Massive stars are inherently violent creatures-burning, shake, rotate, and In turn, while created and maintained constantly changing magnetic field strength almost unfathomable.
And finally, explode, littering the universe with the elements of life as we know hydrogen, oxygen, carbon, etc. Everything including us is the result of the violent death of a star. "We are stardust, we are golden, we are carbon billions of years old, "says the song" Woodstock "by Crosby, Stills, Nash and Young.Y any star makes this better than those that someday will become supernovae after the collapse of its core , ie stars more than eight masses solares.Sin However, the evolution and nature of this source of elements is still a mystery, one of the great unsolved problems of astrophysics. But perhaps not for long unresolved. A team led by Tony Mezzacappa Oak Ridge National Laboratory (ORNL) is getting closer to explaining the origins of CCSN explosions (supernova core-collapse) with the help of Jaguar, a Cray XT5 supercomputer located at the Oak Ridge ORNL Leadership Computing Facility.
In essence, said Eirik EnDev, lead author of the recent work of the team, the researchers want to know how these magnetic fields are created and how they affect the explosions of these massive stars. A recent set of simulations allowed the team to address some of the most fundamental questions surrounding the CCSNs magnetic fields. Their findings were published in The Astrophysical Journal. Unravelling the mystery surrounding the powerful magnetic fields of these stars, ultimately, the Researchers may explain much about why these giant stellar firecrackers become elements.
In an effort to locate the source of magnetic fields, the team simulated the progenitor of a supernova or star in their pre-supernova phase, using the Jaguar for many hours, the fastest supercomputer in the nation. The process revealed that we still have much to learn when it comes to how to operate these stellar wonders. Once
collapsed remnants of a supernova are commonly known as pulsars , and with respect to magnetic fields, pulsars are the best players in the stellar community. These highly magnetized neutron stars rapidly spinning their name from their similarity to the beam pulse produced by the headlights that turn. This rotation is thought to be a major factor in determining the intensity of the magnetic field of a pulsar in the field as a star rotates faster stronger magnetic field.
representation fluid volume below the shock wave from the supernova during the phase called SASI (standing accretion shock Instability). The velocity of fluid flow traces intricate designs in EnDev simulación.Crédito.Eirik .
The supernova progenitor stars tend to be slower rotation. However, these progenitor simulations revealed a strong mechanism for magnetic field generation, which contradicts the accepted theory that the rotation could be a main driver.
Interestingly, this finding is based on previous work by the team, along with the latest simulations revealed that the culprit behind the rotation of the pulsar is also responsible for their magnetic fields. The previous simulations, whose results were published under the title "Pulsar spins from an Instability in the accretion shock of supernovae (see here ) in the January 2007 in Nature, showed that a phenomenon known as "a spiral" occurs when the expanding shock wave from a supernova core is sealed in a stage known as unstable accretion permanent shock (SASI). As the expanding shock wave drives the supernova explosion is a pause, the area outside the boundaries of the shock wave enters the interior, creating vortices that not only start the rotation of the star, but also cut and stretch their magnetic fields.
This new revelation means two things for astronomers: first, that any rotation serve as a key driver for the magnetism of a supernova is created through "a spiral", and secondly, that not only "a spiral" leading the rotation, but can also determine the intensity of the fields a magnetic pulsar.
Another important finding of the team's simulations is that the flow of cutting the SASI, or when the counter-rotating layers of the star rub against one another during the event SASI, is highly susceptible to turbulence, which also can extend and strengthen the magnetic fields of the progenitor, similar to the expansion of a spring.
These two results together indicate that magnetic fields can CCSN be efficiently generated by a somewhat unexpected source: cut flow-induced turbulence roiling the innermost core of the star. "We found that from a magnetic field similar to what we thought was in a supernova progenitor, this turbulent mechanism is able to increase the intensity of the pulsar's magnetic field, "said EnDev.
The team used the general astrophysics simulation system (GENASIS) to study the evolution of the magnetic field of the progenitor. Genasis, under development by Christian Cardall, Budiardia Reuben EnDev and Mezzacappa at ORNL and Pedro Marronetti at Florida Atlantic University, has a new approach for the transport of neutrinos and the severity and less than its counterpart earlier approaches, which were supposed to CCSNs perfectly spherical.
The simulations essentially resolved a number of magnetohydrodynamic equations, or equations that describe the properties of electrically conducting fluids. After the initial conditions established, the team made several models with high and low resolutions, with higher resolution models taking more than one month completarse.Inicialmente, EnDev said, which were carried out at lower resolutions, but produced little significant activity. However, as intensified resolution, things got interesting.
The model starts at 4000 nuclei, EnDev said, but as the stars become more chaotic with turbulence and other factors, the simulations are scaled up to 64,000 cores, giving the team a more realistic picture of magnetic activity in CCSN. He added that the fact that the solution time for these vastly varying sizes of work is the same is due to policy programming Jaguar tail which is a "big advantage." "The facilities here are excellent," said EnDev, adding that the high-performance storage system is very important for the research team, when a model produces hundreds of terabytes of data. "We have also received much help from the display device, especially Toedter Ross, and link the group to OLCF, Bronson Messer."
The team will soon incorporate sophisticated neutrino transport and relativistic gravity, which will give a more realistic picture of the CCSNs. However, to make a powerful source of economic, EnDev said, it will be necessary to employ an adaptive mesh. And, of course, require the computing power of Jaguar.
This latest discovery is a step closer to unraveling the mysteries of the CCSNs. As you follow GENASIS evolve, the team will be able investigate these important stellar cataclysms to unprecedented levels, so science is one step closer to a fundamental understanding of our universe.
read the study HERE
source of information:
http://www.physorg.com/news/2011-03-exploring-magnetic-personalities- stars.html
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