SUN, STARS AND GALAXIES

1
SUN, STARS AND GALAXIES
2
SUN, STARS AND GALAXIES
DESCRIBE THE LIFE CYCLE OF A STAR
3
SUN, STARS AND GALAXIES
Interstellar gas and dust particles inside a
nebula will start to collide and stick to each
other As the area becomes bigger, it has more
gravity so it attracts more particles and
becomes even bigger Gravitational forces cause
nebula to shrink and start spinning
4
(No Transcript)
5
SUN, STARS AND GALAXIES
Spinning nebula will flatten into a disk with
a Large mass in the center called a protostar As
particles inside center collide and pressure
in center increases, temperature in protostar
increases Hydrogen atoms start to collide and
combine together to form helium by nuclear
fusion The central core of the protostar ignites
and releases energy making a star
6
SUN, STARS AND GALAXIES
Most of a stars life is spent as a main sequence
star as it continues to fuse hydrogen into
helium The energy from fusion trying to make the
star expand is balances by the force of gravity
trying to make the star shrink so the star is
stable The death of a star begins when it has
used up almost all of the helium in its core and
the helium atoms start to fuse into carbon atoms
7
SUN, STARS AND GALAXIES
Fusing of carbon produces so much energy that
the gravity of the star cannot hold the gasses
around the core and the gas envelope starts to
expand forming a red giant star. When all of the
helium is fused into carbon, the star Releases
the rest of its gas to form a planetary Nebula
around the dying star
8
SUN, STARS AND GALAXIES
As the core of the star cools, it forms a white
dwarf star that will glow until all the heat is
released One all of the heat is gone, the star
is a black dwarf that releases no heat or
light OR As the white dwarf star cools the
pressure increases and the star explodes as a
nova
9
SUN, STARS AND GALAXIES
Large mass stars will produce red giant stars as
the fusing of hydrogen atoms in carbon produces
so much energy that the gravity of the star
cannot hold the gasses around the core The core
produces so much gravity that the gas envelope
around the star, producing enough pressure for
the carbon atoms to fuse into nitrogen and iron
10
SUN, STARS AND GALAXIES
Iron core builds up large amounts of pressure and
produces a massive explosion called a
supernova that spreads material from the core and
the gas envelope throughout Interstellar space
The remaing core material produces a fast,
spinning neutron star or a pulsar (a neutron
start that emits radiation)
11
SUN, STARS AND GALAXIES
The neutron stars of some supernova explosions
have so much mass that they produce a black
hole The neutron star in the center of a black
hole has so much gravity that even the light from
the stars around it cannot escape
12
SUN, STARS AND GALAXIES
EXPLAIN HOW A MAIN SEQUENCE STAR PRODUCES ENERGY
In the core of all main sequence stars, hydrogen
atoms chemically bond together to make
helium atoms When this happens, large amounts of
light and heat energy are released
13
(No Transcript)
14
SUN, STARS AND GALAXIES
INTERPRET AN H-R DIAGRAM
15
SUN, STARS AND GALAXIES
An H-R diagram compares the surface temperature
of stars (identified by their color) with their
absolute magnitude (how bright the stars actually
are)
16
SUN, STARS AND GALAXIES
For most stars, as the surface temperature increas
es, the brightness of the star increases The
main band of stars in the diagram are called main
sequence stars The cool bright stars in the
upper right are the red giant stars that appear
bright because they are so large Stars in the
lower left are white dwarfs that are hot but
appear dim since they are so small
17
SUN, STARS AND GALAXIES
DESCRIBE THE VARIOUS TYPES OF GALAXIES
Galaxies are grouped based on their shape
18
SUN, STARS AND GALAXIES
DESCRIBE THE STRUCTURE OF THE SUN
The sun is a typical main sequence star so the
structure of the sun is similar to the
structure of all of the stars you see in the
night sky The center of the sun is the core.
This is where hydrogen atoms are being fused
together to make helium atoms. The core of the
sun is a gas, not a solid.
19
SUN, STARS AND GALAXIES
The area of the sun that surrounds the core is
called the radiative zone. This area passes some
of the heat energy from the core to the surface
of the sun. The area around the radiative zone
is the convective zone. This layer has
convection currents where warm gases rise to the
surface, release some of the heat energy, then
cools and sinks back toward the core
20
SUN, STARS AND GALAXIES
The gases around the sun form the
suns atmosphere. The inside layer of the
atmosphere is called the Photosphere. This is
the layer that we see From Earth The middle
layer of the atmosphere is called The
chromosphere. This layer transfers The heat
energy from the photosphere to the corona.
21
SUN, STARS AND GALAXIES
The outside layer of the atmosphere is the
corona. This layer is usually only visible from
Earth during a total eclipse of the sun (when the
moon gets between the Earth and the sun)
22
SUN, STARS AND GALAXIES
EXPLAIN THE NEBULAR THEORY OF SOLAR SYSTEM
FORMATION
The solar system started out as a spinning mass
of Gas and dust called a nebula Shockwaves from
nearby supernova explosions and Other forces
caused the particles in the nebula To be pused
together and form larger particles inside The
dust cloud The bigger particles formed in the
center of the nebula And eventually got large
enough to start nuclear fusion And form the sun

23
SUN, STARS AND GALAXIES
Small groups of material formed together to Make
planetesimals (small pre-planets) Some of these
planetesimals collided with each other to form
larger masses called proto-planets. These
had Enough gravity to attract even more materials
and formed planets and their moons. When the sun
ignited into a star, it created a shockwave that
blew most of the remaining dust and other
material out from in between the planets.