Download What We Know About Stars So Far

What We Know About
Stars So Far
There are many different
types of light
energy…………………
Some energy we can see – Visible light
Red
Orange
Yellow
Green
Blue
Indigo
Violet (purple)
There are many different
types of light
energy…………………
Some energy we cannot see –
Infrared and Ultraviolet Light
These energies differ based
on their wavelength
•Red light has a larger
wavelength than violet
•Red is less energetic than violet
•Violet has a smaller wavelength
than red light and is a more
energetic wavelength of light than
visible light.
•Ultraviolet has a shorter
wavelength and a higher
frequency
Stars release many types of
energy that are part of the
electromagnetic spectrum.
This is what makes all
stars similar (they
release energy during
nuclear fusion).
Scientists use different
energies within the
spectrum to examine
celestial objects
(objects located in outer
space).
Scientists use different energies
within the spectrum to examine
celestial objects (objects located in
outer space).
Visible light –
tells us about
the temperature
of a star.
Red = Cooler
temperature
Blue = Hotter
temperature
Scientists use different energies
within the spectrum to examine
celestial objects (objects located in
outer space).
Radio
waves –
help us to
create
images of
distant
objects that
cannot be
seen.
Scientists use different energies
within the spectrum to examine
celestial objects (objects located in
outer space).
X-ray
Radiation
– helps us
detect
supernova
explosions
and black
holes.
What We See When We
Look at the Sky
Stars can be organized into different
categories based on their apparent
brightness.
•Scientists used to use a simple
scale of brightness to classify stars.
The star’s brightness was
dependent on how close it is to the
Earth. The closer a star is to the
Earth, the brighter it would
appear.
They used a scale of 1 – 6
1 = brightest stars
6 = least bright stars
Sizes of Different Stars
Stars can be organized into different
categories based on their apparent
brightness.
•Scientists also figured out that the
color of the star told us something
about their temperature
•Red-colored stars are cooler in
temperature compared to bluecolored stars.
Stars can be organized into different
categories based on their apparent
brightness.
Scientists later came up
with a more precise
system for measuring
brightness.
Sirius A = Brightest star
in night sky is -1.4
Sun = -27
Stars can also be organized into
different categories based on their
absolute brightness.
Scientists measure the
luminosity of the star.
This is the total amount of
radiation a star emits (the
visible and invisible
wavelengths of energy).
This system is not
dependent on how far
away a star is from the
earth.
Stars can also be organized into
different categories based on their
absolute brightness.
Scientists (Hertzprung and
Russell (HR)) found that
luminosity is dependent on
the surface temperature of
the star.
When you plot stars on a
graph using this system
(comparing surface
temperature and luminosity),
you will find that the stars
fall into groups.
Stars can also be organized into
different categories based on their
absolute brightness.
We can use this
information about a
stars luminosity to
help determine
where a star is in
its life cycle.
Stars move through a set life cycle.
At the beginning of
their lives, stars are
main sequence stars
These stars begin as a
swirling cloud of
matter (H and He
mostly) that eventually
reaches temperatures
of 15 million Kelvins
and at this point fusion
begins (atoms
colliding to form
heavier elements – H
colliding to form He).
Stars move through a set life cycle.
•The red giants produce
heavier elements like
Oxygen and Nitrogen
during fusion
•The very heaviest
elements form when a
supernova explodes.
Stars move through a set life cycle.
As the stars age, they
use up their energy
and lose mass.
• Smaller, cooler stars
burn their fuel slowly
and last longer
• Massive, supergiant
stars burn their fuel
quickly and don’t last
as long.
The loss of mass in a
star creates a stellar
wind (called solar wind
in the case of our Sun).
Stars move through a set life cycle.
Eventually, some
stars lose so
much mass that
they shrink down
and become a
nebula (a shell of
what they once
were).
Stars move through a set life cycle.
In other cases, stars
will explode and
become a neutron
star or a black
hole.
When these stars
die, heavy
elements are
formed as matter
combines.
Stars move through a set life cycle.
Eventually,
the matter that
was used to
make up a star
will contract to
form new stars
and the process
of a star’s
lifecycle will
begin again.