Astronomers Spy the Dynamics Behind a Triple Star System

Scientists have made the most accurate study so far of a cocoon of gas and dust surrounding a triple star system. Using complementary observations from multiple instruments, the researchers have identified the complex dynamics at work within the system, called GG Tau.

Recent observational discoveries have shown that there exist many planets orbiting double stars. Yet the formation of these planets has run up against the problem of gravitational instabilities caused by the binary nature of these stars. And until recently, GG Tau A was thought to be a binary system of two stars, Aa and Ab. Yet new measurements reveal that GG Tau A is actually a triple star system, GG Tau.

Using ALMA and IRAM in addition to the VLTI/ESO wavelengths, the scientists have already identified a rotating disc of gas and dust around this triple star system. As the three stars orbit one another, they create an unstable gravitational region called a cavity, through which matter can only travel before falling onto the central stars. Further away, the gravitational field is no longer disturbed, and the rotating matter can form a stable structure.

The scientists actually uncovered some of the dynamics surrounding the cavity. They found a stream of gas from the outer ring flowing toward the central stars. The amount of gas transported in this way is sufficient to feed the inner disc around GG Tau Aa. The observed motion of the gas also confirms predictions by earlier numerical simulations.

The findings reveal a bit more about the processes occurring when it comes to this triple star system. This, in turn, may reveal more information about other systems in the universe.

The findings are published in two papers in the journals Astronomy & Astrophysics and Nature.