ALMA observes dusty sites of planet formation

The Atacama Large Millimeter/Submillimeter Array (ALMA) successfully observed planet formation sites by detecting high concentrations of dust particles, the material that forms planets, outside the orbits of newly formed planets.

An international research team led by Kiyoaki Doi, who was in his doctoral course at the time. student at the National Astronomical Observatory of Japan (NAOJ)/The Graduate University for Advanced Studies and currently a postdoctoral researcher at the Max Planck Institute for Astronomy, he conducted high-resolution observations of a protoplanetary disk around a young star called PDS 70. I did. Wavelength 3mm with ALMA telescope.

The object has two known planets, and new ALMA observations reveal a local accumulation of dust particles outside the planet’s orbit. This finding suggests that planets that have already formed accumulate planetary material, facilitating the potential formation of the next planet. This research will contribute to elucidating the formation process of planetary systems consisting of multiple planets like the solar system.

The paper, titled “Asymmetric dust accumulation in the PDS 70 disk revealed by ALMA band 3 observations,” has been accepted for publication in Astrophysical Journal Letters. Available on the arXiv preprint server.

To date, more than 5,000 planets have been identified inside and outside our solar system. In some cases, planets can form planetary systems consisting of multiple planets. These planets are thought to arise from micron-sized dust particles in protoplanetary disks surrounding young stars. However, it is still unclear how these dust particles accumulate locally and lead to the formation of planetary systems.

PDS 70 is the only known object with a planet already formed within its protoplanetary disk, confirmed by optical and infrared observations. Determining the distribution of dust particles in this object provides insight into how already formed planets interact with the surrounding protoplanetary disk, potentially influencing subsequent planet formation. You will get it.

Previous ALMA observations at 0.87 mm revealed a ring-shaped emission from dust particles outside the planet’s orbit. However, the emission source may be optically thick (opaque, with dust particles in the foreground obscuring those behind), and the observed emission distribution may not accurately reflect the distribution of dust particles. There is a gender.

A research team led by Kiyoaki Doi used ALMA to conduct high-resolution observations of the protoplanetary disk near PDS 70 at a wavelength of 3 mm. Observation at 3 mm is optically thinner (more transparent) and provides a more reliable distribution of dust particles.

The new observations at 3 mm show a different distribution from previous observations at 0.87 mm, revealing that dust emissions are concentrated in specific directions within the planet’s outer dust ring. . This suggests that the dust particles that planets are made of accumulate in small areas, forming localized clumps.

The dust clumps on the planet’s exterior suggest that the planet that has already formed is interacting with the surrounding disk, concentrating dust particles in a narrow area at the outer edge of its orbit. These hardened dust particles are thought to grow into new planets.

The formation of planetary systems like the solar system can be explained by the fact that planets are formed sequentially from the inside to the outside by repeating this process. This research contributed to the understanding of planetary system formation by observing how already formed planets interact with their surroundings and causing the formation of subsequent planets.

Kiyoaki Doi, who led this research, said, “A celestial object is made up of multiple components, each of which emits radiation at different wavelengths.Therefore, by observing the same celestial object at multiple wavelengths, we can “It gives you a unique perspective.”

“With PDS 70, planets were discovered at optical and infrared wavelengths, but protoplanetary disks were observed at millimeter wavelengths. This study shows that even within ALMA’s observation wavelength range, the disk shows that they exhibit different forms.”

“This highlights the importance of observations across different wavelengths, including multiwavelength observations with ALMA. A comprehensive understanding of the entire system requires using different telescopes and observing targets in different observation settings. It is necessary to observe multiple components.