Just how stars and black holes in the Universe are able to form from rotating matter is one of the big questions of astrophysics. What we do know is that magnetic fields figure prominently into the picture. However, our current understanding is that they only work if matter is electrically well conductive—but in rotating discs this isn’t always the case. Now, a new publication by Helmholtz-Zentrum Dresden-Rossendorf physicists in the scientific journal Physical Review Letters shows how magnetic fields can also cause turbulences within “dead zones,” thus making an important contribution to our current understanding of just how compact objects form in the cosmos.
When Johannes Kepler first proposed his laws of planetary motion in the early days of the 17th century, he could not have foreseen the central role cosmic magnetic fields would play in planetary system formation. Today, we know that in the absence of magnetic fields, mass would not be able to concentrate in compact bodies like stars and black holes. One prominent example is our solar system, which formed 4.6 billion years ago through the collapse of a gigantic cloud of gas, whose gravitational pull concentrated particles in its center, culminating in the formation of a large disc. “These accretion discs are extremely stable from a hydrodynamic perspective as according to Kepler’s laws of planetary motion angular momentum increases from the center towards the periphery,” explains HZDR’s own Dr. Frank Stefani. “In order to explain the growth rates of stars and black holes, there has to exist a mechanism, which acts to destabilize the rotating disc and which at the same time ensures mass is transported towards the center and angular momentum towards the periphery.”
Read more at: Phys.org