Stellar News

While concerned with massive objects such as neutron stars and black holes in her work, Martyna Chruslinska loves the lightweight feeling of figure skating in her spare time. more

In dense stellar environments, stars can collide. If there is a massive black hole nearby – at the centre of galaxies – these collisions can be so energetic that the two stars are completely destroyed upon collision, leaving behind an expanding gas cloud. While the collision itself can generate a very luminous flare for several days, there might be an even brighter flare that can last up to many months, as the gas cloud is captured by the nearby black hole. A research team led by MPA has estimated the observables of such powerful events for the first time using the two state-of-the-art codes AREPO and MESA, developed at MPA. more

Throwing one star into another into another star does not bode well for either star. However, given the right conditions and the right types of stars this can lead to the stars merging and forming one single object. If one of the stars is a neutron star (the dense stellar remnant after a supernovae) it can sink to the center of the other star replacing that star’s core. Such objects are called Thorne-Żytkow objects (TŻOs) as they where first proposed by Kip Thorne and Anne Żytkow. Now an international team of astrophysicists led by the Max Planck Institute for Astrophysics (MPA) has re-evaluated what these TŻOs look like and whether we can find them. more

Neutrinos are the driving factor for core-collapse supernovae, the violent death of massive stars. According to the neutrino-driven mechanism they are responsible for transferring energy from the hot proto-neutron star (PNS) to the surrounding material. So far, numerical simulations assumed that neutrinos retain their flavor during propagation. Max Planck researchers have now shown that allowing for flavor conversions has a direct influence on the supernova dynamics. more

Originally a chemist, Taeho Ryu started studying physics, because he was bored during an extended hospital stay. more

Black holes, resulting from the death of massive stars, are some of the most exotic and powerful objects in the Universe. Since even light cannot escape these objects, the quasi-periodic signals coming from the gas falling into the black hole serve as a probe to infer a great deal of information about the black hole and its surrounding environment. The most-commonly observed quasi-periodic signal is thought to originate from the wobbling of hot gas around the black hole, like a spinning top. One problem, though, is that inferred size of this (isolated) corona seemed to be inconsistent with estimations from other observables. With our recent, state-of-the-art computer simulations, involving a more realistic geometry of the accretion flow, we demonstrated for the first time, that the presence of a disc around the corona significantly slows down its precession, relieving much of the tension between this model and observations. These results thus have important implications for studies of black hole properties and how black hole systems form and evolve. more

Massive stars often reside in multiple star systems, therefore it is expected that mergers of their final stages, neutron stars or black holes, contribute significantly to gravitational wave sources. A team at MPA has now studied the evolution of millions of quadruple star systems and estimated that a significant fraction of the black hole – black hole mergers detected by LIGO come from such multiple star systems rather than simple binaries. more