Colliding two Sols causes Supernova

[Dominian]

Okay, so I take our sun and place another sun right next to it. They start colliding as intended, but then they both blow up in a supernova. ( repeated this three times to be certain)

I'm not the biggest expert in theoretical physics, but that's insane. Any star going supernova would need to be 8-10 times more massive than our Sun.

So I went ahead and made the sun x10 havier. BOOM, it went supernova instantly. Where is the entire process of expansion and time ellapsing before the sudden collapse causing the supernova?

Funny enough, if you put a star with 0.1 times the mass of the Sun into the Sun, you get a spectacular impact, but still no merging. In fact the impact causes the Sun to lose mass.

So what's up with that? Why don't the stars merge, if they are clearly below the mass it takes to create a supernova?

Are there other considerations like speed of impact? If I just place them within each other they explode, if I let them collide 'gently' they explode just aswell.

So I went ahead and tried to create a Type 1A Supernova. That's a white dwarf gathering mass from a second star in its system until it's about 1.4 times the mass of the Sun and then goes BOOM in a thermonuclear explosion. We use these as standard candles to measure distances, so it's basic stuff.

Of course it didn't work. The white dwarf passes the bigger main sequence star and compltely annihilates it. If you collide two white dwarves on the other hand, you get a supernova.

What the hell is happening here? Am I just using a game about planets wrong, by focusing on the stars?

[bshapiroalbert]

Thanks for asking about this. The short answer is that our current star simulation is rather old and we don't yet simulate stellar evolution in Universe Sandbox. We are planning to update our star simulation in the future and add basic stellar evolution, but that's a fairly large project that will involve some complex physics and major updates to our simulation so we don't have a timeline for it yet.

The more complicated answer is that it depends, but we also don't have a lot of data on what happens when two main sequence stars merge since it doesn't happen very often. You're absolutely correct that stars that explode naturally in supernovas at the end of their lives are at least 8 solar masses.

However it is thought that if two main sequence stars collide, they will result in something called a Luminous Red Nova. Not as intense as a supernova, but still quite bright and similar in appearance. In Universe Sandbox we don't yet differentiate between different types of supernova or other nova. Since we don't simulate stellar evolution yet, there's not a lot of reason to add that yet.
https://en.wikipedia.org/wiki/Luminous_red_nova

Currently we determine if two stars merging explode in a supernova based on how much the stars overlap before merging and the mass of the impacting star. Essentially if there's lots of overlap between the two stars and their relative mass ratios are large, they explode. This is something we want to improve when we get around to updating our star simulation.

We're also aware of an issue where stellar remnants are not being left behind correctly when large stars explode that's on our to-fix list.

[Dominian]

Thanks for the quick and thorough answer and especially for teaching me about the Luminous Red Nova.

I really appreciate the level of communication you show on these forums and what has already been implemented.