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Tech to change star type?

Posted: Mon Oct 02, 2017 4:33 pm
by Oberlus
Looking at the new black hole star that "lights up" my now-dark human home-world system (had to do it because my empire needs solar hulls and its a Young Galaxy with no natural blackholes in sight), I thought "if I can turn a red star into an small and under-control black hole, why can't I force a star to grow and be more bright, or the opposite?".

This is the only reference to "change star type" since early 2014 (I gave up searching on older threads):

From http://www.freeorion.org/forum/viewtopi ... 411#p87411
labgnome wrote:Changing star-type used to be a thing you could unlock tech to do, perhaps re-introducing it? FYI: I also plan on giving them a work-over, along with self-sustaining in conjunction with my planned tech-overhaul as well.
I guess (if that was a tech) that it was like Terraforming but for a star, and actually more like the collapse-red-star-into-a-blackhole tech.
I would make it way more expensive than Terraforming.

Is there a reason for having removed such tech from the game? I assume balancing issues with phototrophic species?

Re: Tech to change star type?

Posted: Tue Oct 03, 2017 8:53 am
by Vezzra
Oberlus wrote:Is there a reason for having removed such tech from the game?
I can't remember that there has ever been such a tech in the game.
I assume balancing issues with phototrophic species?
I'd expect that to be a problem, if such a tech were introduced.

Re: Tech to change star type?

Posted: Tue Oct 03, 2017 2:42 pm
by MatGB
It was there, Solar Accelerator IIRC, it was removed either before or at the same time as different metabolisms were introduced, back when everyone was human the ability to turn your homeworld star blue didn't matter, now it might be just a little unbalanced for certain species.

I think we could balance it if we wanted to revisit it, but I'm not sure the work involved in balancing it would be worth it: on the other hand, having a growth tech or two specifically for phototrophes is something I have in mind if/when we split up growth techs a bit.

Re: Tech to change star type?

Posted: Mon Oct 09, 2017 11:42 am
by Jaumito
What's the rationale for the red-stars-only requisite for artificial black holes, by the way? Methinks that shorter-lived, more massive blues or whites should be better candidates.

Re: Tech to change star type?

Posted: Mon Oct 09, 2017 12:51 pm
by MatGB
Jaumito wrote:What's the rationale for the red-stars-only requisite for artificial black holes, by the way? Methinks that shorter-lived, more massive blues or whites should be better candidates.
No idea, I found when it was added
-Commented out Solar Rejuvination tech and added a red star location … · freeorion/freeorion@5915cd4
Geoff committed it but the patch was by someone no longer contributing: ultimately, it doesn't really matter that much for realism purposes, and for balance purposes I think it's better it's at the 'worst' star type that can't otherwise be an energy yard: if you could easily upgrade your blue star energy shipyard to making solar hulls that'd make those beasts way to easy to construct.

(their temporary nerf can probably go now but I haven't time to test it ATM)

ETA: that's also the same commit that removed the star type changing effects, find the discussion about that and you've got the reasons: back then all changes came through the forum and had to be committed by one of the maintainers.

Re: Tech to change star type?

Posted: Mon Oct 09, 2017 2:54 pm
by Jaumito
MatGB wrote: [...] ultimately, it doesn't really matter that much for realism purposes, and for balance purposes I think it's better it's at the 'worst' star type that can't otherwise be an energy yard
Oh, I'm fully aware of that (realism should never trump gameplay and/or balance), and note that I was only asking for a rationale, not requesting a game change. :wink:

Speaking of rationales, the only "realistic" (note the quotes) ways I can think of to articially create a black hole from an existing star, would be to either -
  1. speed up the stellar nucleosynthesis a lot, i.e. making the star burn faster, quickly leading to its explosion and collapse (it would also probably destroy every planet in the system)
  2. find a way to suppress the nucleosynthesis entirely, causing an instant collapse
Either way, you'd want mass enough for the final collapse to give birth to a black hole, and the mass-luminosity relation suggests main-sequence "red" stars would be the worst choices for either scenario. Even worse, their longer lifespan would also get in the way for scenario (1)

Re: Tech to change star type?

Posted: Mon Oct 09, 2017 3:42 pm
by Geoff the Medio
I thought red stars were supposed to be red giants?

I may misremember the discussion though, and couldnt find a relevant thread...

Re: Tech to change star type?

Posted: Mon Oct 09, 2017 4:53 pm
by Jaumito
Geoff the Medio wrote:I thought red stars were supposed to be red giants?
Aha. I assumed a "red star" in FO meant what's otherwise called a red dwarf, since (1) these stars are quite common, and (2) their longevity means they're even more abundant in old galaxies, compared to their brighter brethren - which can exhaust their fuel 100 or 1000 times faster.

A red giant, on the other hand, is just a transitional phase in the life of a main sequence star. Since that phase lasts only a fraction of the star's lifespan, they're a whole lot rarer than "red dwarves". Hence my implicit assumption.

Re: Tech to change star type?

Posted: Mon Oct 09, 2017 4:59 pm
by Oberlus
As for wikipedia, there are blue, yellow and red hypergiant stars, as well as other sizes.

Re: Tech to change star type?

Posted: Mon Oct 09, 2017 5:29 pm
by Jaumito
Oberlus wrote:As for wikipedia, there are blue, yellow and red hypergiant stars, as well as other sizes.
They're also extremely rare. Like, we've found only a few dozens red hypergiants so far, among billions of stars. I wouldn't expect them to be your average "red star" in FO. :wink:

Re: Tech to change star type?

Posted: Mon Oct 09, 2017 8:16 pm
by MatGB
Always remember: the entire galaxy was made by the Experimentors in as an evil experiment.

Organic life orbiting black holes can happen, unusual star frequencies is absolutely fine ;-)

Re: Tech to change star type?

Posted: Mon Oct 09, 2017 9:15 pm
by Jaumito
MatGB wrote:Always remember: the entire galaxy was made by the Experimentors in as an evil experiment.
:lol:
Organic life orbiting black holes can happen, unusual star frequencies is absolutely fine ;-)
Actually, if that black hole is rotating and has a fat gas giant in close enough orbit, it could feed off of it - and the resulting accretion disk could theoretically generate more than enough light for life to appear on more distant planets. Sorry, but if you're looking for examples of Experimentors' bizarre interferences with "rational" science, try something... weirder. :P

Re: Tech to change star type?

Posted: Tue Oct 10, 2017 7:11 am
by Oberlus
Jaumito wrote:They're also extremely rare. Like, we've found only a few dozens red hypergiants so far, among billions of stars. I wouldn't expect them to be your average "red star" in FO. :wink:
Yeah, they are not average red star, nor blue or yellow red star. I meant just that the color is not what makes them appropriate to form a blackhole, but the size (if I'm not wrong) which is more or less independent of the color.

Re: Tech to change star type?

Posted: Tue Oct 10, 2017 9:43 am
by Jaumito
Oberlus wrote:I meant just that the color is not what makes them appropriate to form a blackhole, but the size (if I'm not wrong) which is more or less independent of the color.
Rather less than more, then. Of course there are exceptions to this rule (e.g., evolved stars like super/hypergiants or stellar remnants), but for main-sequence stars at least (i.e., the "normal" ones), there's a pretty direct relation between mass and "color", as seen in the chart below. Note that it fits FreeOrion's own classification (and the phototrophic "habitability equation" as well) rather nicely.
stellar-classification-0.png
stellar-classification-0.png (53.23 KiB) Viewed 1983 times

Re: Tech to change star type?

Posted: Tue Oct 10, 2017 10:01 am
by Geoff the Medio
Jaumito wrote:Of course there are exceptions to this rule (e.g., evolved stars like super/hypergiants or stellar remnants), but for main-sequence stars at least (i.e., the "normal" ones), there's a pretty direct relation between mass and "color", as seen in the chart below.
Considering the entire Hertzsprung–Russell diagram shows less clear correlation, however...

https://en.wikipedia.org/wiki/Hertzspru ... arData.png