PDS 70 is unique because it is the only known star with confirmed planets still embedded in its protoplanetary disk.
Scientists using the Atacama Large Millimeter/submillimeter Array (ALMA) have observed a significant concentration of dust grains—materials critical for planet formation—outside the orbits of two known planets around the young star PDS 70. As explained by researchers, these findings provide valuable data on how planetary systems like our solar system may form.
An international team led by Kiyoaki Doi, now a postdoctoral researcher at the Max Planck Institute for Astronomy, conducted this study. The team observed PDS 70 at a wavelength of 3 mm using ALMA, which allowed them to identify the dust distribution in the star’s protoplanetary disk with greater accuracy than previous observations at shorter wavelengths.
Dust Accumulation and Planet Formation
PDS 70 is unique because it is the only known star with confirmed planets still embedded in its protoplanetary disk. Previous studies identified ring-shaped dust emissions at shorter wavelengths, but these observations were limited by the opacity of the disk, which made it challenging to determine the precise location of the dust grains.
Using ALMA’s longer wavelength observations, researchers discovered a concentrated clump of dust grains in the outer ring of the disk. This finding suggests that the existing planets influence the disk, concentrating material in specific regions. These regions could eventually lead to the formation of additional planets.
The Process of Sequential Planet Formation
The study supports the idea that planets form sequentially, beginning closer to the star and gradually moving outward. As planets form, their gravitational influence gathers dust at the outer edges of their orbits, setting the stage for new planets to develop. This process could explain how multi-planetary systems are formed over time.
According to Doi, observing celestial objects at multiple wavelengths is essential for understanding their various components. PDS 70 demonstrates this clearly, with planets visible at optical and infrared wavelengths and the surrounding disk observed in millimeter wavelengths. These findings highlight the importance of combining data from different telescopes to build a complete picture of planetary system formation.