Word: shells
(lookup in dictionary)
(lookup stats)
Dates: during 1980-1989
Sort By: most recent first
(reverse)
...Looking for America), has a firm hold on the fundamentals of nuclear physics. He describes the first millisecond of the atomic age in New Mexico with eerie precision: "The firing circuit closed; the X-unit discharged; the detonators at 32 detonation points simultaneously fired; they ignited the outer lens shells of Composition B; the detonation waves separately bulged, encountered inclusions of Baratol, slowed, curved, turned inside out, merged to a common inward-driving sphere; the spherical detonation wave crossed into the second shell of solid fast Composition B and accelerated; hit the wall of dense uranium tamper and became...
...diamonds, Anders suggests, came from red supergiant stars that threw off their outer coats, forming a gas shell. As the star's shell expanded outward and cooled, the carbon in it condensed and crystallized, forming diamonds. Later, when the star exploded, it created xenon that shot from the star's outer layers and caught up with the diamonds. "It's like the tortoise and hare," says Anders. "The xenon atoms overtake the diamonds and shoot right through them, becoming very securely locked...
Some astronomers are in less of a hurry, figuring that the best is yet to come. Says Woosley: "Once the photosphere ((the supernova's luminous surface layer)) is gone, that's when it gets interesting." When that shell thins out, months or years from now, astronomers will be able to look inside and "see" the newly born, rapidly spinning neutron star, but with a radio telescope rather than the optical kind...
...last week scientists had already amassed more data than they could immediately analyze, confirming some theoretical predictions and making several observations that for the time being puzzled everyone. Earliest readings showed that the shell of gases expanding around 1987A was initially traveling outward at nearly 10,000 miles per second. Since then the color of the supernova has been changing from blue to red much faster than expected. "That change is five to ten times faster than other supernovas," says Robert Williams, director of the U.S.-financed Cerro Tololo Inter-Observatory in Chile. This phenomenon indicates that the rapid expansion...
...core contracts, however, its internal pressures will rise, forcing the temperature rapidly back up again until the intense heat ignites the unfused hydrogen gas surrounding the core. The interior of the sun will now be hotter than ever, a dense core of incandescent helium surrounded by a thin shell of hot, fusing hydrogen. Over the next few hundred million years, heat from the core will drive surface layers of the sun so far outward that they will cool to about two-thirds of the current 6,000 degrees C surface temperature, and redden. The sun will have become...