookup tables drop off after a certain age, and I am working on fixing that now.
A non-bug issue that we need to figure out how to deal with, which is probably what you experienced, is how to adapt time steps when people are trying to observe stellar evolution or other similar varying time-scale events. The sun does become a red giant, but not for very long, it eventually becomes a planetary nebula + white dwarf. When you speed up time to watch the sun heat up most users speed up time so much that they miss the red giant stage. I would like to maybe force timesteps to slow down when major events occur so that people don't miss them.

[Arian]

@jenn
Maybe just have the "pause on collision" option extended to a dropdown field that lets you pause on (sudden) changes in certain properties of an object (maybe with a threshold).

@Evil_Tom
I think the mass loss value refers only to evaporation, so it doesn't really apply to stars.