black hole tagged posts

This artist’s conception portrays a collection of planet-mass objects that have been flung out of the galactic center at speeds of 20 million miles per hour (10,000 km/s). These cosmic “spitballs” formed from fragments of a star that was shredded by the galaxy’s supermassive black hole. Credit: Mark A. Garlick / CfA

Every few thousand years, an unlucky star wanders too close to the black hole at the center of the Milky Way. The black hole’s powerful gravity rips the star apart, sending a long streamer of gas whipping outward. New research shows that not only can the gas gather itself into planet-size objects, but those objects then are flung throughout the galaxy in a game of cosmic “spitball.”

“A single shredded star can form hundreds of these planet-mass objects...

This is a black hole visualization. Credit: Moscow Institute of Physics and Technology

Scientists have devised a method of distinguishing black holes from compact massive objects that are externally indistinguishable from one another. The method involves studying the energy spectrum of particles moving in the vicinity – in one case it will be continuous and in the other it will be discrete.

Black holes, which were predicted by Einstein’s theory of general relativity, have an event horizon – a boundary beyond which nothing, even light, can return to the outside world. The radius of this boundary is called the Schwarzschild radius, ie radius of an object for which the escape velocity is greater than the speed of light, which means that nothing is able to overcome its gravity.

Black holes of ...

In this artist’s rendering, a thick accretion disk has formed around a supermassive black hole following the tidal disruption of a star that wandered too close. Stellar debris has fallen toward the black hole and collected into a thick chaotic disk of hot gas. Flashes of X-ray light near the center of the disk result in light echoes that allow astronomers to map the structure of the funnel-like flow, revealing for the first time strong gravity effects around a normally quiescent black hole. Credit: NASA/Swift/Aurore Simonnet, Sonoma State University

Some 3.9 billion years ago in the heart of a distant galaxy, the intense tidal pull of a monster black hole shredded a star that passed too close...

In principle, nothing that enters a black hole can leave the black hole. This has considerably complicated the study of these mysterious bodies on which generations of physicists have debated ever since 1916, the year their existence was hypothesized as a direct consequence of Einstein’s Theory of Relativity. There is, however, some consensus in the scientific community on the fact that black holes possess an entropy, because their existence would otherwise violate the second law of thermodynamics. In particular, Jacob Bekenstein and Stephen Hawking have suggested that the entropy – a measure of the inner disorder of a physical system – of a black hole is proportional to its area and not to its volume, as would be more intuitive...