New Spin on Stars
The "Angular Momentum Problem" is yet another puzzle of astrophysics. Since the time of Pierre Laplace, scientists have believed that stars collapse from rotating disks of gas. If the disk angular momentum were conserved, a star would spin itself apart before igniting. Where does the angular momentum go? One big clue is the powerful jets seen erupting from infant stars. The jets follow magnetic field lines, as if angular momentum were powering huge electric dynamoes.
In the November 1 issue of NATURE, astronomers from the Anglo-Australian Observatory put forth a model where the jets carry away angular momentum. Infrared observations of protostar HH135-36 in the Carina Nebula show jets extending billions of kilometres. The photo of HH 135-36 is a bit fuzzy because infrared wavelengths are long. This model is also recounted in Space.com. The exact mechanism turning angular momentum to magnetism is still considered a mystery.
Twin jets following magnetic field lines are signs of a Black Hole. Today's Washington Post recounts how astronomers realised that Black Holes are at the centre of galaxies. This conclusion took decades of work. "Something very profound is going on here, and the formation of Black Holes and galaxies is related in some way," states astrophysicist Juna Kollmeier. It may take more decades to figure out that a Black Hole is in the second last place humans would expect. It may be rising in front of our faces every morning.
Like an electron, a Black Hole can be described by just three numbers: Mass, spin and electric charge. In an electron, these numbers are quantized into discrete values. As if they were produced on an assembly line, every electron has the same charge and mass! Researchers like Carl Brannen are hot on the trail of particle masses. Black Holes, on the other hand, can have almost any mass.
Lower than a certain mass Black Holes are prone to evaporate in Hawking radiation. There is almost no upper limit to Black Hole size; they could be huge enough to clear A Hole in the Universe. For that reason Black Holes are likely to form a majority of the "dark" mass. They could be ubiquitous, seeding formation of galaxies, stars and even smaller objects. The protons, neutrons and electrons that form life compose only 4.507034% of the Universe. It is amazing that we add up to that much.
More Space news is in the new Carnival of Space!