Transcript Life Cycle of a Star - Colina Middle School

Amazing Astronomy Fact
Light from the sun takes 8 minutes to reach you, thus you see the
sun as it was 8 minutes ago. It might have blown up 4 minutes ago
and you wouldn't know about it!
How to Measure DISTANCES in
Space
• A LIGHT YEAR is
the distance light
travels in one year
• Example: This galaxy
NCG 1300 is 70 million
light years away
• That means the light from
this galaxy travels 70
million years to reach our
eyes.
• Does NCG 1300 look like
this today?
How to Measure DISTANCES in
Space
• ASTRONOMICAL
UNIT
• The distance from Earth
to the Sun or 93 million
miles
• Used to measure
distances inside the solar
system and to nearby
stars
Astronomical Unit  A distance!
• The universe is so
ginormous (gigantic +
enormous) that scientists
came up with a really big
unit to measure it
• Astronomical Unit ~ AU
• One AU = 150 million
kilometers= 93 million
miles
• On average the earth is one
AU from the sun
How to Measure DISTANCES in
Space
• PARSEC
• The distance between
our sun and the
nearest star
• The method of parallax
gives rise to a natural
distance unit that
astronomers call the
parsec
Speed of Light
• Light is the fastest thing we
know
• It travels 300,000
kilometers per second
…that’s 186,000 miles
per second
…that’s 5.9 trillion miles per year
or one light year
…that’s darn fast
• The speed of light is a constant
Speed of Light  A Constant but
only in the near vacuum of space!
It actually changes speed as it
moves through materials of
different densities
The
BIG IDEA!
• The BIG Deal:
Astronomers can
determine the composition
and structure of the
universe by studying the
electromagnetic energy the
universe gives off
• Examples:
• Black holes emit X-rays
• Stars emit an emmision
spectra-colored bands of
light that tell us what the
star is made of.
Electromagnetic Radiation
A collection of different energies
All these energies travel in waves at the same speed…
the speed of light
Are all the energy waves the same size?
Very Long Waves
Very Short Waves
Stars and galaxies that are moving towards us are
BLUE shifted
If they are moving away from us they are
RED shifted.
Most stars and galaxies are RED shifted
indicating the Universe is EXPANDING at nearly
the speed of light!
Galaxies
• All galaxies contain
billions of stars and
are classified into four
basic shapes
• Spiral
• Barred Spiral
• Elliptical
• Irregular
Photographed
by the Hubble
telescope on
April 21, 2009
this picture
appears to be
several
galaxies
colliding
together
• THE HUBBLE DEEP Picture - a picture of the
farthest galaxies known. This image shows the
number of galaxies found in the darkest patch
of sky as seen from Earth. It is the size of a
period at the end of a sentence held at arms
length!
• There are 1500 galaxies in this picture!!
Galaxies
• Spiral Galaxies – are flat,
have a concentrated
center and pinwheel
arms that spiral out
• Gravity pulls matter to
the center making it
more concentrated
• As the galaxy spins
centripetal force makes
the galaxy flatten
What our Galaxy would look like
from space
What is the name of our Galaxy?
THE MILKY WAY
What is the shape of our Galaxy?
IT IS A SPIRAL GALAXY
Our “Milky Way” galaxy from Earth as seen
without any light pollution
This photo shows the tremendous gravitational pull and
centripetal force on this gigantic galaxy containing 100’s of
billions of stars.
Galaxies
• Barred Spiral Galaxies –
also have pinwheel arms,
spin, and have a
concentrated center and
contain billions of stars
• The arrow shows the bar
• They are different from
spiral galaxies because
their arms extend out
straight then curve
Galaxies
• Elliptical Galaxies –
contain billions of
stars and have an
elongated oval shape
What shape is this galaxy?
Galaxies
• Irregular Galaxies –
contain billions of
stars and have no
particular shape
The galaxy, called NGC 1569, sparkles with the light from millions of
newly formed young stars. NGC 1569 is pumping out stars at a 100
times faster rate than the Milky Way. This frenzied pace has been
almost continuous for the past 100 million years.
Sombrero Galaxy ~ Scientists believe it is a spiral galaxy and have
evidence there is a supermassive black hole in the center. The dust ring
around the galaxy gives it the appearance on a sombrero. This light is
28 million years old.
Galactic Cannibalism
Larger galaxies have been known to pull in matter from
smaller galaxies near by.
In 2.5 billion years the Galaxy of Andromeda will
collide with the Milky Way destroying both
galaxies and creating a new larger galaxy.
Amazing Astronomy Fact
If you could travel at the speed of light (186,000 miles
per second) it would take 100,000 years to cross our
galaxy!
Review
• Galaxies contain billions
of stars
• Galaxies are classified
into four basic shapes
• Distances between stars
and planets are measured
in AU’s and light years
• A light year is a distance
• Electromagnetic
Radiation ~ energy can
travel through space as
waves
Other Heavenly
Bodies
Nebulas
• A nebula is a large cloud
of gas and dust in space,
spread out in an immense
volume
• All stars begin their lives
as nebulas
• A nebula is relatively
short-lived, lasting a few
tens of thousands of
years, compared to a
typical stellar lifetime of
several billion years.
Butterfly Nebula
Red Spider Nebula
Cat’s
Eye
Nebula
Horsehead Nebula
Other Heavenly Bodies
Globular Clusters
• A large, round, densely-packed
grouping of older stars
• Smaller than a galaxy, most
contain less than a million
stars
• Stars in globular clusters are
all about the same age and the
same distance from Earth
Other Heavenly Bodies
Open Clusters
• Open clusters have a
loose, disorganized
appearance
• Contain no more than
a few thousand stars
• They often contain
bright supergiant stars
The
Pleiades
The Subaru’s
logo is
patterned
after this
open cluster
Amazing Astronomy Fact
When you look at the Andromeda galaxy (which is 2.3
million light years away), the light you are seeing took
2.3 million years to reach you. Thus you are seeing the
galaxy as it was 2.3 million years ago.
Review
• Nebulas are the beginning of a
star
• Globular clusters contain less
than a million stars
• Open clusters contain a few
thousand stars
• Asteroids are found in the
asteroid belt between Mars
and Jupiter
• Comets are made from ice and
rocks. Scientists believe they
contain exact matter from the
beginning of the solar system.
Life Cycle of a Star
Nebulas
• A star is born!
• All stars begin their lives
as nebulas
• In the densest part of the
nebula, gravity pulls gas
and dust together and
this starts to heat up.
• It is now called a
“protostar”
Life Cycle of a Star
Stars
• A star will become a
small, medium, or large
star depending on how
much mass is in the
protostar
• Small stars last longer
and large stars burn out
faster
• Our sun is a medium size
star and is middle aged at
4.6 billion years old
Life Cycle of a Star
H-R Diagram
• The HR diagram has stars on it at every phase in
the life cycle. It is like taking a family picture.
• There will be new babies, teenagers, parents, and
grandparents. Stars live the majority of their
lives in the main sequence (adult) phase
• Today, a star could be residing on the main
sequence (adult), but when the star ages by
hundreds of millions of years, it begins to run
out of fuel. The next "family portrait" may have
that exact same star off the main sequence as a
red giant (grandparent phase).
Life Cycle of a Star
Death of a Star
• Low to medium mass stars
expand and become Red
Giants then a small White
Dwarf which is the core of the
star
• High mass stars expand and
become Supergiants, explodes
into a supernova, and cooling
into a neutron star or black
hole.
• This Hubble photo is of a star
just after a stellar explosion
when it is “dusting off”.
Life Cycle of a Star
Black Holes
• Black holes are places where
ordinary gravity has become so
extreme that it overwhelms all
other forces in the Universe.
Once inside, nothing can
escape a black hole's gravity —
not even light.
•
Scientists believe there are
millions of black holes in the
Milky Way. However, the
nearest black hole is many
lightyears away, so we don't
have to worry about threats to
the Earth.
Life Cycle of a Star
Black Holes
March 13, 2007
• These aren't Christmas lights;
they're supermassive black
holes churning away at the
centers of distant galaxies.
• This image, taken by a many
space- and Earth-based
telescopes, is the largest
sample ever of the mysterious,
light-swallowing giants, which
are hundreds of millions of
times more massive than the
sun.
Hot Topic!!
The only thing that gives off light in the
universe is…….STARS
Amazing Astronomy Fact
If a piece of the sun the size of a pinhead were to be
placed on Earth, you could not safely stand within 90
miles of it!
Life Cycle of a Star
Nuclear Fusion
• The main sequence of a
star begins when the star
produces fuel
• Two hydrogen atoms
collide to form one
helium atom
• This collision gives off an
enormous amount of
energy and is released as
electromagnetic radiation