![]() ![]() Individual mouthpiece choices and embouchures resulting in various sounding lengths will result in different degrees of that octave stretching so one person ends up not experiencing the issue and the next one has to resort to all kinds of alternate fingerings. This is well known on Selmer Mark 6s, and since most modern saxophones are copies of that design it carries over to a lot of them. Any number of older saxophones also have "C# helper" levers that partially close the C# tone hole cup when the octave key's depressed.įor the Selmer Mark 6 (and it might have been introduced before that) the decision was made to lower the pitch of the upper C#, which resulted in the lower C# being flat. Older horns, the design choice was to make the lower C# in tune and the upper one would be sharp - it's a lot easier to lip notes down than up. It would open up many new possibilities and perhaps solve a long-standing problem of what triggers supernovae explosions.Click to expand.Well, the real thing is that on saxophone the C# octave is too big (the upper one's more than exactly 2X the frequency of the lower one). "Nevertheless, this is provocative and interesting. "This is such a break from 40 years of traditional thinking that one should be cautious trumpeting it," he said. "The sound waves reinforce the shock wave (created by the collapsed star) until it finally explodes aspherically."īurrows said that others who study supernova explosions in computer experiments will be skeptical of his team's results - and should be. "Sound also generates pressure, which pushes the exciting streams of infalling matter to the opposite side of the core, further driving the core oscillations in a runaway process," Burrows said. Typical sound frequencies are about 200 to 400 hertz, in the audible range bracketing middle C. Within hundreds of milliseconds, the inner core vibrations become so intense that they actually generate sound waves. ![]() Burrows has posted the movies on his Website at zenith.as./~burrows/brileyĬollapsing material falls lopsidedly onto the inner core and soon excites oscillations at specific frequencies in the simulations. The team got a clear picture of what likely happens by making movies from their simulations. Their research is funded by the National Science Foundation, the Department of Energy, and the Joint Institute for Nuclear Astrophysics. They are publishing the research in the Astrophysical Journal. The team has used their models to make billions of calculations on computer clusters in the UA astronomy department, at Berkeley's supercomputer center and elsewhere, checking their analysis for the past year. He added, "We were quite sure when we started seeing this phenomenon that we were seeing sound waves, but it was so unexpected that we kept rechecking and retesting our results." In these computer runs, it's these sound waves that actually cause the star to explode, not the neutrinos." And after 600, 700 or 800 milliseconds, this oscillation becomes so vigorous that it sends out sound waves. They show that after about 500 milliseconds, the inner core begins to vibrate wildly. "And they allow us to follow the development to explosion for a longer time than other models do. "Our simulations show that the inner core starts to execute pulsations," Burrows said. Burrows team's simulations also characterize the natural motion of a supernova core, something that other detailed models do not. His team's detailed models involve a million steps, or about five times as many as typical models that calculate only the first few hundred milliseconds of supernovae events. So theorists have focused their work on what might revive the shock wave into becoming a supernova explosion.Īccording to Burrow's new results, part of the problem is that other computer models don't run long enough. However, in all the best recent simulations, the shock wave stalls. When the white dwarf reaches a critical mass (about 1.5 times the mass of the sun), it collapses and creates a spherical shock wave, all within less than half a second before the star would explode as a supernova. (Graphic: Courtesy of Adam Burrows, UA)Ī supernova is a massive star that has burned for 10 million to 20 million years and developed a hot, dense 'white dwarf' star about the size of Earth at its core. The colors reflect the entropies on the shells, where entropy is a measure of heat content. The scale is ~2000 kilometers on a side and the time is ~800 milliseconds after the bounce at nuclear densities of the collapsed core. The remnant neutron star is the green "dot" in the center and the outer shells are just interior to the blast wave that has been launched. Computer-generated image of the "isodensity contours" for the core of an 11-solar-mass star explosion. ![]()
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