I am not an astrophysicist but...

DukeIronHand

D
This seems to be the hang out for our ships Science Officers so it seems like a good place to ask.

Out exploring and I come across systems with multiple suns.
Sometimes (to the eye anyway) they seem very close together. Is this realistic?

Seems that gravity would pull them together...to presumably destabilize and go (super)nova or "blow up" or something?

See other smaller odd things that I can at least attach some pseudo-scientific reason for it but I really wonder about the suns being so close.

Anyone want to play Mr. Spock here?
 

Jackie Silver

Jackie Silver
DukeIronHand said:
Out exploring and I come across systems with multiple suns.
Sometimes (to the eye anyway) they seem very close together. Is this realistic?
Click to expand...

Yes. You can get stable binaries close enough that they're touching (contact binaries.)

Seems that gravity would pull them together...to presumably destabilize and go (super)nova or "blow up" or something?
Click to expand...

That doesn't happen because they're orbiting. If they weren't already moving with respect to each other, then yes, gravity would bring them together. Because they're already moving sideways past each other, gravity tries to bring them together but only keeps them moving in orbit around their common centre of mass. Same way that the moon doesn't fall onto the Earth and the Earth doesn't fall onto the sun.

The game doesn't model the interesting deformations and visual effects we should see with close and contact binaries. It would be nice to see some time!
 
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CMDR AKIRA MASAKARI

CMDR AKIRA MASAKARI
DukeIronHand said:
This seems to be the hang out for our ships Science Officers so it seems like a good place to ask.

Out exploring and I come across systems with multiple suns.
Sometimes (to the eye anyway) they seem very close together. Is this realistic?

Seems that gravity would pull them together...to presumably destabilize and go (super)nova or "blow up" or something?

See other smaller odd things that I can at least attach some pseudo-scientific reason for it but I really wonder about the suns being so close.

Anyone want to play Mr. Spock here?
Click to expand...

I play mister Spock even tough I'm not astrophysician too. Stars that are very close and of similar mass should orbit themself really fast, acquiring potato shaped form, and probably they'd loose material having a "tail".
Eventually, but it can take several millions years, they should orbit closer and closer to the point they collide, making an huge explosion, shredding vast quantity of their outher layers, and eventually forming a third star that's the result of the collision of the former two.

At least that's what i saw in a documentary.

In the game they seems more static, but they are not static at all. Everything orbits, but in vast majority of occasion it takes a time it seems they are still to the naked eye. If you leave your ship in a system and come back after several hjours you'll notice that some fast m,oving object have changed position relatively to the ship quite drastically.

We could use a more dynamic galaxy with colliding stars and exploding supernovas, but these event seems quite rare and follow cycles that last hundred millions years. So putting too many would feel fake too.

A supernova explosion or two stars colliding doesn't happen any day, and the game is in real time. If they want to implement such features, it could be realistic they are studied by the majority of scientist and these events are well advertized on the Gal Net journal.
 

newman1702

newman1702
It depends on how close they are and what size / mass stars, etc, but close binaries do happen out there. Gravity wouldn't necessarily pull them together as long as they are in stable orbit of each other (there is an invisible point between the two that represents the center of mass of both stars combined, which both stars will be orbiting in this case as long as they have the velocity to maintain said orbit). Another thing to remember is that you are dealing with huge objects here, so what seems close to you is still actually pretty far, much further than, say, the Moon is from the Earth in a lot of cases.

Now, if the stars are very close, and one has much higher gravity than the other, it can "suck away" the other star's outer layers, and basically start scooping the other star's mass. What will happen to the other star depends on it's mass / stellar classification, but not every star is a nova or a supernova candidate, it needs to fill certain criteria (our own sun, for example, doesn't meet those criteria and will never go supernova).

With binaries it's more common for stars to go nova than supernova - one of the stars evolves more quickly (the larger, hotter one that burns it's fuel faster, typically) and turns into a white dwarf. It having a higher gravity than the other star, it starts to scoop up it's hydrogen, and the white dwarf's pressure and temperature make fusion reaction possible once again, now supplied with the other star's hydrogen. When enough hydrogen is collected, the outer layers explode in a fusion reaction, spreading stellar gas around. After this the cycle typically begins again and is repeated every x amount of years, depending on the stars in question (but we're talking very large amounts of time, as with anything in astronomy).
 
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CMDR AKIRA MASAKARI

CMDR AKIRA MASAKARI
Jackie Silver said:
Yes. You can get stable binaries close enough that they're touching (contact binaries.)



That doesn't happen because they're orbiting. If they weren't already moving with respect to each other, then yes, gravity would bring them together. Because they're already moving sideways past each other, gravity tries to bring them together but only keeps them moving in orbit around their common centre of mass. Same way that the moon doesn't fall onto the Earth and the Earth doesn't fall onto the sun.

The game doesn't model the interesting deformations and visual effects we should see with close and contact binaries. It would be nice to see some time!
Click to expand...

newman1702 said:
It depends on how close they are and what size / mass stars, etc, but close binaries do happen out there. Gravity wouldn't necessarily pull them together as long as they are in stable orbit of each other (there is an invisible point between the two that represents the center of mass of both stars combined, which both stars will be orbiting in this case as long as they have the velocity to maintain said orbit). Another thing to remember is that you are dealing with huge objects here, so what seems close to you is still actually pretty far, much further than, say, the Moon is from the Earth in a lot of cases.

Now, if the stars are very close, and one has much higher gravity than the other, it can "suck away" the other star's outer layers, and basically start scooping the other star's mass. What will happen to the other star depends on it's mass / stellar classification, but not every star is a nova or a supernova candidate, it needs to fill certain criteria (our own sun, for example, doesn't meet those criteria and will never go supernova).

With binaries it's more common for stars to go nova than supernova - one of the stars evolves more quickly (the larger, hotter one that burns it's fuel faster, typically) and turns into a white dwarf. It having a higher gravity than the other star, it starts to scoop up it's hydrogen, and the white dwarf's pressure and temperature make fusion reaction possible once again, now supplied with the other star's hydrogen. When enough hydrogen is collected, the outer layers explode in a fusion reaction, spreading stellar gas around. After this the cycle typically begins again and is repeated every x amount of years, depending on the stars in question (but we're talking very large amounts of time, as with anything in astronomy).
Click to expand...

That's the difference between watching documentries and studying stuff...
If I were you, I'd believe the other guys and not me.
 

CMDR Murf

CMDR Murf
Jackie Silver said:
The game doesn't model the interesting deformations and visual effects we should see with close and contact binaries. It would be nice to see some time!
Click to expand...

Especially with stars of different colors, like these:

Screenshot-Original.png


Would be interesting to see it with non-sequence stars too. All kinds of weird combos can be made.
 

DeRane

D
There are some things that I personally disagree with game physics.

Close trinaries in other words binary with close third star is one of the things that rises my eyebrow. The orbital periods are fixed, ie. depending on distance of center of orbit, right? So unless the third star is far orbiter, out there orbiting a center of mass of binary system, the whole system becomes unstable and thus chaotic and short lived (one of the binaries and third system particle start affecting each others orbits). The instability is temporary in astronomical level, pretty much meaning millions of years instead of hours, but finding multiple billion year old systems with third star or even another binary in few hundred Ls away is not really supported by physics in my view.

But I do have a question as well. I keep finding planets with hydrogen and helium atmospheres, often under 3G gravity. Is this realistic? I know Earth can not contain those gases in the atmosphere since they are too light and simply bleed away into space. What is the minimum gravity to hold on to light gases?
 

iain666

iain666
I've not noticed Hydrogen or Helium atmospheres. Gas giants report their composition as "atmosphere" and that's normally a hydrogen/helium mix - and smaller ones don't have massive surface gravity - but that's not quite the same thing as an atmosphere that's gravitationally bound to the surface of a rocky planet.
 

[VR] optimal_909

[VR] optimal_909
Jackie Silver said:
It would be nice to see some time!
Click to expand...

That was mentioned the last time David made an AMA, so I guess it'll come! :)

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DeRane said:
There are some things that I personally disagree with game physics.

Close trinaries in other words binary with close third star is one of the things that rises my eyebrow. The orbital periods are fixed, ie. depending on distance of center of orbit, right? So unless the third star is far orbiter, out there orbiting a center of mass of binary system, the whole system becomes unstable and thus chaotic and short lived (one of the binaries and third system particle start affecting each others orbits). The instability is temporary in astronomical level, pretty much meaning millions of years instead of hours, but finding multiple billion year old systems with third star or even another binary in few hundred Ls away is not really supported by physics in my view.

But I do have a question as well. I keep finding planets with hydrogen and helium atmospheres, often under 3G gravity. Is this realistic? I know Earth can not contain those gases in the atmosphere since they are too light and simply bleed away into space. What is the minimum gravity to hold on to light gases?
Click to expand...

It probably depends on the solar wind as well, in quite places perhaps lower g is enough to hang on the light gases.
 
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Amoebic

Amoebic
I don't believe stars can actually touch each others "surfaces" but they can share a single atmosphere.

After doing some extra research I concluded there are 3 types of binaries:

Detached binaries are your most common, they orbit each other from a larger distance and usually evolve apart from each other.

Semidetached binaries are closer stars where one is much larger than the other and takes the smaller bodies atmosphere.

Contact binaries are two similar sized stars close enough to each other to share their atmosphere. These are the ones that you should be talking about. (and fear)
 

Galactic Fork

Galactic Fork
Algol is an interesting example. It's a real system with a close binary pair only about 30ls apart and a third star another 1300 ls away from them. One thing is it's hard to tell how far apart stars are in the game just by sight. A star can take up the whole screen and you could still be 5 to 10 ls from it. In game, Algol looks like this:

JxA8OTk.jpg
 

Kabu

Kabu
There are a couple of other things that are unrealistic or poorly represented in Elite. Nebulas aren't as bright as we see them in the game nor can be seen from the inside, at least not with those amazing views we have in the game. Same goes for the Milky Way, not as bright in real life. Earth-likes in Core regions cannot exist because of radiation. You would see some weird things during Supercruice because you are going beyond the speed of light but due to gameplay they don't simulate it, same reason because laser beams are seen as luminus large ray instead of a dot in the enemy ship. Other things as stars bulging at the poles and accretion disk are, sadly, not implemented but they'll probably will in the future.
 
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