JWST Finds Planet Formation Is a Race Against Time in 72 Young Star Systems

Using the James Webb Space Telescope (JWST), astronomers have studied 72 young, sun-like stars to investigate how protoplanetary disks lose material. The research reveals that forming planets is a real race against time, as the building blocks for planets are constantly escaping the swirling platters of gas and dust that wrap around infant stars.

James Webb Space Telescope Observes 72 Young Stars

The investigation represents the most in-depth study yet into how matter escapes these protoplanetary disks and how this escape gives rise to different stages of planet formation around sun-like stars. According to UA.News, the findings help paint a better picture of how and why our solar system took the shape it did around the infant sun approximately 4.6 billion years ago.

Tracking Molecular Hydrogen and Disk Evolution

The team conducted its research using data collected by the JWST’s Mid-Infrared Instrument (MIRI). Scientists tracked matter loss by following the movements of molecular hydrogen, which is one of the most common molecules found in protoplanetary disks.

Each of the 72 stars involved in the investigation represented a different stage in the early life of a star system. By putting these snapshots together, researchers created a sequence detailing the early evolution of a planetary system. One of the key findings is that mechanisms for material loss from protoplanetary disks evolve and switch dominance as an infant star ages.

Shifting Mechanisms of Mass Loss

At the early stages of protoplanetary disk evolution, mass loss is mainly driven by powerful, magnetically-infused jets and winds. These magnetic fields permeate the disks around young stars. Later, as the disk thins and starlight passes through it more easily, those winds and jets weaken, and magnetic processes are overtaken by high-energy radiation from the infant star ionizing gas and blowing it into space, a process called photoevaporation.

What is exciting about this study is that we can now see, across a large sample of young systems, how the mechanisms that remove gas from planet-forming disks change with time, team member Uma Gorti from the SETI Institute said in a statement.

The Race Against Time for Gas Giants

The research demonstrates that no single process is responsible for stripping planet-forming material from around infant stars. Different types of planets may find their formation windows closing sooner than others because disk dispersal sets a fundamental clock for planet formation.

Gas giants like Jupiter must assemble their massive atmospheres while the disk is still substantial enough to supply them, before winds and jets carry that raw material away into space, team leader Naman Bajaj from the University of Arizona said in a statement. Uma Gorti added that once the gas is gone, the opportunity to build gas-rich planets is essentially over.

Next Steps and Publication

The research demonstrates that the JWST is capable of studying the dispersal of gas and dust around individual infant stars. Moving forward, the team aims to discover how much material these different mechanisms shift and to identify the specific regions of the disks where they operate.

Ultimately, this work will help develop a model to reveal how rapidly planet formation is shut off and in which regions different types of planets are most likely to form. The team’s findings were published in The Astronomical Journal.