Microflares on Sun Could Play Major Role In Heating Corona

In article , Ron Baalke
writes
Microflares on Sun could play major role in heating corona
University of California Berkeley News Release
July 21, 2003

The Sun's big, bright, explosive flares are the attention grabbers,
but tiny, more numerous microflares may have nearly as much influence
on the solar atmosphere, according to new data from the University of
California, Berkeley's RHESSI satellite.

Solar flares, the largest explosions in the solar system, propel energetic
particles into space and are thought to be the main source of heat pumping the
Sun's outer atmosphere to a few million degrees Celsius - hotter than the
surface itself.

This is based on the idea that indications of ultra high temperature are
thermal characteristics. A more rational explanation is that these
characteristics are caused by the re-combination of protons and positive
ions with relativistic electrons, as described in Dr Laszlo
Kortvelyessy's book 'The Electric Universe'. See Observatory review in
website
http:/www.brox1.demon.co.uk/sun2.htm
(New Light on the Sun)


RHESSI, launched by NASA in February 2002 to study X-ray and gamma-ray
emissions from flares, has observed more than 10,000 microflares in the past
year and a half. These microflares are identified by the hard X-rays they emit,
which RHESSI is able to detect with 10 to 500 times the sensitivity of any
previous instruments flown in space.

These X-ray observations show that microflares are merely smaller versions of
their larger cousins, Lin said. Some astronomers have suggested that
microflares may be mainly thermal events, heating the Sun but not accelerating
particles like larger flares. If that were the case, they would produce more
low-energy soft X-rays than high-energy hard X-rays. But they do not.

"We've noticed that microflares are very similar to big flares. In big flares,
a lot of the energy, perhaps most of it, comes out in accelerated particles -
electrons, protons and heavy nuclei," Lin said. "We are finding the same to be
true of microflares."

Interestingly, a subset of microflares appears to be a different animal
entirely
and responsible for a type of radio burst from the Sun studied intensively by
pioneering Australian radio astronomer Paul Wild in the 1960s and 1970s.
These so-called Type III bursts are characterized by radio signals that
decrease in frequency, like the whistle from a departing train.

RHESSI has seen many Type III bursts, and they appear to be associated with
microflares that do very little heating of the solar atmosphere. Instead, the
stream of high-speed particles they produce seems to jet unchecked out of the
Sun at speeds up to one-third the speed of light, exciting radio
oscillations at
lower and lower frequencies as the particles pass through lower and lower
density plasma.

"This probably has to do with the magnetic field in the region around the
microflare, since particles are pretty much tied to the field lines and
have to
run along them," Lin said. "We think that for normal microflares, the particle
acceleration occurs in a closed magnetic region so the electrons can't
get away;
they do more heating that way. In Type III bursts, the electrons are
accelerated
in an open magnetic field, and they have an easy way to escape, so they do less
heating in the corona."

Aside from RHESSI's numerous observations of microflares, the satellite's
X-ray and gamma-ray instruments have also captured several large flares.
These have allowed the RHESSI team to investigate the relationship between
flares and coronal mass ejections (CME), which are another type of large
stellar explosion that sends shock waves into space. One conclusion, Lin said,
is that the fastest coronal mass ejections - those moving at 1 to 5
million miles
per hour (1.6 to 8 million kilometers per hour) - are linked directly to solar
flares.

"With RHESSI, we can image the location of a flare's initial release of energy
and accelerated particles," Lin said. "When we look at extremely big and fast
coronal mass ejections and extrapolate back to the Sun, we find that at
the very
point where the coronal mass ejection is initiated, that is exactly where the
flare energy release happened. The flare starts everything off."

These largest of the mass ejections are the ones that have the greatest effect
on Earth, exciting geomagnetic storms that can cause power outages and
damage communications satellites. The shock wave from coronal mass
ejections also produces energetic particles that pose a hazard to
satellites and
astronauts.

"If we understood the process, we could begin predicting when coronal mass
ejections should happen," Lin said. "We're still a long way from that, but it
makes it extremely interesting to discover the relationship between flares and
coronal mass ejections."

It is still unclear whether other types of coronal mass ejections are
related to
solar flares, he said.

Both flares and coronal mass ejections are produced by the roiling magnetic
fields in the surface of the star. As the surface churns, magnetic field lines
get twisted like rubber bands. When the tension becomes too great, they break,
snapping and flinging charged particles outward in a solar flare.

Magnetic field lines are just a mathematical concept invented by Faraday
to represent the strength and direction of a magnetic field. The idea
that they are real and twist like rubber bands and break with immense
release of energy is a crazy non-scientific idea. A far better
explanation is in terms of electrical charging and sudden discharge like
terrestrial lightning on an immensely greater scale in the Sun.

Flares can trigger coronal mass ejections, which are massive rising bubbles of
plasma entangled with the magnetic field. But some mass ejections seem
unrelated to flares, Lin said. One possible explanation is that these come from
magnetic fields that kink as they twist, so the magnetic field
intensity doesn't
get compressed enough to explode into a flare.

Kink as they twist? Sounds like a joke.

Electrical discharges form filaments which may be deflected by magnetic
fields.



--
Eric Crew