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Nucleosynthesis, Cosmic Radiation, and the Universe
Published in Ivan G. Draganić, Zorica D. Draganić, Jean-Pierre Adloff, Radiation and Radioactivity on Earth and Beyond, 2020
Ivan G. Draganić, Zorica D. Draganić, Jean-Pierre Adloff
In nature, it is most likely that only supernova explosions can provide the necessary conditions for the r-process. There are two types of supernova explosions. One of these (called type I) represents the final evolutionary stage of an old star of relatively moderate mass, corresponding to 1.2 to 1.5 solar masses. The entire star disintegrates in a giant thermonuclear explosion within a few seconds. The temperatures reached in various layers of the star range from 109 to 1010 degrees kelvin. The second type of supernova explosion (type II) occurs only in stars with masses at least eight to ten times that of the Sun. The core of these stars consists of onion-like layers which represent different stages of the star’s life. A computer model suggests that these layers consume a progressive series of nuclear fuels: in the outer layers hydrogen is converted into helium; in the next, helium into carbon and oxygen; and, closer to the stellar core, carbon and oxygen give rise to neon, magnesium, and silicon.
The Origin of the Elements and Earth
Published in Dexter Perkins, Kevin R. Henke, Adam C. Simon, Lance D. Yarbrough, Earth Materials, 2019
Dexter Perkins, Kevin R. Henke, Adam C. Simon, Lance D. Yarbrough
Where did all the heaviest elements, such as gold or uranium, come from? In large part, they came from supernovas, and supernovas are creating them today. A crucial balance exists in stable stars. Gravity holds the star together and fusion in the center provides outward pressure. As a star runs out of fusible elements, it can collapse and explode. When massive stars end their lives in supernovas, the short-lived (weeks or months) but huge explosions have immense energy. With a few exceptions, fusion in star interiors is incapable of producing elements heavier than iron. However, supernovas have enough energy to create and eject heavier elements into space—elements that may later become parts of new nebula and form new stars and solar systems. These new stars eventually become old and die, and the heavy elements are recycled. During the last 500–1000 years, astronomers have seen several supernovas (some with the naked eye) in our Milky Way and observed many (by telescope) in distant galaxies.
Nuclear and Hydro Power
Published in Anco S. Blazev, Energy Security for The 21st Century, 2021
Supernovae events are extremely luminous and noisy, and cause a burst of radiation that often briefly outshines an entire galaxy, before fading from view over several weeks or months. During this short interval a supernova can radiate as much energy as the Sun is expected to emit over its entire life span.
Light, the universe and everything – 12 Herculean tasks for quantum cowboys and black diamond skiers
Published in Journal of Modern Optics, 2018
Girish Agarwal, Roland E. Allen, Iva Bezděková, Robert W. Boyd, Goong Chen, Ronald Hanson, Dean L. Hawthorne, Philip Hemmer, Moochan B. Kim, Olga Kocharovskaya, David M. Lee, Sebastian K. Lidström, Suzy Lidström, Harald Losert, Helmut Maier, John W. Neuberger, Miles J. Padgett, Mark Raizen, Surjeet Rajendran, Ernst Rasel, Wolfgang P. Schleich, Marlan O. Scully, Gavriil Shchedrin, Gennady Shvets, Alexei V. Sokolov, Anatoly Svidzinsky, Ronald L. Walsworth, Rainer Weiss, Frank Wilczek, Alan E. Willner, Eli Yablonovitch, Nikolay Zheludev
Supernovas are the explosion of stars when they begin to collapse due to the exhaustion of their nuclear fuel. A milkyway galaxy such as ours experiences a supernova about every 30 years. Depending on how non-spherical the explosion and resulting collapse of the star is, a supernova may be a significant source of gravitational waves. Since gravitational waves are so penetrating they would be an excellent way to find out what is actually going on inside the explosion. The observation of gravitational waves from a supernova would be as important as the discovery of neutrinos from supernova 1987a (see Figure 14) as it will provide details of the bulk motion of the mass in the explosion. In order to make a scientific programme, however, it would be necessary to observe many supernovas, which means being able to sense many galaxies, and to achieve that would require a considerable improvement in detector sensitivity over present capabilities.
The Response of Matter to Spatially Distributed Transient Energy Addition: An Asymptotic Analysis”: Part 1, Inert Gases
Published in Combustion Science and Technology, 2022
The interaction of matter and energy is fundamental to the physics occurring in systems with radically diverse length and time scales, as well as magnitudes of energy deposition. Cosmologists believe that the accelerating expansion of the universe can be attributed to the action of dark energy on the various forms of matter present (Riess et al. 1988). Supernovas, are transient astronomical events characterized by powerful and luminous stellar explosions occurring during the last evolutionary stages of a massive star or when a white dwarf is triggered into runaway nuclear fusion (Riess et al. 2004). Massive amounts of thermonuclear energy are produced within a star causing an explosion which distributes its substance into the surrounding volume of space and often produces sufficient radiation in the visible spectrum to make the supernova visible from Earth in the daytime sky (Howell 2013). Nuclear fusion may be ignited by the deposition of sufficient energy on an appropriately short time scale (Ledingham et al. 2020). A recent experiment employed powerful lasers focused on a BB sized spot of heavy hydrogen to produce a hotspot the diameter of a human hair. It generated more than 10 quadrillion watts of fusion power for 100 trillionths of a second. Lightning causes the air though which it passes in a tiny fraction of a second to be heated to temperatures estimated to be as large as 50,000 F or 28,033 K (Uman 1969) accompanied by a high pressure relative to that in the undisturbed air. The subsequent expansion of the hot gas (the piston effect (Kevorkian and Cole 1981)) is the source of a shock wave (heard as a “bang”as it passes the ear) followed by a high velocity turbulent gas flow, one source of familiar rolling thunder. The piston effect is also responsible for the blast wave generated by nuclear or conventional explosions. Thermonuclear energy deposition in the former and chemical energy in the latter are the sources of a pronounced gasdynamical response (Kassoy 2010) in the initially undisturbed gas. Instabilities occurring in rocket engine combustion chambers are examples of the dynamic response of the combustion gases to chemically generated sources of energy (Sirignano 2015).