Planets in binary star systems

In summary: Summary:In summary, the planets can exist in star systems with two or three stars if the planets orbit around the center of mass of the two stars. If the planets are close enough to one star or the other, then there are stable orbits. However, the center of mass of the two stars can vary, so the planets may be near the bigger star on the bigger one but still the other will rotate. This can cause tides.
  • #1
lifeonmercury
137
26
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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  • #2
Maybe the planets orbit around the center of mass of the two stars? Not certain though.
 
  • #3
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.
 
  • #4
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?
 
  • #5
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
 
  • #6
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.
 
  • #7
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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Related to Planets in binary star systems

1. Can planets exist in binary star systems?

Yes, planets can exist in binary star systems. In fact, many planets have been discovered in binary star systems, including the famous Tatooine planet from the Star Wars franchise.

2. How do planets form in binary star systems?

The formation of planets in binary star systems is similar to that in single star systems. The two stars in the system can either form independently or from the same molecular cloud. As the stars begin to form, their gravitational pull can cause material to clump together, eventually forming into planets.

3. Are the orbits of planets in binary star systems stable?

The stability of planetary orbits in binary star systems depends on a variety of factors, including the mass and distance of the stars, as well as the size and position of the planet. In some cases, planets in binary star systems can have stable orbits, while in others, their orbits can be disrupted by the gravitational pull of the stars.

4. Can planets in binary star systems have habitable conditions?

Yes, it is possible for planets in binary star systems to have habitable conditions. However, this depends on various factors such as the distance from the stars, the type of stars, and the composition of the planet's atmosphere. Some binary star systems have been found to have potentially habitable planets, such as the Kepler-47 system.

5. Are there any differences in the characteristics of planets in binary star systems compared to those in single star systems?

There can be some differences in the characteristics of planets in binary star systems compared to those in single star systems. For example, the presence of two stars in the system can affect the amount of heat and light received by the planet, potentially altering its climate and atmosphere. Additionally, the gravitational pull of the stars can also affect the planet's orbit and rotation.

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