Protoplanetary disks lose their gas quicker than dust, reveals study
What's the story
A recent study conducted by an international team of astronomers has revealed that the disks of gas and dust surrounding young stars, lose their gaseous components faster than their dusty ones.
The groundbreaking findings were made using the Atacama Large Millimeter/submillimeter Array (ALMA) and were published in a dozen papers in a special issue of the Astrophysical Journal.
Survey details
Research a part of AGE-PRO program
The research is part of a large ALMA program called the ALMA Survey of Gas Evolution of PROtoplanetary Disks (AGE-PRO).
The survey looked at 30 planet-forming disks around Sun-like stars to measure how their gas disk mass changes with age.
Previously, ALMA observations have mostly focused on the evolution of dust in these disks.
However, AGE-PRO is the first study to trace gas evolution and offer measurements of gas disk masses and sizes throughout their lifetimes.
Impact on planets
How protoplanetary disks evolve
Protoplanetary disks evolve over millions of years, with their gas and dust components changing and disappearing. This process determines how long it takes for giant planets to form.
The initial mass, size, and angular momentum of a disk greatly influence the type of planet it can produce—be it gas giants or icy giants—and their migration paths.
Study findings
Gas and dust are consumed at different rates
One of the most surprising discoveries from the survey was that as disks age, their gas and dust are consumed at different rates.
The team found a change in the gas-to-dust mass ratio as the disks evolve.
Unlike dust, which tends to stay longer in the disk, gas disperses relatively quickly before slowing down as the disk ages.
This implies planet-forming disks lose more of their gas when they're young.
Gas retention
More on the findings of the survey
Ke Zhang, the project's principal investigator from the University of Wisconsin-Madison, was surprised that most disks dissipate after a few million years but those that survive have more gas than hoped.
This suggests gaseous planets like Jupiter may have less time to form than rocky ones.
ALMA's sensitivity helped researchers study faint molecular lines in these disks, essentially "fingerprints" identifying different species of gas molecules.
Data collection
Target of the AGE-PRO survey
The AGE-PRO survey targeted 30 protoplanetary disks in three star-forming regions: Ophiuchus, Lupus, and Upper Scorpius. Using ALMA, it took observations of important tracers of gas and dust masses in disks at different evolutionary stages.