Question re binary star systems

[Kate_C]

Stargazers Lounge community,

The sci-fi novel I wrote takes place in a binary star system and I'm attempting to fact check before handing over to my agent. From what I gather, there are S-type, P-type & T-type systems, but I'm having a hard time wrapping my mind around the orbital possibilities. Hoping someone's expertise can help! Would it be theoretically possible to have a planet in a binary star system where there is a daily "pre-sunrise" and a "pre (or post) sunset" due to the dimmer star? And could there be daily syzygy with the stars or might it need to be less frequent? If anyone can advise or has any suggestions, it would be so appreciated! Thank you!

[cloudsweeper]

Kate - an interesting (and no doubt very complex) question, for which I can't often you much I'm afraid.  A great many binaries have huge separations - many hundreds of AUs (1 AU is the Sun-Earth separation; Pluto is about 40 AU from the Sun).  Now a planet in such a system, being of relatively small mass, would orbit one of the stars rather than the common centre of mass, so I would guess the other star would be shall we say much less noticeable on the planet.

However, I imagine you are referring to close pairs with orbital periods of days or hours, so each star would come into and out of view on the planet in a complex (but predictable) way depending on many parameters.  

Many scenarios might therefore be possible, and it would be impossible to contradict them unless all the physical properties of the system were specified and your readers are all astrophysicists!  

Hope the novel does well!

Doug.

 

[Corncrake]

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Edited July 20, 2020 by Corncrake

[Sunshine]

If you are referring to a binary system whereby one of the stars has a planet, then i would expect that syzygy would occur quite frequently. Exactly what time scales (intervals) syzygy would occur would depend on how far the two stars are apart and, the distance of the planet from its parent star, more often in a binary where stars are closer to each other. There are sooooo many variables involved and, as mentioned above, unless the exact physical distances, masses, planes, etc are known, no one can argue against almost any scenario you choose. Regarding the pre sunrise/sunset, i imagine a planet with a tilt whereby the dimmer star just barely grazes the horizon as seen from the surface of the planet. Imagine the dimmer star never rises above the horizon and, always appears as a daily sunset/sunrise before the parent star actually rises and tracks across the sky (as our sun does). Whoa!! my mind melts, there are just too many variables, i think its safe to say that you can pretty much rest assured that no one will poke holes in your novel, unless, you are actually describing a known system who's physical properties are already understood.

I would really like to know what this novel will be titled, i would love to read it. 

Best of luck!