17 The Atacama Large Millimeter/ submillimeter Array (ALMA) is located on the Chajnantor plains in Chile, nearly 16,000 feet (5,000 meters) above sea level. Image courtesy NRAO/AUI/NSF Other techniques for finding baby planets in the disks surrounding young stars are based on observations of the emission coming from a disk’s dust particles. But dust only accounts for 1% of a disk’s mass, so the team decided to focus instead on the gas that comprises 99% of a young disk. Their new technique focuses on the motion of the gas, probing radial pressure gradients in the gas to see the shape of the perturbations—like swirls and eddies—allowing astronomers to make a more-precise determination of the masses and locations of planets embedded in the disk. Their new method successfully confirmed the previously predicted existence of two Jupiter-mass planets around HD 163296. They orbit at distances of 83 and 137 times the distance between the Sun and the Earth, but the host star is much brighter than the Sun. “Although dust plays an important role in planet formation and provides us invaluable information, it is the gas that accounts for 99% of protoplanetary disks’ mass. It is therefore crucial to study kinematics, or motion, of the gas to better understand what is happening in the disks we observe,” explained Bae. “This method will provide essential evidence to help interpret the high-resolution dust images coming from ALMA. Also, by detecting planets at this young stage we have the best opportunity yet to test how their atmospheres are formed and what molecules are delivered in this process,” said lead author Teague.  Jaehan Bae has been the Rubin Postdoctoral Fellow at Terrestrial Magnetism since September 2017. Image courtesy Roberto Molar Candanosa