NASA’s Hubble Space Telescope Yields Clear View of Optical Jet in Galaxy M87
A NASA Hubble Space Telescope (HST) view of a 4,000 light-year long jet of plasma emanating from the bright nucleus of the giant elliptical galaxy M87. This ultraviolet light image was made with the European Space Agency’s Faint Object Camera (FOC), one of two imaging systems aboard HST. This photo is being presented on Thursday, January 16th at the 179th meeting of the American Astronomical Society meeting in Atlanta, Georgia. M87 is a giant elliptical galaxy with an estimated mass of 300 billion suns. Located 52 million light-years away at the heart of the neighboring Virgo cluster of galaxies, M87 is the nearest example of an active galactic nucleus with a bright optical jet. The jet appears as a string of knots within a widening cone extending out from the core of M87. The FOC image reveals unprecedented detail in these knots, resolving some features as small as ten light-years across. According to one theory, the jet is most likely powered by a 3 billion solar mass black hole at the nucleus of M87. Magnetic fields generated within a spinning accretion disk surrounding the black hole, spiral around the edge of the jet. The fields confine the jet to a long narrow tube of hot plasma and charged particles. High speed electrons and protons which are accelerated near the black hole race along the tube at nearly the speed of light. When electrons are caught up in the magnetic field they radiate in a process called synchrotron radiation. The Faint Object Camera image clearly resolves these localized electron acceleration, which seem to trace out the spiral pattern of the otherwise invisible magnetic field lines. A large bright knot located midway along the jet shows where the blue jet disrupts violently and becomes more chaotic. Farther out from the core the jet bends and dissipates as it rams into a wall of gas, invisible but present throughout the galaxy which the jet has plowed in front of itself. HST is ideally suited for studying extragalactic jets. The Telescope’s UV sensitivity allows it to clearly separate a jet from the stellar background light of its host galaxy. What’s more, the FOC’s high angular resolution is comparable to sub arc second resolution achieved by large radio telescope arrays.
Willem Jacob van Stockum (November 20, 1910-June 10, 1944) was a mathematician who made an important contribution to the early development of general relativity.
Van Stockum was born in Hattem in the Netherlands. His father was a mechanically talented officer in the Dutch Navy. After the family (less the father) relocated to Ireland in the late 1920s, Willem studied mathematics at the Trinity College, Dublin, where he earned a gold medal. He went on to earn an M.A. from the University of Toronto and his Ph.D. from University of Edinburgh.
In the mid nineteen thirties, van Stockum became an early enthusiast of the then new theory of gravitation, general relativity. In 1937, he published a paper which contains one of the first exact solutions in general relativity which modeled the gravitational field produced by a configuration of rotating matter, the van Stockum dust, which remains an important example noted for its unusual simplicity. In this paper, van Stockum was apparently the first to notice the possibility of closed timelike curves, one of the strangest and most disconcerting phenomena in general relativity.
The chronology protection conjecture is a conjecture by the physicist Professor Stephen Hawking that the laws of physics are such as to prevent time travel on all but sub-microscopic scales. Mathematically, the permissibility of time travel is represented by the existence of closed timelike curves.
An Overview and Comparison by Dr. David Lewis Anderson
A Tipler Cylinder uses a massive and long cylinder spinning around its longitudinal axis. The rotation creates a frame-dragging effect and fields of closed time-like curves traversable in a way to achieve subluminal time travel to the past.
We see a pulsar, then, when one of its beams of radiation crosses our line-of-sight. In this way, a pulsar is like a lighthouse. The light from a lighthouse appears to be “pulsing” because it only crosses our line-of-sight once each time it spins. Similarly, a pulsar “pulses” because we see bright flashes every time the star spins.