The soft X-rays emitted during solar flares are thermal radiation, released by virtue of the intense heat and dependent upon the random thermal motions of very hot electrons.
At such high temperatures, the electrons are set free from atoms and move off at high speed, leaving the ions primarily protons behind. When a free electron moves through the surrounding material, it is attracted to the oppositely charged protons. The electron is therefore deflected from a straight path and changes its speed during its encounter with the proton, emitting electromagnetic radiation in the process Fig. Scientists use measurements of the flaring X-ray power to infer the density of the electrons emitting the bremsstrahlung.
Observations from the Yohkoh spacecraft, launched on 30 August , have confirmed and extended this understanding of X-ray flares. According to this picture, solar flare energy release occurs mainly during the rapid, impulsive phase, when charged particles are accelerated and hard X-rays are emitted. The subsequent, gradual phase, detected by the slow build up of soft X-rays, is viewed as an atmospheric response to the energetic particles generated during the impulsive hard X-ray phase.
With Yohkoh, the double-source, loop-footpoint structure of impulsive hard X-ray flares was confirmed with unprecedented clarity. It established a double-source structure for the hard X-ray emission of roughly half the flares observed in the purely non-thermal energy range above 30 keV. The other half of the flares detected with Yohkoh were either single sources, that could be double ones that are too small to be resolved, or multiple sources that could be an ensemble of double sources.
As subsequently discussed, a third hard X-ray source is sometimes detected near the apex of the magnetic loop joining the other two; this loop-top region marks the primary energy release site and the location of electron acceleration due to magnetic interaction. Two white-light emission patches were also detected by Yohkoh during at least one flare, at the same time and place as the hard X-ray sources Fig.
This shows that the rarely-seen, white-light flares can also be produced by the downward impact of non-thermal electrons, and demonstrates their penetration deep into the chromosphere. Protons and heavier ions are accelerated to high speed during solar flares, and beamed down into the chromosphere where they produce nuclear reactions and generate gamma rays, the most energetic kind of radiation detected from solar flares.
Like X-rays, the gamma rays are totally absorbed in our air and must be observed from space. The protons slam into the dense, lower atmosphere, like a bullet hitting a concrete wall, shattering nuclei in a process called spallation. The nuclear fragments are initially excited, but then relax to their former state by emitting gamma rays.
Other abundant nuclei are energized by collision with the flare-accelerated protons, and emit gamma rays to get rid of the excess energy Fig. The excited nuclei emit gamma rays during solar flares at specific, well-defined energies between 0.
One MeV is equivalent to a thousand keV and a million electron volts, so the gamma rays are ten to one hundred times more energetic than the hard X-rays and soft X-rays detected during solar flares. The radio emission of a solar flare is often called a radio burst to emphasize its brief, energetic and explosive characteristics. Although the radio emission of a solar flare is much less energetic than the flaring X-ray emission, the solar radio bursts provide an important diagnostic tool for specifying the magnetic and temperature structures at the time.
They additionally provide evidence for electrons accelerated to very high speeds, approaching that of light, as well as powerful shock waves. Radio bursts do not occur simultaneously at different radio frequencies, but instead drift to later arrival times at lower frequencies.
This is explained by a disturbance that travels out through the progressively more rarefied layers of the solar atmosphere, making the local electrons in the corona vibrate at their natural frequency of oscillation, called the plasma frequency. With an electron density model of the solar atmosphere Fig.
Electron beams that produce type III radio bursts are moving at velocities of up to half the velocity of light, or million meters per second. Outward moving shock waves that generate type II radio bursts move at a slower speed, at about a million meters per second. Australian radio astronomers pioneered this type of investigation in the s, using swept-frequency receivers to distinguish at least two kinds of meter-wavelength radio bursts. Designated as type II and type III bursts, they both show a drift from higher to lower frequencies, but at different rates.
The test also helped the U. Such advances helped make a treaty to ban nukes in space more realistic. But there are other potent sources of radiation in outer space.
There is a very small chance, Sibeck says, that a solar flare at just the right moment could hit the planet with a similar amount of radiation. The largest geomagnetic storm ever recorded , called the Carrington Event, hit Earth in It caused auroras over Australia and gave electrical shocks to telegraph operators in America. If a similar storm hit today, the consequences would be much more serious than downed telegraph lines. Things in your house, things in your car, communications.
In the unlikely event another nuclear bomb goes off in space, Geoff Reeves, a research fellow at Los Alamos National Laboratory in New Mexico, has been working on a quick way to get rid of radiation belts made from nuclear blasts. In his design, a transmitter mounted on a satellite hits the trapped radiation with specialized AM radio waves, which nudge the charged particles lower into the atmosphere, where they would be harmlessly absorbed. All rights reserved.
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Animals Wild Cities Wild parakeets have taken a liking to London. Even a few fractions-of-a-second afterwards, the rapid, adiabatic expansion of the gas inside causes the temperature to drop dramatically.
But in a multi-stage atomic bomb, a small fission bomb is placed around material that's suitable for nuclear fusion. The nuclear explosion compresses and heats the material inside, achieving the high temperatures and densities necessary to ignite that runaway nuclear reaction.
When nuclear fusion occurs, even greater amounts of energy are released, epitomized by the Soviet Union's detonation of the Tsar Bomba. The Tsar Bomba explosion was the largest nuclear detonation ever to take place on Earth, and is It's true: the hottest hydrogen bombs, leveraging the power of nuclear fusion, have indeed achieved temperatures of hundreds of millions of degrees Celsius. Or kelvin, whose units we'll use from now on.
The majority of the Sun's volume is composed of the radiative zone, where temperatures increase from the thousands into the millions of K. At some critical location, temperatures rise past a threshold of around 4 million K, which is the energy threshold necessary for nuclear fusion to begin.
As you go closer towards the center, the temperature rises and rises, to a peak of 15 million K in the very center. This is the hottest temperature achieved in a star like our Sun. While the outer photosphere of the Sun may be at merely 6, K, the inner core reaches temperatures as high as 15,, K. And it's a reasonable question to ask. If you look at total energy, there's no comparison. The aforementioned Tsar Bomba, the largest nuclear explosion ever to take place on Earth, gave off the equivalent of 50 megatons of TNT: petajoules of energy.
This cutaway showcases the various regions of the surface and interior of the Sun, including the As time goes on, the helium-containing region in the core expands and the maximum temperature increases, causing the Sun's energy output to increase.
When our Sun runs out of hydrogen fuel in the core, it will contract and heat up to a sufficient degree that helium fusion can begin. With such enormous differences in energy, it might seem like a mistake to conclude that an atomic bomb's temperature is many times higher than the center of the Sun.
And yet, it isn't all about energy. It's not even about power, or the energy released in a given amount of time; the Sun has the atomic bomb beaten by a wide margin in that metric as well.
Neither energy nor energy-per-unit-time can successfully explain why atomic bombs can reach higher temperatures than the Sun's core. But there is a physical explanation, and the way to see it for yourself is to think about the volume of the Sun. Yes, there's an enormous amount of energy being emitted, but the Sun is huge.
If we restrict ourselves to the core, even to the innermost, hottest region of the core, we're still talking about enormous volumes of space, and that makes all the difference. Despite things like flares, coronal mass ejections, sunspots, and other complex physics occurring in Because the Sun is so enormous — its diameter is approximately 1,, kilometers, or over times the diameter of Earth — the total amount of energy and power it produces is spread out over an enormous volume.
The key thing to look at isn't just mass, energy, or power, but the density of those quantities. The anatomy of the Sun, including the inner core, which is the only place where fusion occurs.
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