Download Stars!!!!

Stars!!!!
Galaxies and the Universe too!
Stars are far away!
• The closest star to Earth is the
sun.
• The next closest is Proxima
Centauri
• If you can travel at the speed of
light it would take about 8 minutes
to get to the sun and 4.2 years to
get to Proxima Centauri.
What is a Light Year?
• The distance light travels in one year. 9.5
trillion KM (This is a unit of distance, not
time)
• Light speed is 300,000 km/s
What is a Solar System?
• A star and the planets that
revolve around it
What is a Galaxy?
• A cluster of stars
• There are four different
types
Elliptical Galaxy
Spiral Galaxy
Irregular Galaxy
Lenticular
What is the Universe?
• Space and
everything in it.
• Made up of
billions of
Galaxies.
• The galaxies are
far apart so most
of the universe is
empty space.
What is Parallax?
• The apparent change in position of an
object when you look at it from different
places.
• Astronomers use parallax to measure
distances of nearby stars. They measure
how much the star moves in the sky over a
six month period
Classifying Stars!
• Astronomers classify stars by their
size, temperature, and brightness.
• Size= Small, medium, and giant
• Color and Temperature=
–Red= about 3,200 degrees Celsius
–Yellow= about 5,500 degrees
Celsius
–Blue= over 10,000 degrees Celsius
Brightness
• Apparent
Magnitude- A stars
brightness as seen
from Earth
• Absolute
Magnitude- A stars
brightness if it was
a standard
distance from
Earth
Hertzsprung- Russell Diagram
• Diagram that classifies stars by their
brightness and temperature
• Most stars are Main Sequence Stars. This
is a diagonal band on the diagram that
shows surface temperature increasing as
brightness increases
Hertzsprung- Russell Diagram
The Birth of a Star
• Stars start out a
Nebula( large amount
of gas and dust).
Gravity then pulls the
Nebula together
creating a protostar. A
star is actually born
when the gases
contract so much
Nuclear fusion starts
Formation of the Solar System
Life of Stars
•
•
•
•
A stars life depends on its mass
Small stars live for about 200 billion years
Medium stars live for about 10 billion years
Large stars live for about 10 million years
Star Deaths
When a Star Runs Out of Fuel
• White Dwarfs
• Neutron Stars
• Black Holes
White Dwarfs
– Created from small and medium stars
– When they run out of fuel the expand to a red
giant
– These gases eventually blow away leaving
the blue white core
– They are about the size of Earth but with the
mass of the sun
– When it dies it is called a black dwarf
Neutron Stars
• Super Nova is when a giant or super giant
star explodes
• What is left over is called a neutron star
– Smaller and denser than white dwarfs
– They can have the same mass as the sun but
can be the size of an asteroid
Black Holes
• This only happens to the most massive
stars.
• They become supernovas with more then
5 times the mass of the sun left.
• The gravity is so strong that it pulls all the
gases in so close that not even light can
escape
Quasars
• Quasi- stellar objects
• They are the most luminous, powerful, and
energetic objects known of at this time.
They seem to inhabit the centers of active
young galaxies and can emit up to a
thousand times the energy output of our
entire galaxy
Star Systems
• More then half of all
stars are members of
groups of two or more
stars, called star
systems
• Binary Stars- two
stars
• Eclipsing Binary- a
star system in which
one star blocks the
light from another
History of the Universe
• Big Bang Theory: The universe formed in an
enormous explosion about 10-15 billion years
ago.
• All of the galaxies are moving away from a
central point (Edwin Hubble discovered this)