Max Planck Institute for Astronomy | 2019 Sep 12
The role of magnetic fields in the formation of stars has been a hot topic among astrophysicists for decades. Now Juan Diego Soler of the Max Planck Institute for Astronomy in Heidelberg, Germany, has shown that magnetic fields can favour and advance the compression of interstellar matter – a prerequisite for the formation of stars. This conclusion is based on the finding that in star forming regions the interstellar matter, depending on its density, is sometimes oriented parallel to, sometimes rather perpendicular to, the magnetic field lines.
- Infrared light and magnetic field lines toward the Orion A cloud, revealed by the Herschel and Planck space observatories. With enough gas to form tens of thousands of stars like the Sun, this is the most nearby site of high-mass star formation. The colours indicate the light emitted by interstellar dust grains. The grey bands show the orientation of the magnetic field. Credit: JD Soler/MPIA
Stars form from compressed clouds of the interstellar medium. It consists of gas (mostly hydrogen) and tiny particles of carbon and silicates, which the astrophysicist calls dust. If the interstellar medium reaches a sufficiently high density, the self-gravity leads to a collapse of the initially cold matter down to hot stars. How such clouds form and condense, however, is not yet fully understood. Magnetic fields are a major component of the interstellar medium in the Milky Way and other galaxies. They contribute significantly to the total pressure, which balances it against gravity. Still, their exact role in the process of star formation is the subject of lively discussions.
In order to approach this puzzle, Juan Diego Soler of the Max Planck Institute for Astronomy in Heidelberg investigated the orientation of magnetic fields with respect to the density distribution towards the most nearby regions of star formation at distances of up to 450 parsecs (1450 lightyears) from the Sun. "The idea is that if the magnetic field has a strong influence on the interstellar medium, it should shape its density structures," Soler explained.
In fact, in all cases he found a parallel alignment of the magnetic fields to the diffuse, i.e. less dense, component of the interstellar medium. However, at higher densities there was a gradual shift in alignment towards larger angles. In the densest zones, the magnetic field was even perpendicular to the structures of the interstellar medium. ...
Using Herschel and Planck Observations to Delineate the Role
of Magnetic Fields in Molecular Cloud Structure ~ Juan D. Soler