Say a planet was in orbit around one star in a binary star system. . . Would it be possible at all, for the distance between the stars and the distance from the planet to each star to be sufficient so that the planet could evolve life?
Say the planet's days and years were equal to Earth's based on the star its orbiting.. Could the planet always be in a position so that its Sun would be between the planet and the other star? Or would it never have true night since there's always another sun...?

I know these are peculiar questions, but I'm really interested in the answers

Thanks!

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~Lunaorion~
Every Airplane Dives Gracefully Before Exploding

Hi Lunaorion,

There would always be a "night" (or at least a part where the sun doesn't shine) on that planet (whether it is rotating or not).

There are only a few possible situations:

1) The planet orbits both the stars, then there's obviously one unlit part (the one opposing the suns)

2) The planet orbits one of the two stars: then there's only a "night" when the planet is not between the two stars (since there's always an unlit part there too).

The evolving of life is a difficult question since it depends on many factors (is there water on the planet? - this also means that the planet has to be close enough to the sun(s), but not close enough to evaporate - are the temperatures more or less suitable for certain chemical reactions to start, ...). The orbit of the planet has to be almost circle-shaped (otherwise the temperature variations are too great), etc etc...

Bye!

Crisp

--
"The best thing you can become in life is yourself" -- M. Eyskens.

Recently, there's been some news that indicates coronal mass ejections can be spurred by entanglement of massive magnetic fields from mutually-orbiting bodies. In the case of two orbiting stars, we have enormous magnetic fields being tangled up on enormous scales. I would imagine that in such systems, massive coronal mass ejections from both stars happen on a regular basis. This would severely and frequently irradiate any planets in such a system, even the planets with relatively strong magnetic fields, such as Earth. This would have implications on evolution of life. Either life would be confined to underground and underwater environments, or it would evolve high tolerance towards high-energy radiation...

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I am; therefore I think.

Boris,

Essh. In that case, can I change the situation slightly? What if one of the stars was just the quite dead, and was only a corpse of a star? Not so much that it collapsed into a neutron star or something interesting like that, but just ran out of hydrogen and went through the swelling and contracting motions till it just fizzed out.
I know they have a name, but it escapes me.



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~Lunaorion~
Every Airplane Dives Gracefully Before Exploding

The name is "white dwarf". That's what the Sun is going to become at the end of its life. Obviously, such things happen only <u>very</u> late in the life of a solar system. Moreover, prior to becoming a white dwarf, the star goes through a red giant phase, followed by a nova. The nova would likely sterilize the entire region of space around the star. And, by the time a star becomes a white dwarf, the entire system in general is very old. If life was going to evolve in this system, chances are it already did so even before one of the stars grew old.

Boris,

Hmm... Not a white dwarf, those still shine weakly, no? I found an article that mentions what I mean, a brown dwarf <a href="http://zebu.uoregon.edu/~soper/StarLife/browndwarfsS.html">(here).
In fact, since many low mass stars are made, one would expect many wanna-be stars to be formed. A catchy name for them is brown
dwarfs. Where are they? They are not so easy to find. They should glow for a while from the conversion of gravitational potential energy to heat. Then their light output should fade away.

Unfortunatly I didn't find a time scale for this to occur on in this article...




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~Lunaorion~
Every Airplane Dives Gracefully Before Exploding

That's different, but not that much different. What threw me off was your reference to a "corpse" of a star. Brown dwarfs are not corpses, because no star "died" to make them; rather they are like miscarried fetuses that never materialized into a full-fledged star.

Either way, should the binary system contain both stars close to the center, the massive flares remain a problem. Even a brown dwarf sports an enormous magneic field. For example, Jupiter is far from being a brown dwarf, but even it has the most powerful magnetic field in the solar system after the Sun. The same problems would exist for any systems where a very massive planet closely orbits the star (like in most of the recently-discovered extrasolar systems.) This means that most of the extrasolar planetary systems we have discovered are probably poor nurseries of life.

On the other hand, as I said life could potentially evolve along different lines than on Earth. For example, it's possible life could evolve within such "hazardous" environments under thick cloud covers, under water or under ground. It's also possible that life could evolve tolerance for radiation. For example, bacteria exist on Earth that thrive inside the highly-radioactive cooling rods of nuclear reactors.

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I am; therefore I think.