Max Planck Institute for Extraterrestrial Physics | 2019 Sep 06
How do stars and planets form? Scientists are now one step closer to pinning down the conditions for the formation of proto-stellar disks. Observations of three systems in the early stages of star formation in the Perseus cloud revealed that the profile of the angular momentum in these systems is between that expected for a solid body and pure turbulence, indicating that the influence of the core extends further out than previously thought. These findings could lead to more realistic initial conditions for numerical simulations of disk formation.
The main steps of star and planet formation are well understood: a dense, interstellar cloud will collapse under its own gravity; a central core forms as well as a proto-stellar disk due to the conservation of angular momentum; finally, after about 100,000 years or so, the star will become dense enough to ignite nuclear fusion at its centre and so will start to shine, while in the disk, planets will form. But there are still many open questions about the details of this process, e.g. what is the role of angular momentum in disk formation or how does the circum-stellar disk gather most of its mass?
An international team of scientists led by the Max Planck Institute for Extraterrestrial Physics (MPE) has now observed three of the youngest proto-stellar sources in the Perseus molecular cloud. These sources are close to edge-on in the plane of the sky, allowing a study of the velocity distribution of the dense cloud.
“This is the first time that we were able to analyze the gas kinematics around three circum-stellar disks in early stages of their formation,” states Jaime Pineda, who led the study at MPE. “All systems can be fit with the same model, which gave us the first hint that the dense clouds do not rotate as solid body.” A solid body rotation is the simplest assumption, which describes the gas in the dense cloud with a fixed angular speed at any given radius. The model best describing all three systems is in between those expected for solid body rotation and pure turbulence. ...
The Specific Angular Momentum Radial Profile in Dense Cores:
Improved Initial Conditions for Disk Formation ~ Jaime E. Pineda et al