I figured with all the nerds and geeks and general knowledge hounds on here this thread would make sense. I am watching/listening to The Universe while cleaning and the show about the most dangerous things in the Universe are pretty cool.
Black Hole -
I think everyone is familiar with a Black Hole in general and the Event Horizon. I had never heard of a Magnetar until I had watched that show. Just alittle info from the Wiki Article.
Magnetars are primarily characterized by their extremely powerful magnetic field, which can often reach the order of ten gigatesla. These magnetic fields are hundreds of thousands of times stronger than any man-made magnet, and quadrillions of times more powerful than the field surrounding Earth. As of 2010, they are the most magnetic objects ever detected in the universe.
When, in a supernova, a star collapses to a neutron star, its magnetic field increases dramatically in strength. Halving a linear dimension increases the magnetic field fourfold.
This thread is for discussion of any known space and or universe discussion. I am doing this as much for me as anything else for information gathering. BTW you can watch many episodes of The Universe on Hulu for free.
Supemassive black hole -
A supermassive black hole is the largest type of black hole in a galaxy, on the order of hundreds of thousands to billions of solar masses. Most, if not all galaxies, including the Milky Way, are believed to contain supermassive black holes at their centers.
Supermassive black holes have properties which distinguish them from lower-mass classifications:
* The average density of a supermassive black hole (measured as the mass of the black hole divided by its Schwarzschild volume) can be very low, and may actually be lower than the density of air. This is because the Schwarzschild radius is directly proportional to mass, while density is inversely proportional to the volume. Since the volume of a spherical object (such as the event horizon of a non-rotating black hole) is directly proportional to the cube of the radius, and mass merely increases linearly, the volume increases by a much greater factor than the mass as a black hole grows. Thus, average density decreases for increasingly larger radii of black holes (due to volume increasing much faster than mass). * The tidal forces in the vicinity of the event horizon are significantly weaker. Since the central singularity is so far away from the horizon, a hypothetical astronaut travelling towards the black hole center would not experience significant tidal force until very deep into the black hole.
here are several models for the formation of black holes of this size. The most obvious is by slow accretion of matter starting from a black hole of stellar size. Another model of supermassive black hole formation involves a large gas cloud collapsing into a relativistic star of perhaps a hundred thousand solar masses or larger. The star would then become unstable to radial perturbations due to electron-positron pair production in its core, and may collapse directly into a black hole without a supernova explosion, which would eject most of its mass and prevent it from leaving a supermassive black hole as a remnant. Yet another model involves a dense stellar cluster undergoing core-collapse as the negative heat capacity of the system drives the velocity dispersion in the core to relativistic speeds. Finally, primordial black holes may have been produced directly from external pressure in the first instants after the Big Bang.