Transcript Brichler-powerpoint

Stars, Galaxies
and the Universe
PAGE 90 -121
How do we
measure
the
distance
between
stars?
• Parallax – an apparent
shift in the position of an
object when viewed from
different locations.
• Using parallax and
trigonometry, astronomers
can find distances to stars.
• Closer stars seem to move
more than distant stars as
the earth revolves around
the sun.
What is the
universe?
All of space and everything
in it!
It’s enormous beyond
imagination!
• How do we Lights years
measure
Scientific notation
things in
the
universe?
It is a distance not a time
What are
used to measure things
light years?
that are very far apart.
The distance that light
travels in one year at
300,000,000 meters per
second ( 186,000 miles per
SECOND) – about 9.46
trillion kilometers!
What is
scientific
notation?
It uses powers of 10 to write
very large or very small
numbers in shorter form.
Each number is written as a
number between 1 and 10
and a power of 10.
Ex. – 9,460,000,000,000,000
would be written as
9.5 x 10 15
What is a
star?
• A giant ball of gas, mostly
hydrogen and helium that
are undergoing nuclear
fusion.
• Our sun is an example of a
star.
What is a
planet?
• An object that orbits a star.
• It must be large enough to
have become rounded by
it’s own gravity.
• It must be the largest
object in it’s orbit causing
all particles to gravitate
toward it.
What is a
solar
system?
• It contains a star and the
planets and other objects
that revolve around the
star.
• Our solar system contains
the sun, and all the
planets, moons, and
objects that revolve
around it.
What is a star • Unlike our solar system,
most
stars
are
not
found
system?
alone. If there are 2 stars,
it’s called a binary star
system – more than 2
stars, it’s called a star
cluster.
What is a
galaxy?
• A huge group of single
stars, star systems, star
clusters, dust and gas
bound together by gravity.
• Much larger than star
systems or solar systems.
• Spiral – like a pinwheel.
What are the • Elliptical – round or
flattened
spheres.
major types
of galaxies? • Irregular – holds no
regular shape
• Quasars – active young
galaxies with huge black
holes at the center.
What is…
Gravity?
• The force that attracts all
objects toward each other.
Mass
• The amount of matter in
an object.
Weight
• The measure of the force
of gravity on an object.
• The masses of the objects
What
and
the
distance
between
determines
them.
gravity?
• The larger the mass and
the closer they are, the
greater the gravity.
What is
inertia?
What is
Newton’s 1st
Law of
Motion?
• The tendency of an object
to resist changes in
motion.
• An object at rest will stay
at rest and an object in
motion will stay in motion
at a constant speed unless
acted on by a force.
What is
accretion?
• The process of gradually
building something up by
gathering together smaller
pieces.
• By color/temperature, size,
chemical composition and
How are stars
brightness.
classified?
• Temperature – Hottest is
blue, coolest red.
• Blue, blue white, yellowwhite, yellow, orange, red.
• Size – giant or super giantneutron
• A device that breaks light
What is a
into
colors.
Astronomers
spectrograph
use it to determine the
?
elements found in stars.
Brightness
• Brightness depends on size
and temperature.
• Apparent brightness – the
brightness of the star as
seen from earth.
• Absolute brightness – the
brightness the star would
have if it were a standard
• A tool that astromomers
use to break a star’s light
What is a
spectograph? down into a spectrum.
• From this spectrum, we
can tell many things about
the star
• Composition
• Temperature
• A spectograph allows you
to see the emission lines.
Are there
different
types of
spectrums?
• Absorption spectrum – The
spectrum of a star. Because
a star’s atmosphere absorbs
colors of light instead of
emitting them – there are
black lines.
Continuous spectrum – A
spectrum that shows all the
colors.
What so you
call the
black lines
present in
an
absorption
spectrum?
• Emission Lines – lines
made when certain
wavelengths of light , or
colors, are given off by hot
gases
• Each element has it’s own
set of emission lines – We
call this the elements
“fingerprint”
• (see page 112)
•
It
is
really
the
HertzsprungWhat’s an H-R
Russell diagram, and it is
Diagram?
used to show the
relationship between the
surface temperature and
the absolute brightness of
stars.
• (see page 114)
What is the
Main
Sequence?
• It’s a diagonal area on the
H-R diagram that includes
more than 90% of all stars.
• These stars are in the
middle of their lives.
• Our sun is a main
sequence star.
How does a
star form?
• Nebula – a huge cloud of
gas and dust spread out
over an enormous area.
• A nebula with enough
mass to become a star is
called a protostar.
• As accretion takes place
and the atoms are
squeezed together nuclear
fusion takes place – a star
is born!
How long
does a star
live?
• This depends on the mass
of the star – the larger the
star, the shorter the life
span.
• Stars need a continuous
source of hydrogen to
continue to burn. Once
the hydrogen supply is
used up the star will die.
Smaller stars need less,
therefore live longer.
• When a star runs out of
fuel – it either becomes a
What
white dwarf, a neutron
happens
star, or a supernova.
when a star • Small to medium sized
dies?
stars like our sun will burn
out leaving only the bluewhite core called a white
dwarf. When the white
dwarf stops glowing it will
become a black dwarf.
What
happens
when a
high-mass
star dies?
When it begins to die, it
expands into a supergiant.
When the supergiant runs
out of fuel, it explodes!
This explosion is called a
supernova.
Some of the material may
become neutron stars –
even smaller and denser
than white dwarfs – only
the size of a city!! lol
What is a
pulsar?
What is a
black hole?
–A spinning neutron
star
–When the most
massive stars die, they
become black holes –
an object with gravity
so strong that not
even light can escape.
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