The abnormal orbit of the TF planet - an attempt to find explanation.

GreyW · May 12, 2015

The system Bleae Thua DS-A d14-4 with a single star of F0 V was discovered a gas giant with three satellites TF. The orbit of the giant 7 AU. Accordingly orbit satellites ~~0.1 AU~~ refined - 3ly = 0.006 AU
Question- how the satellites receive heat sufficient to become candidates for terraforming?
This is a bug, or maybe there are certain factors that the topic starter is not taken into consideration?
Thanks to Google for translation.)

Murishani · May 12, 2015

Beautiful system.

F stars are hotter than our sun and the heat would reach farther, also if I'm not mistaken, a gas giant can produce it's own heat from gravitational compression, maybe a combination of heat from the giants in the system and the F star is enough to keep the giants moons warm?

GreyW · May 12, 2015

I am inclined to the same opinion.

Jackie Silver · May 12, 2015

That is strange. Blackbody temperature at that distance for that star is around 140 degrees Kelvin.

That's far lower than the usual requirement for terraformables (about 223K to 315K blackbody) and also lower than the coldest water world I've seen (about 150K blackbody.)

The satellites may get some heat off the gas giant if they're close but it shouldn't be enough to push them into the terraformable range.

For some systems (generally hand-coded ones like HIP stars) there is a bug of sorts where the temperatures are higher than they should be but your system doesn't look like one of those.

Do have a look at my Hab-zone calculator if you're interested in this stuff - if you have a look at the source code included in the zip you can see such information as I have on temperature ranges and so on.

adoredtv · May 12, 2015

I don't believe multiple objects (at least stars) affect the habitable zone in a system otherwise we'd see a lot more habitable stuff much further out.

Murishani · May 12, 2015

Jackie Silver said:
The satellites may get some heat off the gas giant if they're close but it shouldn't be enough to push them into the terraformable range.

they are only 0.006 AU away so they're fairly close.

hey Jackie, would the presence of that many gas giants in system do anything to warm it up? There are seven of the things. Also regarding the bug, maybe it actually is a hand coded system for some reason?

Jackie Silver · May 12, 2015

Murishani said:
they are only 0.006 AU away so they're fairly close.

hey Jackie, would the presence of that many gas giants in system do anything to warm it up? There are seven of the things. Also regarding the bug, maybe it actually is a hand coded system for some reason?

Oh, I missed that - at such a short distance then maybe it is the gas giant. Gimme a little while to work it out.

Jackie Silver · May 12, 2015

Ah yes. That's probably it. I make the blackbody temperature of a rock at that distance from the gas giant (if it was floating in deep space) to be 114K. The temperature at that distance from the star is 140K as above. Now, in real life you wouldn't just add the two numbers together, but Elite does some funny things when it comes to calculating the temperatures of planets and in this case I think it does, giving a total 254K which is within the habitable range.

The reality is that in equilibrium the heat input from all sources (the flux at a certain distance from the source is absorbed across a cross section of the planet; this is summed for all sources) balances the heat output (given by Stefan-Boltzmann law) - in some circumstances Elite does this, in others, it just adds up the temperatures. Makes life interesting trying to model it, and then there are the handcoded systems where it all goes out the window anyway!

I hadn't previously looked at how gas giants are treated, only at stars, but now we know...

Murishani · May 12, 2015

Jackie Silver said:
in some circumstances Elite does this, in others, it just adds up the temperatures.

In which systems does it calculate it properly, just hand made ones?
Perhaps the procedural generator just add the temperatures to avoid more complex math and says "close enough"?

Jackie Silver · May 12, 2015

Murishani said:
In which systems does it calculate it properly, just hand made ones?
Perhaps the procedural generator just add the temperatures to avoid more complex math and says "close enough"?

There are two different issues:

1) Some stars (handcoded) are treated as being much hotter than they really are. IIRR a good indication that this will be the case is if you find a main sequence star whose spectrum is given as plain "V" (and not "VA", "VB", "VAB") it's likely to be wrong. My suspicion is that the handplaced stars were generated using a broken algorithm (with planetary albedo given the wrong sign) which was later fixed for the bulk of the procgen stars but was too much hassle to redo all the handplaced ones.

2) For all star systems, handcoded or not, the temperature of a planet at a certain point should not simply be the sum of all the individual blackbody temperatures it would have from different sources. If planet Alicia orbits a star like the Sun at 1 au and planet Bobbit orbits a very close binary pair of Sun like stars at 1 au, Bobbit will not be twice as hot as Alicia. It'll be hotter, but not twice as hot. And so on. In Elite, this is modelled ok for binary pairs, but not for other stars in the system - if you have distant stars in the system, their temperature contributions are added. It thoroughly confused me when I was trying to model it!

The upshot is that for all the single-star, procgenned systems and many of the binaries out there in the galaxy, everything works exactly as it should.