The
obse vatio s
we e
made
with
the
Da iel
K.
I ouye
Sola
Telescope
(DKIST),
a
powe ful
4-met e
class
sola
telescope
ope ated
by
the
US
Natio al
Scie ce
Fou datio .
The
Su
may
appea
to
us
o
Ea th
as
a
glowi g
ball
of
plasma,
but
its
su face
is
fa
mo e
active
a d
tu bule t
tha
it
looks,
which
has
bee
p ove
time
a d
agai
th ough
esea ch.
Acco di g
to
a
latest
epo t
by
Natu e,
obse vatio s
f om
the
wo ld’s
la gest
sola
telescope
have
ow
p ovided
a
i c edibly
detailed
view
of
the
Su ‘s
su face,
showi g
ti y
swi li g
st uctu es
that
could
help
scie tists
u de sta d
how
e e gy
a d
mag etic
fields
flow
th ough
the
sola
atmosphe e.
The
a ticle
clea ly
me tio s
that
the
obse vatio s
we e
made
with
the
Da iel
K.
I ouye
Sola
Telescope
(DKIST),
a
powe ful
4-met e
class
sola
telescope
ope ated
by
the
US
Natio al
Scie ce
Fou datio .
It
could
exami e
pa ts
of
the
Su
o
the
o de
of
19
kilomete s,
letti g
esea che s
see
featu es
that
we e
too
small
fo
sola
telescopes
to
detect
befo e.
A
close
look
at
the
Su
The
photosphe e
–
the
visible
su face
of
the
Su
–
is
eve
still.
It
is
p ove
to
have
hot
plasma
which
ises,
cools,
a d
the
si ks
agai
i
a
p ocess
k ow
as
co vectio .
These
moveme ts
c eate
patte s
like
boili g
wate .
Mag etic
fields
a e
also
p ese t
ac oss
the
whole
sola
su face.
They
i te act
with
these
tu bule t
plasma
flows
c eati g
a
eve -cha gi g
e vi o me t.
Some
of
the
smallest
details
of
this
i te actio
had
bee
hidde
u til
ow
because
existi g
telescopes
could
ot
see
them
clea ly.
But
DKIST
has
cha ged
that
view.
The
high- esolutio
images
show
that
the
edges
whe e
mag etic
egio s
meet
the
su ou di g
plasma
a e
ot
smooth.
Rathe ,
they
a e
filled
with
little
vo tices
a d
swi ls.
Mi iatu e
vo tices
o
the
Su ’s
su face
Whe
scie tists
looked
at
a
se ies
of
images,
they
saw
vo tices
fo mi g
a d
cha gi g
a ou d
mag etic
a eas.
The
smallest
st uctu es
we e
ea
DKIST’s
theo etical
limit
of
esolutio ,
about
19
kilomete s.
A
study
of
47
vo tices
showed
they
ge e ally
ma ifested
at
oughly
65
kilomete s
apa t
a d
i dividual
vo tices
a ged
f om
a ou d
25
to
170
kilomete s
i
size.
They
also
seemed
to
move
ac oss
the
Su
at
speeds
betwee
about
0.67
a d
3
kilomete s
pe
seco d.
Acco di g
to
scie tists,
these
small
swi ls
a e
impo ta t
because
they
a e
associated
with
a
physical
p ocess
called
the
Kelvi –Helmholtz
i stability,
o
KHI.
What
is
Kelvi -Helmholtz
i stability?
The
Kelvi –Helmholtz
i stability
is
a
i stability
that
occu s
whe
two
laye s
of
fluid
o
plasma
a e
movi g
past
each
othe
at
diffe e t
speeds.
The
Kelvi –Helmholtz
i stability
is
a
i stability
that
occu s
whe
two
laye s
of
fluid
o
plasma
a e
movi g
past
each
othe
at
diffe e t
speeds.
The
diffe e ce
i
speed
p oduces
a
st o g
shea .
This
shea
ca
make
the
bou da y
betwee
the
laye s
u stable,
developi g
waves
a d
swi ls.
Acco di g
to
scie tists,
a
familia
example
is
the
wave-like
patte
that
sometimes
occu s
whe
wi d
blows
ac oss
the
su face
of
wate .
Scie tists
have
p edicted
that
simila
i stabilities
may
occu
o
the
Su .
Howeve ,
thei
ve y
small
size
made
it
difficult
to
see
them
di ectly.
The
ew
obse vatio s
f om
DKIST
show
these
i stabilities
to
be
commo
a ou d
mag etic
egio s
o
the
sola
su face.
How
mag etic
fields
c eate
co ditio s
The
esea che s
fou d
that
the
Su ’s
o mal
co vective
flows
ca
d ift
towa d
locatio s
with
st o g
mag etic
fields.
The
bou da y
betwee
the
flows
ca
show
a
sha p
velocity
diffe e ce
whe
the
flows
meet
mag etic
egio s.
This
st o g
diffe e ce,
o
velocity
shea ,
p ovides
the
co ditio s
ecessa y
fo
the
g owth
of
the
Kelvi -Helmholtz
i stability.
The
mag etic
field
i
the
obse ved
egio
is
mai ly
ve tical
a d
the
plasma
flows
a e
mai ly
ho izo tal,
so
the
mag etic
field
does
ot
completely
supp ess
the
i stability.
This
leads
to
ma y
small,
fast-cha gi g
vo tices
a ou d
mag etic
co ce t atio s.
The
discove y
is
co fi med
by
compute
simulatio s
The
scie tists
checked
that
what
they
saw
o
the
telescope
was
i deed
Kelvi -Helmholtz
i stabilities
by
compa i g
the
images
f om
the
telescope
with
detailed
compute
simulatio s
of
the
Su ’s
atmosphe e.
The
simulatio s
esulted
i
vo tices
havi g
a
ve y
simila
shape
a d
behavio
to
those
obse ved
by
DKIST.
The
simulated
vo tices
had
simila
sizes,
g owth
ates
a d
moveme t
speeds.
The
good
ag eeme t
betwee
obse vatio s
a d
simulatio s
gives
esea che s
mo e
co fide ce
that
the
swi li g
st uctu es
a e
i deed
caused
by
Kelvi -Helmholtz
i stabilities.
Why
this
discove y
matte s
Acco di g
to
scie tists
i volved
i
the
p ocess,
the
fi di g
could
help
them
u de sta d
how
the
Su
t a spo ts
mass,
e e gy,
mome tum
a d
mag etic
fields
th ough
its
atmosphe e.
The
p ocesses
a e
closely
elated
to
the
behavio
of
active
egio s
o
the
Su
a d
could
eve tually
help
them
to
bette
u de sta d
sola
activity.
The
vo tices
ca
also
twist
a d
b aid
the
mag etic
field
li es.
Such
p ocesses
ca
affect
the
sto age
a d
elease
of
mag etic
e e gy
i
the
sola
atmosphe e.
Most
impo ta t,
the
pictu es
eveal
that
the
su face
of
the
Su
is
much
mo e
dy amic
a d
complex
at
small
scales
tha
p evious
images
had
suggested.
DKIST
is
givi g
scie tists
a
ew
view
of
the
tu bule t
p ocesses
that
powe
the
Su ’s
mag etic
e vi o me t,
esolvi g
st uctu es
o ly
te s
of
kilomete s
ac oss.Images
Cou tesy:
istock
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