How planets form around binary stars

Washington D.C.: A team of researchers has used Atacama Large Millimeter/submillimeter Array (ALMA) to give out details about the very early stages of planet formation around a binary star.

Embedded in the outer reaches of a double star's protoplanetary disk, the researchers discovered a striking crescent-shape region of dust that is conspicuously devoid of gas. This result provides fresh insights into the planet-forming potential of a binary system.

Astronomers struggle to understand how planets form in binary star systems. Early models suggested that the gravitational tug-of-war between two stellar bodies would send young planets into eccentric orbits, possibly ejecting them completely from their home system or sending them crashing into their stars. Observational evidence, however, reveals that planets do indeed form and maintain surprisingly stable orbits around double stars.

To better understand how such systems form and evolve, astronomers using the ALMA took a new, detailed look at the planet-forming disk around HD 142527, a binary star about 450 light-years from Earth in a cluster of young stars known as the Scorpius-Centaurus Association.

This binary system has long been known to harbor a planet-forming corona of dust and gas, said Rice University's Andrea Isella, adding that the new ALMA images reveal previously unseen details about the physical processes that regulate the formation of planets around this and perhaps many other binary systems.

By studying a wide range of protoplanetary disks, astronomers hope to better understand the conditions that set the stage for planet formation across the Universe.

The study has been presented at the AAAS meeting in Washington, D.C.