What does a builder of worlds need to form planets? A protoplanetary disk made out of a suitable material in which differences in density can develop, and an object at the center of the system that acts as a common center of gravity and uses its force of attraction to prevent the cloud of material from floating off into infinity. Until now it had been assumed that these conditions were met primarily by stars. But apparently much more exotic planetary systems are also conceivable, as Japanese researchers have now described in a study. The scientists took a closer look…

A black hole grows by being fed from a so-called accretion disk that supplies it with fresh matter. This disk is made up of plasma, ionized gas that orbits in continuous spirals around the black hole at high speeds. This plasma is constantly heated by internal collisions. To an observer, however, an accretion disk won’t look like a classic disk (like, for example, Saturn’s rings). This is because a black hole generates such an unbelievably large force of gravity that radiation from the rear part of the disk becomes distorted as it moves toward the observer. Now, researchers at…

Black holes suck in anything that gets too close to them—even light. In their interiors, researchers imagine objects that, according to current physics, should not even exist: singularities, where matter becomes infinitely dense and hot and classical physics breaks down. The area around a black hole is also a hot subject of discussion. In particular, astrophysicists run into problems when they consider a black hole simultaneously with the general theory of relativity and quantum physics. One problem arises with the quantum states of all the particles that fall into the black hole. For the rest of the universe, information…

Dass sich im Zentrum der Milchstraße mit Sagittarius A* ein supermassives Schwarzes Loch befindet, ist seit den 1970er-Jahren bekannt. Die Röntgenquelle hat etwa vier Millionen Sonnenmassen. Die Milchstraße ist damit nicht die Ausnahme, sondern die Regel: Im Herzen jeder normalen Galaxie schlägt ein dunkles Herz. Aber was passiert, wenn sich zwei Galaxien begegnen, wie es in der Geschichte des Universums schon oft passiert ist? Dann geht oft eines der Schwarzen Löcher verloren, oder genauer gesagt: Es geht auf Wanderschaft. Forscher u.a. der Yale University haben anhand einer Simulation jetzt untersucht, wie viele ultraschwere Schwarze Löcher es in einer normal großen…