Gamma Rays Confirm Exploding Stars Create Heavy Matter In Universe
LOS ANGELES (AP) _ Scientists say they have detected gamma rays from a giant supernova, confirming a long-held theory that all the heavy elements in the universe were produced by such ancient, exploding stars.
″Earth is the way it is because it was formed out of material ejected by some earlier supernova,″ said astrophysicist Tom Prince of the California Institute of Technology in Pasadena. ″Just about everything we see around us - such as the iron in your car - was thrown out from a supernova.″
″We wouldn’t have life as we know it without the production of these heavy elements (such as nickel, cobalt and iron) in supernovas,″ said astrophysicist Gerald Share of the Naval Research Laboratory in Washington.
And without iron in Earth’s core, the planet would lack the magnetic field that ″protects us from being destroyed by radiation″ from space, Share said Friday.
The discovery that Supernova 1987A emits gamma rays, similar to radiation used to treat cancer patients, was revealed over the past nine days by three teams of scientists working for a NASA program aimed at studying the exploding star about 160,000 light years, or 1 million trillion miles, from Earth.
The gamma rays, detected by instruments aboard a satellite and two balloons, are emitted when radioactive cobalt-56 in the supernova changes into iron.
The journal Science said last month that detection of gamma rays from the supernova would verify ″astronomers’ long-held belief ... that virtually all the iron in the universe, virtually all the other heavy elements in the universe, and indeed virtually all the material in Earth itself, are the products of long-ago supernovas.″
″The detection of gamma rays was crucial to confirming the theory,″ the National Aeronautics and Space Administration said.
While several supernovas are detected each year, Supernova 1987A’s gamma rays are the first ever detected from an exploding star because the supernova is closer to Earth than any observed since German astronomer Johannes Kepler saw one in 1604.
The newborn universe likely contained mostly the lightest elements, hydrogen and helium, which later fused inside stars to form the carbon, nitrogen, oxygen and other elements that make up living organisms. Elements as heavy as aluminum are believed to have formed in massive stars.
For at least 20 years, scientists theorized that only supernovas are hot enough for thermonuclear fusion of lighter elements to produce nickel, cobalt, iron and heavier elements.
While elements as ″light″ as silicon in glass and rocks can form in stars, only supernovas can kick them into space so they can form planets, Prince said.
The gamma rays first were detected in August by a sensor aboard NASA’s Solar Maximum Mission satellite. The detection was only recently confirmed. The sensor was operated by a team that included the University of New Hampshire’s Edward Chupp; Steven Matz and Share at the Navy lab; and scientists at West Germany’s Max Planck Institute for Extraterrestrial Physics.
The two other teams detected the rays using instruments aboard two balloons that flew above Alice Springs, Australia, in October and November. One team was headed by William Sandie, at California’s Lockheed Palo Alto Research Laboratory, and Gerald Fishman at NASA’S Marshall Space Flight Center in Alabama.
Prince headed the third team.
Supernova 1987A formed about 160,000 years ago from the explosion of a star named Sanduleak-69.202. Light from the blast reached Earth only last February, greatly exciting scientists.
The Caltech and Lockheed researchers revealed their gamma-ray findings last Monday during a scientific meeting in Washington. The Solar Max results were announced Dec. 11 in a circular issued by the Central Bureau for Astronomical Telegrams in Cambridge, Mass.