The Very Large Array may tell researchers about the earliest stages of planet formation. Scientists have now seen unprecedented details of the inner portion of a dusty disk surrounding a star.
The star that the researchers took a closer look at is located about 450 light-years from Earth. It was first studied in 2014 with the Atacama Large Millimeter/submillimeter Array (ALMA). This particular array produced the best image ever of planet formation in process.
When a star is born, it accretes a dusty disk of material around it. This dust then forms rocky or gaseous "balls" due to the force of gravity. These chunks of material then go on to form planets over time.
ALMA showed details of the system in the outer portion of the disk. However, it was difficult to see the inner layers due to the thickness of the dust near the star. That's why researchers turned to the VLA, which received longer wavelengths.
Using the VLA, researchers saw a distinct clump of dust in the inner region of the disk that was roughly 3 to 8 times the mass of Earth. This clump could, in theory, be the beginning stages of planet formation in this system.
"This is an important discovery, because we have not yet been able to observe most stages in the process of planet formation," said Carlos Carrasco-Gonzalez from the Institute of Radio Astronomy and Astrophysics (IRyA). "This is quite different from the case of star formation, where, in different objects, we have seen stars in different stages of their life cycle. With planets, we haven't been so fortunate, so getting a look at this very early stage in planet formation is extremely valuable."
The researchers also conducted further analysis of the VLA data. This revealed that the inner region of the disk contains grains that are as large as one centimeter in diameter. This region is the most likely to host Earth-like planets. As these grains grow, they collect more and more grains and could, over time, form planets.
"These VLA observations are the most sensitive and show the most detail of any yet made of HL Tau's disk at these longer wavelengths," Claire Chandler of the National Radio Astronomy Observatory said. "The VLA's ability to produce such high-quality images in this region is very important to advancing our understanding of these initial stages of planet formation."
The findings are published in the Astrophysical Journal.
