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Journal 3/2/17
Do you think nebulae help to prove that God exists?
Objective
Tonight’s Homework
To learn more details about
the final stages in the life of a
star
Finish Nebula Research by
Monday
Planetary Nebulae
Pick 2 nebulae from the list and answer the questions below:
Thor’s Helmet
Helix Nebula
Hourglass Nebula
Ghost of Jupiter
Owl Nebula
California Nebula
Dumbbell Nebula
Red Spider Nebula
Homunculus Nebula
Butterfly Nebula
Veil Nebula
Ant Nebula
Ring Nebula
Footprint Nebula
Skull Nebula
Eskimo Nebula
Camel’s Eye Nebula
Box Nebula
Bug Nebula
Retina Nebula
Blue Snowball Nebula
Cat’s Eye Nebula
Spirograph Nebula
Witch’s Broom Nebula
Medusa Nebula
Stingray Nebula
Crab Nebula
Red Rectangle Nebula
Boomerang Nebula
Flame Nebula
1) Find the “NGC” or “IC” number for the nebula. Find what NGC means.
2) How far away is your nebula? How old or big is it?
3) List 5 interesting facts about the nebula
4) Find a good picture of the nebula
5) What is the nebula made of?
Notes on Stellar Remnants
No matter the size of the star or whether it dies
quietly or in a supernova, all stars will form a
planetary nebula.
The nebula is made out of the gases that got
blown from the star. It may look like it expands
slowly, but these gases move out at an average
of 30 miles/second.
Most of this is hydrogen, but we also find
oxygen, nitrogen, sulfur, and many others. We
can identify the gases by the colors we see.
Extra Notes on Stellar Evolution
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Extra Notes on Stellar Evolution
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Notes on Stellar Remnants
When a star dies, if the core has less mass than
1.4 times the sun, it will form a white dwarf.
Gravity is trying to squeeze the core as small as
it can get. It's stopped by the pressure of
electrons trying to repel each other. This
pressure counteracts gravity.
Over billions of years, this hot core will slowly
cool down and fade to become a black dwarf.
Notes on Stellar Remnants
But what if our star is bigger than this?
We said that a star’s life is a constant battle
between pressure and gravity.
In a normal star, the
pressure from fusion
balances the pull of gravity.
When a star dies, it leaves
behind a white dwarf. In
this small object, fusion is
no longer happening, so the
core begins to collapse.
Without fusion, what stops it?
?
Notes on Stellar Remnants
Something called “electron degeneracy
pressure”.
As the atoms squeeze together, the electrons in
each atom don’t want to overlap. The
electromagnetic force pushes them apart. This
pressure holds up against gravity’s crush.
Notes on Stellar Remnants
But what if we have an even bigger core? With
enough pressure, we can FORCE atoms to let
their electrons overlap. This happens for stars
with cores up to 3 times heavier than the sun.
This is the case with neutron stars. When a big
core dies, gravity crushes down, but it crushes
even harder than electron degeneracy pressure.
As the electrons overlap, they merge with the
protons to turn into neutrons. The neutrons all
crush together, at which point their neutron
pressure is enough to stop the collapse from
gravity.
Notes on Stellar Remnants
So let’s pause here for a second. Neutron stars
are very weird because they’re essentially a
super-giant atomic nucleus.
First, a teaspoon of material from one can weigh
up to a billion tons. (A large mountain)
Second, an entire neutron star would be smaller
than the Denver metro area. (3 times the mass
of the whole sun!)
Third, if you collapse a spinning thing, it speeds
way up. Most neutron stars rotate between 3
and 30 times a second. (24 hours for Earth)
Notes on Stellar Remnants
These spinning neutron cores usually have crazy
strong magnetic fields and shoot out tons of
radiation from their poles.
As a last point, we think we may have found a
few planets orbiting some neutron stars which is
really weird. We truly have no idea what such a
planet would be like.
Notes on Stellar Remnants
Crab
Nebula
Pulsar
Notes on Black Holes
But if our core is big enough and has enough
gravity, even this neutron pressure won’t stop
things.
Gravity will push the neutrons together and we’ll
have gravity alone with no force to push
outward.
The entire core will keep squeezing down into a
single, infinitely small point. Within this point is
all the matter that was in the star’s core. Inside,
the rules of physics break down. Time and space
separate.
Exit Question
To become a neutron star, a star’s core has to be more
than _____ times heavier than the sun, but less than
______ times heavier.
1 / 10
3.2 / 9.5
2.2 / 4
7 / 9.5
1.4 / 3
No one knows