
Although recent observational discoveries have shown the existence of many planets orbiting double stars, their formation ran up against the problem of the gravitational instabilities caused by the binary nature of such stars.. Observations of young binary stars are still too scarce to provide a detailed picture of these processes. Until very recently, GG Tau A, located 450 light years from Earth in the constellation Taurus, was thought to be a binary system of two stars, Aa and Ab. However, recent infrared measurements carried out with the VLT and VLTI (ESO) instruments have shown that GG Tau A is in fact a triple star system: GG Tau Ab is itself a binary star. The central star Aa is far enough away from the Ab pair for it to be surrounded by a circumstellar disc, first observed in 2011 with the IRAM interferometer.
Around this triple star system the researchers have already identified a rotating disc of gas and dust, whose center is cleared by gravitational tidal effects. As the three stars orbit around 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, where the outer ring of matter is located, the gravitational field is no longer disturbed, and the rotating matter can form a stable structure. The existence of a central cavity around GG Tau A, known since the 1990s thanks to observations with the IRAM interferometer, partially confirmed these theoretical predictions. In the 2000s, the presence of gas in the cavity was detected, but the precise dynamics of this gas, which is the key to understanding the accretion mechanisms giving rise to planets, remained largely unknown.












Comment: It appears as if nothing is safe anymore.