2024-03-06 04:00:00
The James Webb Space Telescope (JWST) has for the first time captured winds from an old planet-forming disk that is actively dispersing its gas content.
Knowing when the gas disperses is important, since it limits the time left for nascent planets to consume the gas in their environment, according to a team of scientists led by Naman Bajaj, from the University of Arizona, published in the Astronomical Journal. , and Dr. Uma Gorti of the SETI Institute,
At the center of this discovery is the observation of TCha, a young star (relative to the Sun) enveloped by an eroding disk notable for its enormous dust space, approximately 30 astronomical units of radius.
For the first time, astronomers have imaged dispersing gas (also known as winds) using the four lines of the noble gases neon (Ne) and argon (Ar), one of which is the first detection in a forming disk of planets.
The images of [Ne II] show that the wind comes from an extended region of the disk.
“These winds might be driven by high-energy stellar photons (light from the star) or by the magnetic field that weaves the planet-forming disk,” Naman said in a statement.
Planetary systems like our Solar System appear to contain more rocky objects than gas-rich ones.
Around our Sun, they include the inner planets, the asteroid belt, and the Kuiper belt.
But scientists have long known that planet-forming disks start with 100 times more mass in gas than in solids, leading to a pressing question: When and how does most of the gas leave the disk/system?
During the early stages of planetary system formation, the planets coalesce into a rotating disk of tiny gas and dust around the young star.
These particles clump together and form larger and larger pieces called planetesimals. Over time, these planetesimals collide and stick together, eventually forming planets.
The type, size and location of planets that form depend on the amount of material available and how long it remains in the disk.
Thus, the outcome of planet formation depends on the evolution and dispersion of the disk.
The same group, in another paper led by Dr. Andrew Sellek of Leiden Observatory, performed simulations of stellar photon-driven scattering to differentiate between the two.
They compare these simulations with real observations and find that scattering by high-energy stellar photons can explain the observations and therefore cannot be excluded as a possibility.
Sellek described how “JWST’s simultaneous measurement of all four lines was crucial in pinning down the properties of the wind and helped us demonstrate that significant amounts of gas are being dispersed.”
To put it in context, researchers calculate that the mass dispersed each year is equivalent to that of the Moon.
A companion paper, currently under review in the Astronomical Journal, will detail these results.
The line [Ne II] It was first discovered several planet-forming disks away in 2007 with the Spitzer Space Telescope and was soon identified as a wind tracer by project leader Prof. Pascucci of the University of Arizona; This transformed research efforts focused on understanding gas dispersion in disks.
The discovery of [Ne II] spatially resolved and the first detection of [Ar III] using the JWST might become the next step towards transforming our understanding of this process.
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