Can Planets Thrive in Binary Star Systems?

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Discussion Overview

The discussion revolves around the existence and stability of planetary orbits in binary star systems, exploring the dynamics of such systems and the potential for stable orbits despite the gravitational influences of multiple stars. Participants consider various orbital configurations and the implications for habitability.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Some participants propose that planets may orbit around the center of mass of the two stars, although there is uncertainty about the stability of such orbits.
  • Others argue that if planets are sufficiently close to one star, stable orbits can exist due to the limited disturbance from the other star, similar to the stability of Jupiter's moons.
  • A participant mentions the existence of stable orbits far from both stars, which may orbit around the center of mass of the binary system.
  • There is a question about the possibility of a "figure-eight" orbital pattern for a planet orbiting both stars, referencing a Wikipedia article that discusses the dynamical limitations of such orbits.
  • Another participant draws a parallel between the dynamics of binary star systems and the Earth-Moon system, noting that the Sun's gravitational influence does affect the Moon's orbit but does not destabilize it.
  • One participant clarifies that the stars in a binary system rotate around their common center of mass, which can vary based on their relative sizes.

Areas of Agreement / Disagreement

Participants express a range of views on the stability of planetary orbits in binary star systems, with no consensus reached on the specifics of orbital configurations or the implications for habitability.

Contextual Notes

Some claims about orbital stability depend on specific conditions and assumptions regarding the distances and masses of the stars involved, which are not fully resolved in the discussion.

lifeonmercury
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How can planets exist in star systems with two or three stars? Shouldn't the planets' orbits get severely disturbed by the other stars?
 
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Maybe the planets orbit around the center of mass of the two stars? Not certain though.
 
If the planets are close enough to one star or the other, then there are stable orbits because the disturbance from the other star is not enough to make the orbits unstable. Just like Jupiter's moons can orbit Jupiter without being disturbed by the sun. There are also stable orbits that are far from both stars and orbit around the center of mass of the two stars, like Comeback City said.
 
220px-Planets_in_binary_star_systems_-_P-_and_S-type.svg.png

https://en.wikipedia.org/wiki/Binary_star
Wikipedia says there are S-type and P-type orbitals. Could there possibly be an orbital where a planet orbits both stars, but in a "figure-eight"-type pattern?
 
Comeback City said:
Could there possibly be an orbital where a planet orbits both stars, but in a "figure-eight"-type pattern?
It seems like this quote from Wikipedia's Habitability of binary star systems article addresses this question:

In reality, some orbital ranges are impossible for dynamical reasons (the planet would be expelled from its orbit relatively quickly
 
lifeonmercury said:
How can planets exist in star systems with two or three stars? Shouldn't the planets' orbits get severely disturbed by the other stars?

How can Earth have Moon? Shouldn't Moon's orbit be severely disturbed by Sun?
It is. The Sun disturbs the eccentric orbit of Moon so severely as to turn it completely in less than 9 years.
The matter, however, is that the apsides of Moon's orbit precess through a full circle - while the actual eccentricity remains unchanged.
 
Actually the stars rotate about the center of the mass of both. The center of mass is a point on a straight line joining the centre of the stars.
upload_2017-2-7_16-11-14.png
One of the configurations is this. However the centre of mass varies, it could be near the bigger star even on the bigger one but still the other will rotate. In case of the moon and the earth:
upload_2017-2-7_16-15-1.png
This is what happens and this is also a cause for tides
 

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