This paper explores the origins of our Solar System and extrasolar system that are one of the most important themes in modern astronomy. Planets are considered to be formed in disks around young stellar objects in the course of star formation. An international team led by Nagayoshi Ohashi focused on disks around 19 protostellar systems that are only 10,000 to 100,000 years old, and observed the radio emission emitted from dust grains with Atacama Millimeter/submillimeter Array (ALMA). The observations were made at a very high angular resolution of ALMA, 0.04 arcseconds corresponding to the size of a coin seen at a distance of 100 km, to examine the structure of the protostellar disks in detail. This is the first systematic study to investigate the detailed structure of disks around a large sample of protostars with such a high angular resolution. Their research revealed that disks around protostars are significantly different from those around more evolved young stars. The difference suggests that actual formation of planetary systems progresses rapidly in the 100,000 years to 1,000,000 years after star formation begins. This survey called “Early Planet Formation in Embedded Disks (eDisk)” was led by Ohashi as a Large Program of ALMA, and a series of eDisk papers (so far 14) have been published. These papers were mostly led by graduate students or young postdocs, demonstrating that the eDisk program also plays an important role in educating the next generation scientists.

Related links：

• ALMA Digs Deeper into the Mystery of Planet Formation

• Early Planet Formation in Embedded Disks (eDisk). I. Overview of the Program and First Results

• This research was presented in a paper “Early Planet Formation in Embedded Disks (eDisk). I. Overview of the Program and First Results” by Ohashi et al. appeared in The Astrophysical Journal.