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Message: <blockquote data-quote="Nyeshet" data-source="post: 5359558" data-attributes="member: 18363">This would be difficult to set up realistically. If the stars are closer than about 3 AUs (if I recall correctly), then they act as a single barycenter around which the planet orbits. They would appear as two suns that are always near each other - rising and setting together, etc. If the suns were further apart, there is a risk that the gravity of one would upset the orbits of the planets that tried to form about of the other (either preventing formation or tossing them out of the system during formation) unless they are *much* further apart - so far apart that the one not orbitted by the planet appears star-like (or - more accurately - venus-like, in apparent size in the sky). It would still give off as much light as a full moon, more or less, but it would not obviously be a second 'sun' - let alone provide enough heat for a hotter summer, etc.Edit: I found the link I was looking for: planet forming discs of dust do not seem to form in binary star systems that are between ~3 and ~50 AUs apart. The stars either have to be nearer than 3 AUs (and so act as a single star for orbital purposes) or farther apart than 50 AUs (in which case the second sun will appear star-like). <a href="http://solstation.com/habitable.htm" target="_blank">http://solstation.com/habitable.htm</a><a href="http://solstation.com/images/bi2sep.jpg" target="_blank">http://solstation.com/images/bi2sep.jpg</a>On the other hand, I have some little experience in working on the equations for luminosity of stars in such a system, as I once worked out what a red dwarf star (0.34 sol masses) at 108 AU away would look like from a planet at a mars like orbit (1.69 AUs) from the binary star (1.29 sol masses). The red dwarf would have a luminosity of about -11.7, compared to the full moon's luminosity of about -12.7 and the earth's sun's of -26.8. So it would be no larger than any given star in the night sky, but its brightness would be that of a gibbous moon. You will get some faint shadows from the reddish-star due to its brightness, but little else. If we presume a sun-like binary star companion at ~50 AUs, its brightness would likely be several times brighter than the full moon - but it still would be too faint to give any real extra heat to the world. Okay, I calculated by extrapolation the apparent luminosity of a sun-like G2 star at 50 AUs using the link below. It works out to -18.37. This is roughly equivalent to the brightness of the sun as seen from Pluto (-18.2) or Neptune (-19.3). Your red dwarf tidally-locked planet not get much heat from its second sun, but low light vision should see much farther than on an earth-like world, at least when the second 'sun' is in the night sky. Mythically, locals might view this second sun as instead the king of the stars, the local myth equivalent of Jupiter due to its brightness. <a href="http://www.johnbray.org.uk/planetdesigner/" target="_blank">http://www.johnbray.org.uk/planetdesigner/</a><a href="http://en.wikipedia.org/wiki/Apparent_luminosity" target="_blank">http://en.wikipedia.org/wiki/Apparent_luminosity</a></blockquote>

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