Twin stars can wreck planetary systems

Tuesday, 8 January 2013 - 4:18pm IST | Agency: IANS
Planetary systems with distant binary stars are particularly vulnerable to cataclysmic upheaval, especially when they have them orbiting each other tightly, according to US astrophysicists.

Planetary systems with distant binary stars are particularly vulnerable to cataclysmic upheaval, especially when they have them orbiting each other tightly, according to US astrophysicists.

For instance, think of the consequences when at least one of our giant planets would likely be ejected if the sun had a companion star, says a team of Northwestern University's researchers.

Researchers found that wide binary stars in planetary systems can lead to dramatic events over time. In one hypothetical system, they added a wide binary companion to the Earth's solar system.

This triggered at least one of four giant planets' (Jupiter, Saturn, Uranus and Neptune) ejection in almost half of the simulations, the journal Nature reports.

Unlike the Sun, many stars are members of binary star systems -- where two stars orbit one another -- and these stars' planetary systems can be altered by the gravity of their companion binary stars, which themselves can be affected by other forces.

Nathan Kaib, from Northwestern, conducted 3,000 computer simulations to study the effects of binary stellar companions (some with tight orbits around each other and others with wide or distant orbits) on the formation and evolution of planetary systems, according to a Northwestern statement.

In the computer models, these ejections typically were delayed by billions of years, so the planetary systems would spend the first parts of their lives feeling no effects from the binary stars. Only after binary orbits became very eccentric did they catastrophically disrupt the planetary systems.

The astrophysicists also found substantial evidence that this process occurs regularly in known extrasolar planetary systems. These findings were scheduled for presentation at the 221st meeting of the American Astronomical Society January 6-10 in Long Beach, California.




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