- 4118 -
SUN - high energy flares? Scientists discover the highest-energy
light coming from the sun. The sun is
more surprising than we knew.
Astronomers thought we had this star figured out, but that's not the
case.
-
-------------- 4118 - SUN - high energy flares?
- The new discovery of the highest-energy
light ever observed from the sun has astronomers surprised. This type of high energy light, known as
“gamma rays”, is surprisingly bright.
-
- Although the high-energy light doesn't
reach the Earth's surface, these gamma rays create telltale signatures that
were detected with the “High-Altitude Water Cherenkov Observatory”, or HAWC
observartory.
-
- In this particular energy, other
ground-based telescopes couldn't look at the sun because they only work at
night, HAWC operates 24/7. It is working
differently from conventional telescopes.
Rather than a tube outfitted with glass lenses, HAWC uses a network of
300 large water tanks, each filled with about 200 metric tons of water. The
network is nestled between two dormant volcano peaks in Mexico, more than
13,000 feet above sea level.
-
- From this vantage point, it can observe the
aftermath of gamma rays striking air in the atmosphere. Such collisions create
what are called “air showers”, which are a bit like particle explosions that
are imperceptible to the naked eye.
-
- The energy of the original gamma ray is
liberated and redistributed among new fragments consisting of lower energy
particles and light. It's these particles and the new particles they create on
their way down that HAWC can "see."
-
- When the shower particles interact with
water in HAWC's tanks, they create “Cherenkov radiation” that can be detected
with the observatory's instruments. They
began collecting data in 2015. In 2021, the team had accrued enough data to
start examining the sun's gamma rays with sufficient scrutiny.
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- After looking at six years' worth of data,
out popped this excess of gamma rays.
The sun gives off a lot of light spanning a range of energies, but some
energies are more abundant than others.
Through its nuclear reactions, the sun provides a ton of visible
light. This form of light carries an
energy of about 1 “electron volt”.
-
- The gamma rays that HAWK observed had about
1 trillion electron volts, or 1 tera electron volt, abbreviated 1 TeV. Not only
was this energy level surprising, but so was the fact that they were seeing so
much of it.
-
- In the 1990s, scientists predicted that the
sun could produce gamma rays when high-energy cosmic ray, particles accelerated
by a cosmic powerhouse like a black hole or supernova, smash into protons in
the sun. But, based on what was known about cosmic rays and the sun, the
researchers also hypothesized it would be rare to see these gamma rays reach
Earth.
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- At that time there wasn't an instrument
capable of detecting such high-energy gamma rays. The first observation of
gamma rays with energies of more than a billion electron volts came from NASA's
Fermi Gamma-ray Space Telescope in 2011.
-
- Over the next several years, the Fermi
mission showed that not only could these rays be very energetic, but also that
there were about seven times more of them than scientists had originally
expected. And it looked like there were gamma rays left to discover at even
higher energies.
-
- When a telescope launches into space,
there's a limit to how big and powerful its detectors can be. The Fermi
telescope's measurements of the sun's gamma rays maxed out around 200 billion
electron volts.
-
- Now, for the first time, the measurements
have shown that the energies of the sun's rays extend into the TeV range, up to
nearly 10 TeV, which does appear to be the maximum.
-
- This discovery creates more questions than
answers. Solar scientists will now scratch their heads over how exactly these
gamma rays achieve such high energies and what role the sun's magnetic fields
play in this phenomenon.
-
- This shows that HAWC is adding to our
knowledge of our galaxy at the highest energies, and it's opening up questions
about our very own sun. "It's making us see things in a different light.
Literally."
-
-
August 13, 2023 4118
- SUN - high
energy flares? 4118
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Sunday, August 13, 2023 ---------------------------------
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