An international team of scientists, led by astronomers from the University of Wisconsin-Madison, has recently conducted a groundbreaking study that sheds light on the gases surrounding young stars and how their mass evolves over time. By utilizing a network of 66 radio telescopes known as the Atacama Large Millimeter/submillimeter Array, positioned at an elevation of 16,000 feet in the Chilean Andes Mountains, the researchers examined the gas disks orbiting around 30 young stars.

Professor Ke 'Coco' Zhang, an astronomy expert at UW-Madison and the head of the ALMA Survey of Gas Evolution of Protoplanetary Disks, emphasized the importance of understanding the mass within these protoplanetary disks to determine the types and number of planets that can potentially form within a star system.

The study focused on stars ranging from less than 1 million years old to over 5 million years old, which are considered relatively young in the life cycle of a star. These stars are typically surrounded by protoplanetary disks composed of approximately 1% dust and 99% gas, predominantly hydrogen and helium.

Through careful analysis of the electromagnetic radiation emitted by the gas disks, the researchers were able to accurately measure the mass of various gas molecules. By tracking the intensity of the N 2 H+ ion signature, which becomes more prevalent as carbon monoxide diminishes, the team observed a rapid decline in gas mass within the first million years of protoplanetary disks, followed by a slower decrease over time.

While the formation of gas giants like Jupiter requires the presence of ample gas within the disk, the process of creating rocky planets can occur at a more gradual pace over hundreds of millions of years due to the persistent nature of dust particles. The study also suggests that gases lost from the disks may be expelled through a phenomenon known as disk wind, where gas molecules are accelerated out of their orbit by crossing magnetic field lines.

Future research will involve examining the chemical composition of the innermost regions of protoplanetary disks, where rocky planets such as Earth are believed to form. The James Webb Space Telescope will play a crucial role in this investigation, as it offers superior capabilities for studying hot materials in the inner disk region. By analyzing the evolution of materials like water and organics, researchers aim to gain a deeper understanding of how these elements change over time.

For more details on the ALMA Survey of Gas Evolution of Protoplanetary Disks, visit the National Radio Astronomy Observatory's website.

The study received funding from the National Science Foundation (2205617 and 2205870).