Transcript Stars - TeacherWeb

Main Sequence Stars
• all stars fuse hydrogen into helium
• 90% of all stars, including our Sun, are
main sequence stars
• range from high luminosity (brightness)
and high surface temperature to low
luminosity and low surface temperature
HertzsprungRussell
Diagram
Classifies stars based on
their absolute magnitude
and surface temperature.
Absolute magnitude is
how bright a star would
be if all of the stars were
the same distance from
Earth.
Surface temperature is
related to a star’s color.
Nebulae
• A nebula is a cloud of dust, hydrogen gas
and plasma.
• The material clumps together to form
larger masses that eventually are big
enough to form a protostar.
• This is the first stage in the star life cycle.
• Nebulae often create star-forming regions,
such as the Eagle Nebula.
Eagle Nebula – Pillars of Creation
Cat’s Eye Nebula
Ant Nebula
Crab Nebula
Protostar
Brown Dwarf
• have a size between that of a giant planet like
Jupiter and that of a small star
• any object 15 to 75 times the mass of Jupiter
• the object would not have been able to sustain
fusion like a regular star - called "failed stars"
• all are parts of a binary system. (two stars orbit
around one another)
• possible that brown dwarfs represent a lot of the
mass in the universe
Main Sequence Star (our sun)
Red Giant
• When a middle
aged star begins to
die, the temperature
near the core rises.
• The star expands.
• This will happen to
our sun in about 5
billion years.
• Once the red giant runs
out of energy, it collapses
and becomes a white
dwarf, a small and dense
star.
• A white dwarf is the core
of the original star. It is
very hot and cools down
over the next billion
years.
White Dwarf
- star near the
end of its life
- was a red
giant star that
lost its outer
atmosphere
White Dwarves photo taken by the Hubble Space Telescope
BPM 37093 is a huge white dwarf star
nicknamed Lucy
BPM 37093 = Lucy
• 50 light years from Earth in
the constellation Centaurus
• 2500 miles across
• weighs 2.27 thousand trillion
trillion tonnes
BPM 37093 = Lucy
•the diamond core is 50% to
90% of its mass (size of our
moon!)
• equal to 10 billion trillion
trillion carats, which is 1 with
34 zeroes (1 carat = 200 mg)
• will happen to our sun in 7
billion years.
Named Lucy after The Beatles’ hit
Lucy in the Sky with Diamonds
Black Dwarf – a white dwarf that has cooled, lost its energy
and no longer gives off light. It is a black object in space.
Giant Stars are more luminous than our sun and are
10 to 100 times larger in diameter than our sun.
Supergiant Stars are more luminous than giant stars and
more than 100 times the diameter of our sun. They are
relatively cool stars.
Betelgeuse is a supergiant star.
Supernova – collapse of the core of a red giant star produces
a shock wave that blasts the star’s outer layers into space
Remains from a supernova
Neutron Star – the core left
behind after a star’s
supernova explosion
Pulsar – a neutron star that spins very fast and
emits burst of radio waves
What if the star was SUPER
MASSIVE?
• Disclaimer: The following was put together
by Mrs. Donahue. Upon discussion, both
myself and her head began to hurt. In lieu
of our brains exploding, we decided that
we will both never fully understand what
you are about to observe.
• Here goes nothing….
• Einstein’s mathematical formulas
predicted the existence of very
dense invisible stars but he did not
believe they actually existed. He
was wrong!
• As a giant star collapses, its core
plunges inward and temperatures
reach 100 billion degrees.
• Hunks of iron bigger than Mount
Everest are compacted to the size of
grains of sand.
• Atoms are shattered into electrons,
protons, neutrons and these are
pulped into quarks, leptons, and
gluons.
• Tinier and tinier, denser and
denser…………………………
• Most massive stars become
black holes when they die.
• The dividing line between
inside and outside a black
hole is called the event
horizon.
• Quasars are galaxies with
black holes at their center.
The Milky Way Galaxy has
a black hole at its center
named Sagittarius A*.
Black Hole
Here is a picture of a black hole.
Black Hole
• To escape Earth’s gravity
you need to accelerate at
7 miles per second (12
times faster than a bullet).
We have been able to do
this with rockets since
1959.
• The gravity of a black hole
is so strong that even light
can’t escape. The speed
of light (186,282 miles per
second) is too low!
Time is affected by gravity.
• Extremely accurate clocks
placed on the lowest and
highest levels of the
Empire State Building tick
at different rates.
• Clocks on GPS satellites
have to be set to tick
slightly slower than those
on Earth’s surface to
make GPS accurate.
• One minute on the Sgr A*
event horizon is 1000
years on Earth.
• Therefore, black holes are
time machines.
What happens if you cross the
event horizon into a black hole?
a) You burn up in the fire wall.
b) Nothing. You pass through. You’re fine.
c) Then you get “spaghettified.”
a) As you fall, gravity gets stronger so the pull
on your feet is greater than the tug on your
head and you get stretched until you are
ripped apart.
b) The pieces that reach the bottom encounter
a singularity. ???????????????????????
New Thoughts
• We are in a multiverse – a collection of
universes, each of which is a separate
bubble of reality.
• The Big Bang that created our universe
was the result of a singularity “opening.”
• March 10 on the National Geographic
channel, series premiere of Cosmos: A
Space Time Odyssey.