Ultrahigh-energy gammas and SN 1987A.Ultrahigh-energy gammas and SN 1987A SN 1987A was a supernova in the outskirts of the Tarantula Nebula in the Large Magellanic Cloud, a nearby dwarf galaxy. It occurred approximately 51.4 kiloparsecs from Earth <ref name="hubble_heritage" />, close enough that it was visible to the naked eye. Astrophysicists An astrophysicist is a person who professionally studies and conducts research in astrophysics. Famous astrophysicists
Electromagnetic radiation emitted from excited atomic nuclei as an integral part of the process whereby the nucleus rearranges itself into a state of lower excitation (that is, energy content). . These are gamma rays with the highest energies ever detected from natural sources, 10.sup.14 electron-volts and higher. Theorists have proposed that protons accelerated in the supernova explosion would produce these gamma rays by interacting with other matter in the neighborhood. Such high-energy protons are the most common objects among the cosmic rays cosmic rays, charged particles moving at nearly the speed of light reaching the earth from outer space. Primary cosmic rays consist mostly of protons (nuclei of hydrogen atoms), some alpha particles (helium nuclei), and lesser amounts of nuclei of carbon, nitrogen, , and many astrohysicists have thought that supernovas ought to be an important source of them. Gamma rays of lower energy (around 1 million or 10.sup.6 electron-volts) have been recorded from SN 1987A (SN:1/2/88, p.5). These low-energy gamma rays apparently come from processes in the supernova that make the heavier chemical elements. However, the ultrahigh-energy ones, supposedly produced by cosmic ray cosmic ray High-speed particle (atomic nucleus or electron) that travels through the Milky Way Galaxy. Some cosmic rays originate from the Sun, but most come from outside the solar system. protons, have not appeared, though a group from the University of Adelaide Its main campus is located on the cultural boulevard of North Terrace in the city-centre alongside prominent institutions such as the Art Gallery of South Australia, the South Australian Museum and the State Library of South Australia. , Australia, searched six months of records for evidence of them. In the March 1 ASTROPHYSICAL JOURNAL LETTERS, D. Ciampa, D.J. Bird. R.W. Clay, P.G. Edwards and R.J. Protheroe state that their installation in Buckland Park, South Australia, is probably the only one located so as to be able to record showers caused by gamma rays from SN 1987A. It is an array of sensors laid out to record showers of particles triggered by the ultrahigh-energy gamma rays as they hit the atmosphere. Because the first six months after the appearance of the supernova yielded nothing, the observers say they can set rather low limits on the amount of high-energy protons produced in the supernova and their interactions with other matter in the area. |
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