Astronomers have taken a major step in understanding how planets form, thanks to the James Webb Space Telescope (JWST). A team led by University of Victoria Ph.D. candidate Dori Blakely used JWST to study a young star called PDS 70, which is located 370 light-years away.
This star has two planets still in the process of forming, giving scientists a rare opportunity to observe how new worlds take shape.
The findings, published in The Astronomical Journal, provide fresh insights into how planets grow by gathering material from the gas and dust surrounding their host stars. The study also suggests that these planets might have disks of material around them, possibly forming future moons.
A Young Star with Planets Under Construction
PDS 70 is a very young star—only about 5 million years old, compared to our Sun, which is 4.6 billion years old. Surrounding the star is a massive disk of gas and dust, similar to what existed around our own Sun before the planets formed. However, in the case of PDS 70, there is a large gap in the disk, where two planets—PDS 70 b and PDS 70 c—are still forming.
This gap acts as a “planetary nursery,” where young planets pull in gas and dust to grow bigger. The researchers were able to observe the planets actively competing with their star for this material. According to Blakely, this study provides a rare look at planets in the middle of their formation process, rather than just studying fully formed planets.
Innovative Techniques with JWST
To capture such detailed images of the system, the team used a special technique with JWST’s Near-Infrared Imager and Slitless Spectrograph (NIRISS). They used a method called Aperture Masking Interferometry (AMI), where a small mask with tiny holes was placed over the telescope’s mirror.
This allowed only a small portion of the light to pass through, creating patterns that revealed hidden details about the planets and their surroundings.
Professor René Doyon, who helped develop JWST’s NIRISS instrument, compared this technique to dimming a bright spotlight to see what lies around it. The method helped detect features that ordinary telescopes would have missed, proving that JWST can uncover planetary details in new ways.
Planets Growing by Gathering Material
The JWST observations confirmed that PDS 70 b and PDS 70 c are still pulling in gas and dust. The researchers used infrared measurements to determine that both planets are actively accumulating material, which is crucial for their development.
This supports the widely accepted idea that planets grow through a process called “accretion,” where they gradually gain mass by pulling in surrounding gas and dust.
By studying these young planets, astronomers can learn more about how giant planets like Jupiter and Saturn formed in our own solar system billions of years ago. Doug Johnstone, a researcher at the National Research Council of Canada, described these observations as a “front-row seat” to planet formation in real time.
Signs of Moon Formation?
The study also found hints that these planets may have rings of material around them, known as circumplanetary disks. These disks could be where moons are forming—just like the ones orbiting Jupiter and Saturn today.
Previous studies of PDS 70 b and c used shorter wavelengths of light and were mostly based on models for small stars or brown dwarfs. However, the new JWST observations used longer wavelengths and revealed extra infrared light, which may indicate the presence of warm material surrounding the planets.
If confirmed, these circumplanetary disks could be key to understanding how moons form around giant planets. This discovery could help explain why gas giants like Jupiter have so many moons.
What’s Next?
One of the most intriguing discoveries was a faint, mysterious light source within the gap of the protoplanetary disk. Scientists are not yet sure what it is—it could be a spiral arm of gas and dust, or possibly a third planet forming in the system.
Follow-up observations with JWST’s other instruments will help determine whether this glow is a new planet, a structure in the disk, or something unexpected.
Analysis and Implications
This study represents a breakthrough in planetary science. By capturing planets still in their infancy, astronomers can test theories about how planets form and evolve. It also highlights how JWST is revolutionizing our understanding of planetary systems beyond our own.
One of the most important findings is the confirmation that young planets compete with their stars for material. This supports the idea that planets do not passively form but must struggle to grow in their early years.
The potential discovery of circumplanetary disks adds another layer of excitement. If confirmed, it would provide direct evidence that moons can form while their host planets are still growing.
Finally, the detection of a possible third planet raises new questions. If there is another planet forming in the PDS 70 system, it could provide further insights into how multiple planets interact during their formation.
Overall, this study is a major step forward in understanding how planetary systems, including our own, come to be. With JWST continuing to make groundbreaking discoveries, astronomers are closer than ever to unlocking the secrets of planet formation.
The research findings can be found in The Astronomical Journal.
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