Using the ALMA observatory, scientists studying the protoplanetary disk around the young star HD 169142 found strong chemical evidence for the existence of a protoplanet and proposed a new method for detecting and studying these celestial bodies. The discovery of silicon monosulfide, indicative of a gas giant protoplanet, provides new insights into protoplanetary chemistry.

Scientists using the Atacama Large Millimeter/submillimeter Array (ALMA) to study the protoplanetary disk around a young star have found the most convincing chemical evidence of protoplanet formation to date. The discovery will provide astronomers with an alternative method to detect and characterize protoplanetaries when direct observation or imaging is not possible. Results will be published in the next issue. Astrophysical Journal Letters.

HD 169142 is a young star in the constellation Sagittarius that is of great interest to astronomers because of its large, gas- and dust-rich stellar encircling disk that is visible almost straight ahead. Several candidate protoplanes have been identified over the past decade, and earlier this year scientists from the University of Liège and Monash University confirmed that one such candidate, HD 169142b, is in fact a giant Jupiter-like protoplanet.

The discoveries from a new analysis of archival data from ALMA, an international collaboration involving the National Science Foundation’s National Radio Astronomy Observatory (NRAO), may now make it easier for scientists to detect, confirm and ultimately characterize protoplanetaries. formed around young stars.

Center for Astrophysics | Harvard & Smithsonian and lead author of the new study. “We now have confirmation that we can use chemical signatures to find out what types of planets may form in disks around young stars.”

The team focused on the HD 169142 system because they believed the presence of the giant protoplanet HD 169142 b would likely be accompanied by discernible chemical signatures, and they were right. Lowe’s team discovered carbon monoxide (actually ¹² CO and its isotopologue ¹³ CO) and sulfur monoxide (SO), previously detected and thought to be related to protoplanetaries in other discs.

But the team also discovered silicon monosulfide (SiS) for the first time. This came as a surprise because for SiS emission to be detected by ALMA, silicates must be released from nearby dust particles in large shock waves driven by gas moving at high speeds, typically from vents driven by giant proto-planets.

“SiS is a molecule we’ve never seen before in a protoplanetary disk, let alone around a giant protoplanet,” Lo said. “Detection of SiS emission has become obvious to us because it means this protoplanet produces powerful shock waves in the surrounding gas.”

With this new chemical approach to detecting young protoplanetaries, scientists can open a new window into the universe and deepen our understanding of exoplanets. Protoplanets, particularly those embedded in major extrastellar disks such as the HD 169142 system, provide a direct link to the known population of exoplanets.

“There is a wide variety of exoplanets, and using the chemical signatures observed with ALMA gives us a new way to understand how different protoplanetaries evolved over time and ultimately relate their properties to those of exoplanetary systems,” Lo said.

“In addition to creating a new tool for planet hunting with ALMA, this discovery unlocks a lot of exciting chemistry we’ve never seen before. As we continue to explore more disks around young stars, we will inevitably find other interesting but unexpected molecules like SiS. This type of The discoveries mean we’re only scratching the surface of the true chemical diversity associated with protoplanetary environments.” Source