Astronomers have become very good at finding signs of planet formation around stars. However, to fully understand planet formation, it is important to examine cases where this process has not yet begun.
Looking for something and not finding it can sometimes be even more difficult than finding it, but new detailed observations of the young star DG Taurus reveal that the planet is a smooth protoplanet with no signs of planet formation. It was shown that it has a system disk. This lack of detected planet formation may indicate that DG Taurus is on the eve of planet formation.
Protoplanetary disk and planet growth
Planets form around protostars, which are young stars that are still forming, in disks of gas and dust known as protoplanetary disks. Planets grow so slowly that it is impossible to observe their evolution in situ. Therefore, astronomers observe many protostars at slightly different stages of planet formation to build theoretical understanding.
This time, an international research team led by Satoshi Ohashi of the National Astronomical Observatory of Japan (NAOJ) has developed the Atacama Large Millimeter/Submillimeter Array (alma telescope) will conduct high-resolution observations of the protoplanetary disk surrounding the relatively young protostar DG Taurus, located 410 light-years away in the direction of Taurus. The researchers found that DG Taurus has a smooth protoplanetary disk and no rings that would indicate planet formation. This led the research team to believe that the DG Taurus system could begin forming planets in the future.
Unexpected discoveries and future research
The researchers found that during this pre-planetary stage, dust particles are within 40 astronomical units (about twice the size of Earth’s orbit). Uranus The radius of the central protostar is still small, but beyond this radius the dust particles begin to grow, which is the first step in planet formation. This goes against the theoretical expectation that planet formation begins inside the disk.
These results provide surprising new information about dust distribution and other conditions at the beginning of planet formation. Studying more examples in the future will further deepen our understanding of planet formation.
Reference: “Dust concentration and particle growth in the smooth disk of a DG tau protostar revealed by ALMA triple-band frequency observations” Satoshi Ohashi, Munetake Momose, Akiraka Kataoka, Aya Higuchi E, Takashi Tsukagoshi, Takahiro Ueda, Claudio Codella, Linda Podio, Tomoyuki Hanawa, Nami Sakai, Hiroshi Kobayashi, Satoshi Okuzumi, Hidekazu Tanaka, August 28, 2023, of astrophysical journal.
This research was funded by the Japan Society for the Promotion of Science, the German Foundation, and the European Union.