Transcript Model of the Solar Interior - Onondaga Community College

Model of the Solar Interior
The theoretical data
presented here is the basis
of the Two–Layer Model of
Stars: Core & Envelope
Traditional models of the Solar Interior
present three regions: The Core, The
Radiative Zone and the Convective Zone
I will present
evidence that
suggests that
a Two-Layer
Model of the
Sun may be
more useful
for us in
understanding
how stars
operate.
Standard Solar Model


Standard Solar Model (references)
Reactions (description, from [ref]).

Predicted spectrum (postscript file, 21K)

Predicted fluxes, from Bahcall and Pinsonneault.
The page reproduced to
the left is just for
cosmetics. You do not
need to read it. It is a
visual reminder that if an
astronomer understands
the reactions that go on
within the Sun and the
pressure and temperature
conditions that control
those reactions, they can
calculate the properties of
the interior of the Sun
with great precision even
though they have never
“seen” into the solar
interior directly.
The Sun’s internal structure is displayed in the following
four slides that show how the luminosity, mass,
temperature, and density vary with the distance from the
Sun’s center. These internal structure (L, M, T and ρ)
parameters are from the Standard Solar Model. A solar
radius (the distance from the Sun’s center to the
photosphere) equals 696,000 km.
Solar Interior Structure
Cumulative
Luminosity
Energy production is the
basis of the Two-Layer model
1
of
the
Sun.
One
layer
– the
95%
This
The
How
region
graph
big
is the
displays
shaded
core?
inthe
red
coreproduces
energyas
and
by
cumulative
represents
that
luminosity
portion
ofathe
Since
it is about
1/5’th
the
its
thermal
supports
0.75
function
Sun
located
of pressure
solar
within
radius.
0.2
solar
solar
radius, the
volume
of the
the
envelope
against
further
CORE
ENVELOPE
Notice
radii
orhow
1/5’th
the
the
luminosity
solar
radius.
core
is 1/5’th
cubed
the
collapse.
Without
the
core the
climbs toward
1 Solar
Notice
volume
that
ofwould
the
about
Sun
95%
or, of the
0.5
envelope
collapse.
The
Luminosity
as the
fractional
We will call the volume of the
entire
equivalently
Sunsolar
beyond
less
than
solar
1%
is the
second
layerluminosity
is0.2
the
envelope
radius increases.
radii the envelope. The envelope
generated
volume
produces
of the
within
Sun.
0.2
energy
Let
solar
me
that produces
nono
energy
but
0.25 (almost) and occupies 99% emphasize
radii
ofrequired
the
ofSun’s
the center.
this
volume.
result. Isn’t
The
is
to
maintain
core
this interesting? 99% of thecore
Sun’s
ofconditions.
the
volume
Sun has
that produces
fusion
We shall
call this region the
nothing to do with energy production
almost all the
– orenergy
does it? In
0
core.
Almost
all
the energy
Lets
fact, the envelope is essential
occupies
forexamine
energy
onlysome
production
1% ofother
the Sun’s
0
0.1
0.2
0.3
0.4 produced
0.5
0.6
0.7
0.8
0.9
1
by
the
Sun
occurs
properties
of the
core
and
because its weight on the core
volume.
maintains
What
the
does
core
the
other
in
the core.
envelope.
pressures so that fusion can
99%
continue.
Without
do? the
R/RSunof the Sun
envelope that core would explode!
Solar Interior Structure
1
Cumulative Mass
0.75
0.5
33%
0.25
0
0
Let’s think
About
33% 1/3
or
about this.
1/3
of
the
of the
Sun’s
How
much
of
Sun’s
mass
is
mass
is mass
the
Sun’s
the core.into
squeezed
isin
contained
2/3’rds
of the
1% ofthe
the
within
Sun’s
Sun’s mass
volume.
core?
are
the must
Thein
core
envelope.
be very dense!
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9
R/RSun
1
Density, g/cm3
Halfway
What
Imagine
Thus,isthe
athrough
that
How
characteristic
core
you
about
ofthe
had
thethe
envelope
Sun
andensity
envelope?
iron
How
is extremely
bar
the
about
ofthe
the
density
100
size
core?
high
of
is
Solar Interior3Structure
3! and
down
a loaf
in density
toofabout
ordinary
while
1 gm/cm
white
the envelope
g/cm
bread
or equivalent
Remember
is low
justto
in
like
the
white
you density.
could
of water!
squeeze
that ironthat
hasiron
a
1000 bread density
bar
density
theofsize
about
of a8
100down to a ball of about
3. So
tennis
ball,
just
like
you
g/cm
could
dothe
to white
core of
10
bread.1 That squished iron
thebar
Sun
would
is over
still10
not
100 g/cm
be
as dense as the core
timesofas
the
dense
Sun. as
0.1
1 g/cm
Pressures
are
so
great
in
the
cores
iron.
of
stars
0.01
CORE we thinkENVELOPE
that
material
of
as
sturdy
can
be
0.001
squished like white bread!
3
3
0.0001
0
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9
R/RSun
1
Solar Interior Structure
15 Million K
100,000,000
3 Million K
Temperature, K
10,000,000
1,000,000
CORE
ENVELOPE
100,000
10,000
1,000
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
R/Rhot
Sun (10’s Million K)
conclude that the core is very
We
What
What
The
How
isthe
aSun
isHow
characteristic
aenvelope
about
characteristic
is about
cool
a bit
only
a over
few
temperature
attemperature
Million
10
itscooler
very
Million
Kelvins.
outer
in Kelvins.
in
thesurface.
the
Envelope?
core?
while
is
much
(Millions
of K).
Just
This
However,
as
balanced
thethe
this
Weight
will be
Currently
Sun,
maintained
balance
Lifter
willWeight
must
eventually
like
Lifter,
Let’sour
compare
the
throughout
eventually
tire,
so
give
Sun
the Main
way,
will a
is
“happy”
because
Sun
to athe
Weight
Sequence
as
eventually
it must
with
run
lifetime
out
our of
balance
exists
Lifter.
The
Weights
the
Weight
fuel
Sun.
to sustain
Lifter,
core
the
between
the
represent
the as
Sun
hydrogen
runs out
burning.
of Sun
downward
weight
of
envelope
of
the
energy
Then
the
indown
inevitable
its core.
the
“envelope”
and
pushing
on
the
will
happen.
the
force from
coreupward
represented
by
the “core”.
Weight Lifter.
Envelope
Core
The
Gravity
Sun,
details
never
just
of like
gets
what
our
tired!
We will
explore
next
Weight
Sooner
happens
or
tolater
stars
will
allas
be
stars
how theLifter,
crushing
of
a
crushed
meet
their
the
by
same
are
the crushed
weight
fate – to
star’scores
core
can
cause
of
be
is
the
crushed
envelope.
by
intotheir
Units
thedescribed
envelope
swell64
envelopes.
&
66.
creating
a Giant star.
The Sun can be functionally divided
into two layers.
• The core
– Produces almost all the
energy
– Supports the weight of the
envelope preventing further
collapse
– Contains 1/3 the mass of
the Sun
– Has a density of near 100
g/cm3
– Has temperatures is
excess of 10 million K
• The Envelope
– Produces essentially no
energy
– Restrains the core against
blowing up and maintains
conditions for fusion
– Contains 2/3’rds the solar
mass
– Has a density of around 1
g/cm3
– Has a temperature in the
millions of K
Please keep this Two-layer Model in mind as you
study the life cycle of stars.