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Author Topic: Any star beyond 11.5 solar masses instantly explodes  (Read 2591 times)

SyzygyΣE

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Any star beyond 11.5 solar masses instantly explodes
« on: January 08, 2017, 08:53:11 PM »
This is the most bizarre issue I have ever encountered in US2.

When I attempt to increase any star's mass, once they reach about 11.5 solar masses, the star explodes in a supernova. It doesn't matter if I up the mass of a known star or a random main sequence star, the critical point is always around 11.5 solar masses.

Any star placed down has an assigned age. Therefore, I have suspected that this effect may be because a preexisting star's age is already too old for such giant stars to theoretically exist. But even when I set a star's age to 0 years and then increase its mass from this point onwards, it still cannot grow more massive than 11.5 solar masses.

I have also attempted different ways of increasing a star's mass, from plugging in numbers in the body tab to launching material at it. But again, no matter how mass is added, it always explodes once reaching 11.5 solar masses.

A star such as R136a1—which is far beyond 11.5 solar masses—doesn't instantly explode when I place it down, but it does do so if I switch off and then switch on the "Radius From Composition" button.

In fact, this issue only occurs if the option "Radius From Composition" is switched on. If switched off, stars can pass this point. R136a1 is an example of this. However, once this option is switched off, luminosity, temperature, density and radius are no longer simulated past 11.5 solar masses. Before 11.5 solar masses, all these parameters are proportional with each other even with "Radius From Composition" switched off, but do not change at all after this point with it switched off. While it is true that I could just create more massive stars with "Radius From Composition" off without having to worry about them exploding, I feel as if the parameters would not be proportional to each other or realistic if I manually plugged them in.

I find this issue rather strange and I'm not too sure whether it really is a bug. I don't recall anything out of the ordinary occurring to stars at this mass in real life, so I am fairly sure that this is not an accurate simulation of what is meant to happen. In real life, can't giant stars grow to over 11.5 solar masses without exploding, given that its fuel isn't exhausted yet?

This issue is quite easy to replicate. To do so, place down any random star under 11.5 solar masses, set its age to 0, ensure "Radius From Composition" is turned on, and then up its mass through any means. A supernova event should occur at 11.5 solar masses. To supplement this, I have included a video of the replication process.

If anyone has further information regarding this phenomena willing to share, thank you in advance for your assistance.

Replication Video
« Last Edit: January 09, 2017, 03:51:45 PM by SyzygyΣE »

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Re: Any star beyond around 11.5 solar masses instantly explodes
« Reply #1 on: January 09, 2017, 03:23:47 AM »
I don't seem to experience the same problem, think I've got it set up right, I started out with Polaris at 4.5 suns and pushed it up to 160 suns without it going supernova.  See what you think:



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SyzygyΣE

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Re: Any star beyond around 11.5 solar masses instantly explodes
« Reply #2 on: January 09, 2017, 04:05:42 AM »
I don't seem to experience the same problem, think I've got it set up right, I started out with Polaris at 4.5 suns and pushed it up to 160 suns without it going supernova.  See what you think:


I tested with Polaris, but unfortunately it still doesn't allow me to increase it past that mass. Although, something looks a bit odd with your star's parameters. "Radius From Composition" was switched on when you upped its mass, yes? Your Polaris' radius, surface temperature and luminosity are the same as the default 4.5 solar mass Polaris. When you increased its mass, the star's radius, temperature and luminosity all stayed the same. Those three parameters should have changed with any adjustment in mass. In my case, if I add onto a star's mass, its radius, temperature and luminosity all change.

This time I managed to get Polaris to 11.7 solar masses before it went supernova. But you can clearly see that its radius, temperature and luminosity have changed and are in proportion to any change in mass. I am confused why yours stayed the same despite increasing the mass so much.

Have you tried flipping the "Radius From Composition" switch off and on for that star and seeing if it explodes?
« Last Edit: January 09, 2017, 04:22:56 AM by SyzygyΣE »

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Re: Any star beyond 11.5 solar masses instantly explodes
« Reply #3 on: January 09, 2017, 09:21:56 AM »
When I switch "Radius From Composition" off then on again, I get this:

https://www.youtube.com/watch?v=AvsoN8uSmGA&feature=youtu.be

I then tried to get Polaris to die naturally, but couldn't.  Here's a shot of it more than 1 million G/Years old:



I started afresh, altered nothing but the age, It's still running and is now at 500 million G/Years+.   ???

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SyzygyΣE

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Re: Any star beyond 11.5 solar masses instantly explodes
« Reply #4 on: January 09, 2017, 03:14:52 PM »
When I switch "Radius From Composition" off then on again, I get this:

https://www.youtube.com/watch?v=AvsoN8uSmGA&feature=youtu.be

I then tried to get Polaris to die naturally, but couldn't.  Here's a shot of it more than 1 million G/Years old:



I started afresh, altered nothing but the age, It's still running and is now at 500 million G/Years+.   ???
Apparently, for the ageing process to apply to stars spawned in, you must first switch off and then switch on "Radius From Composition." From how I see it, preexisting stars are "locked." They are made a certain way so that their parameters will not be affected from timewarp unless you first toggle the button. If that doesn't fix it, this is probably not a shared issue between us. I don't want to duplicate my response but this is also what I would tell you in the other thread you raised: http://universesandbox.com/forum/index.php/topic,17128.0.html.

And in that video, the issue you encountered is exactly the same as what I have encountered. Get a star larger than 11.5 solar masses. Switch off and switch on the button. Then it goes boom. I'll see if I can get a video up to show you exactly how I'm replicating this issue.
« Last Edit: January 09, 2017, 03:31:53 PM by SyzygyΣE »

SyzygyΣE

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Re: Any star beyond 11.5 solar masses instantly explodes
« Reply #5 on: January 09, 2017, 03:52:54 PM »
Alright, the replication video is up. If you do the same as this video, you should be able to experience the issue.

Replication Video

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Re: Any star beyond 11.5 solar masses instantly explodes
« Reply #6 on: January 10, 2017, 04:53:06 AM »
Yes I get the same result as in your video every time. 

Thanks for trying to help with my immortal stars issue, but switching off and on RFC doesn't seem to help.
It's quite frustrating really, I just want to watch our sun expand then die, is that so much to ask?  ;)

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SyzygyΣE

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Re: Any star beyond 11.5 solar masses instantly explodes
« Reply #7 on: January 10, 2017, 07:10:53 AM »
Yes I get the same result as in your video every time. 

Thanks for trying to help with my immortal stars issue, but switching off and on RFC doesn't seem to help.
It's quite frustrating really, I just want to watch our sun expand then die, is that so much to ask?  ;)
I will perform some tests with timewarp on stars in regards to that immortal star issue and report my findings to you on the other thread.

In other news, I have made a discovery. The mass of the supernova remnants of these 11.5 solar mass stars is a little over the Chandrasekhar limit. White dwarfs will go supernova once reaching 1.39 solar masses, while these remnant cores are about 1.4 solar masses. I am unsure whether this is merely a coincidence, but for the first time, I'm actually getting figures that aren't just random and without pattern. This is a correlation. It doesn't really make sense and I can't explain how this number has anything to do with the star exploding, but nonetheless it is a correlation with something.

I am afraid I cannot test much further beyond this point. I have exhausted every possibility to counter this issue or find its root and nothing too convincing has come of it. If I discover something else in relation to this issue, I will report it on this thread.

Again, if anyone has any information regarding this problem willing to share, please do so.