Scientists at the Harvard-Smithsonian Center for Astrophysics measured for the first time the thickness of a disk of gas and dust in three protoplanetary systems.
Astronomers at the Harvard-Smithsonian Center for Astrophysics Richard Teague and David Wilner, along with a team, have completed the first direct comparison of the thickness of a disk of gas and dust. This is necessary in order to understand from what and how different planets are formed.
The authors made a model based on data from ALMA, Hubble and Gemini on the three planetary disks. They chose the ones that would work best for their job: the systems are not too tilted, they have enough carbon monoxide and dust to measure these components, and the discs display multiple rings. The rings scatter light and are needed to estimate the thickness of the protoplanetary disk.
Astronomers have found that in the two systems, gas and dust, which are at a distance of about 100 astronomical units (one astronomical unit is approximately equal to the distance from the Earth to the Sun), have the same structure, but at a greater distance, dust particles have a lower vertical height than CO gas. … In the third system, the two components have the same shape at all distances.
Scientists argue that a gas to dust mass ratio in excess of 100 (typical value for the interstellar medium) can be explained by the example of the first two systems studied. The team also concludes that the thickness of the dusty and gaseous disk is not just a function of mass, age, or spectral type of the star, but their relationship is not yet understood.
The authors are afraid to draw global conclusions, since they studied only three systems, therefore, the mechanisms of ring formation are not fully determined. The studied systems were large on average; perhaps, for other sizes, the data obtained will not work.
The effects of turbulence and dust settling also remain uncertain. Additional observations and simulations will help characterize the disks of other systems, as well as detail the formation of different planets.