Study reveals initial conditions for planet formation

Using the Atacama Large Millimeter/submillimeter Array (ALMA) telescope, researchers have shed light on the beginnings of planet formation. The team observed a protostar named DG Taurus ( or DG Tau), which displayed a smooth and unblemished protoplanetary disk, revealing the initial conditions when planets begin to form.

In the above picture, the smooth appearance, absent of ring-like structures, indicates a phase shortly preceding planet formation.

Planets are believed to form from the interstellar dust and gas in a protostar's surrounding disk. While many disks display ring-like structures hinting at the presence of a plane, finding a pristine disk without such signatures has been elusive.

The team, led by Project Assistant Professor Satoshi Ohashi from the National Astronomical Observatory of Japan (NAOJ), discerned a uniformly smooth disk without the characteristic ring patterns often found in older protostars. The findings suggest that DG Tau might be on the brink of planet formation. 

Understanding the dynamics of such young protoplanetary disks is crucial for unravelling the mysteries of how life began on Earth.

Further, the researchers observed the disk across different wavelengths, obtaining insights into dust size and distribution, suggesting the disk's outer regions as the potential starting point for planet formation. The finding challenges previously held beliefs that the inner disk was the primary inception point.

The team also observed a high dust-to-gas ratio in the midplane of the protoplanetary disk around DG Tau - hinting that the disk may be well-prepared for planet formation soon.

"ALMA has so far succeeded in capturing a wide variety of disk structures and has revealed the existence of planets. On the other hand, to answer the question, 'How does planet formation begin?', it is important to observe a smooth disk with no signature of planet formation. We believe that this study is very important because it reveals the initial conditions for planet formation," said Professor Satoshi Ohashi.

Their findings are published in the Astrophysical Journal.