Turbulent Inner Life of a Sunspot Uncovered

Turbulent Inner Life of a Sunspot Uncovered
http://www.scientificamerican.com/ga...ysics_20110603

"Scharmer and his colleagues found that plasma within the penumbra, the
filamentary region of the sunspot surrounding the dark central umbra, is
circulating vertically, rising or falling at various locations with
velocities of roughly one kilometer per second, or more than 3,000
kilometers per hour. (To use the human eye as an analogue, the umbra is
the pupil and the penumbra is the iris.) That rise and fall is evidence
for convection in the penumbra, a phenomenon that had been predicted by
computer simulations of sunspot dynamics but that the researchers say
had not been observationally confirmed. The convection occurs as hot
plasma rises from below, radiates away its heat, and sinks into the sun
again as it cools".

See:
http://www.scientificamerican.com/ga...ysics_20110603

On Jun 3, 11:48*pm, Sam Wormley wrote:
Turbulent Inner Life of a Sunspot Uncoveredhttp://www.scientificamerican.com/gallery_directory.cfm?photo_id=52AD...

researchers say
had not been observationally confirmed. The convection occurs as hot
plasma rises from below, radiates away its heat, and sinks into the sun
again as it cools".

Presumably the line of sight velocities are much too low to cause any
useful spectral shift regardless of the degree of instrumental
dispersion? This might have provided a means of direct measurement.

On Sat, 4 Jun 2011 09:15:05 -0700 (PDT), "Chris.B"
wrote:

Presumably the line of sight velocities are much too low to cause any
useful spectral shift regardless of the degree of instrumental
dispersion? This might have provided a means of direct measurement.

The measurement appears to have been made by direct determination of
Doppler shift looking at the 538nm C I line. With velocities on the
order of 1000 m/s, and measurement errors less than of 200 m/s, such
direct measurements would seem to be quite simple.

I believe the reason this hasn't been observed previously is related
to spatial resolution. It is only recently that solar telescopes
capable of resolving very fine structure in sunspot penumbras have
been available.

On 03/06/2011 5:48 PM, Sam Wormley wrote:
"Scharmer and his colleagues found that plasma within the penumbra, the
filamentary region of the sunspot surrounding the dark central umbra, is
circulating vertically, rising or falling at various locations with
velocities of roughly one kilometer per second, or more than 3,000
kilometers per hour. (To use the human eye as an analogue, the umbra is
the pupil and the penumbra is the iris.) That rise and fall is evidence
for convection in the penumbra, a phenomenon that had been predicted by
computer simulations of sunspot dynamics but that the researchers say
had not been observationally confirmed. The convection occurs as hot
plasma rises from below, radiates away its heat, and sinks into the sun
again as it cools".

Basically it's an upwelling of fluid from inside the Sun through a hole.
It then spills out horizontally across the face of the Sun, and we see
that as the feature we call the penumbra.

I guess this phenomenon would've been something most people would've
guessed to be the case anyways.

Yousuf Khan