Study Proposes New Interpretation For Solar Emissions
Hello
reader!
It
follows an article published day (09/10) in the english website of the Agência
FAPESP noting that a Study conducted by researchers from Brazil and the United States proposes new interpretation for Solar Emissions.
Duda
Falcão
Articles
Study Proposes New Interpretation
For Solar Emissions
By José
Tadeu Arantes
September
10, 2014
(Image: NASA)
A study conducted by researchers
from Brazil and the
United States explains
radiation at frequencies close to far-infrared
produced
by eruptions of the Sun.
|
Agência FAPESP – An explanation for the high-frequency
radiation produced by solar emissions has just been proposed based on a
physical process observed in laboratory particle accelerators. The article detailing the study “The contribution of
microbunching instability to solar flare emission in the GHz to THz range of
frequencies,” by John Michael Klopf of the College of William and Mary
(Williamsburg, Virginia, United States) and Pierre Kaufmann, Jean-Pierre Raulin
and Sérgio Szpiegel from Mackenzie Presbyterian University, was published
August 10, 2014 in The Astrophysical Journal.
The study was conducted under the FAPESP-funded thematic project “Solar activity emissions from sub-millimeter waves to infrared (SIRA).”
The proposed explanation was substantiated through a computer simulation
that was based on the physical processes that take place in laboratory particle
accelerators. The simulation investigated how these processes might occur in a
context governed by solar parameters. “The results proved to be quite
convincing. It was one of those rare occasions in which laboratory simulation
of space plasma was successful,” Kaufmann told Agência FAPESP.
The physical process in question is that of coherent synchrotron
radiation, which can occur when electron beans are accelerated until they reach
speeds close to the speed of light. This radiation is produced at the same time
as the well-known incoherent synchrotron radiation, generated by the same
beams, and it depends upon the interaction of the electrons in the magnetic
fields.
If the waves that describe the electrons remain in phase coherence, upon
releasing energy, all the electrons would do so at the same time. This is what
constitutes coherent radiation, characterized by the emission of high-intensity
energy pulsations.
“In the accelerators, the particles are artificially accelerated through
magnetic fields. On the Sun, the process is associated with sunspots, which are
magnetic poles,” the Mackenzie researcher explained.“Particles are confined
largely to the region situated above the sunspot in the solar atmosphere.
Typically, this confinement tends to disappear in two Earth months, which is
how long sunspots last, supported by the period of the Sun’s rotation,”
Kaufmann said. “Because of some yet-unknown mechanism, it could be that instead
of becoming undone, the particle plasma is accelerated and expelled from the
Sun as an eruption called a flare because the region emits large quantities of
radiation in a very short period.”
To have an idea of the magnitude of the phenomenon, just consider that
the number of particles involved in a solar eruption is estimated at 10 to the
30th power (the numeral 1 followed by 30 zeros, i.e., one nonillion,
or one thousand billions of billions of billions). The energy released is
approximately 100 billion times more than that of the atomic bomb the United
States dropped on the Japanese city of Hiroshima during World War II.
The electromagnetic radiation generated by the solar eruptions has been
studied since the 1950s. Scholars, however, had identified only that radiation
in the radio and microwave frequency bands. Nearly a decade ago, however,
thanks to a Brazilian radio telescope installed in the Argentine Andes, it was
discovered that the eruptions also emitted much higher frequencies, close to
far-infrared, also known as the terahertz band.
“This introduces a huge problem in terms of interpretation,” Kaufmann
commented. “To explain this type of emission, simultaneous with the microwave
band of emissions, we’re now proposing the analogy with coherent synchrotron
radiation, previously observed in particle accelerators.”
The explanation recognizes the possibility that electrons group together
in similar states of energy and phase, which may occur, for example, when
electron beams propagate through regions affected by irregular magnetic fields.
“The agglomerations of electrons may then suddenly emit synchronic radiation
together, coherently. The phenomenon is known as microbunching,” the researcher
reported.
According to Kaufmann, physicist John Michael Klopf, first author of the
article, is a specialist in accelerator physics and has worked for many years
at the Thomas Jefferson National Accelerator Facility, commonly known as the
Jefferson Lab, a U.S. national laboratory, one of the first to detect the
phenomenon of microbunching.
“The magnetic fields in the solar regions where the eruptions occur are
very complex and could easily give rise to bunches of electrons similar to
those detected in the laboratories,” the researcher said.
Source: English
WebSite of the Agência FAPESP
Comentários
Postar um comentário