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Jan 23
Test Prompt
1. As a star runs out of nuclear energy, what do
you think will occur to the size of the star?
Provide an explanation as to why you think
that.
News/Updates
• Wednesday – Life and Death of a Star
– VERY IMPORTANT (we’ll review today)
• Thursday – Hubble’s Constant activity
– LESS IMPORTANT (we’ll review on today/Monday)
Today’s Date
Opening Activity Work
Today’s Note(s)
Intro
Nebula
Protostar
3 Types
Death of LM
Main
Sequence
Giants
Death of MM
Death of HM
Blackhole
Star Forces
Exit Activity
Today’s Picture(s)
Your Own
Model
Exit Slip
Star Cycle
• There are 6 primary steps in the life and death
of stars.
Nebula Cloud
• The nursery of stars. This “cloud” is a
combination of Hydrogen, gas, and dust
(remnants of other stars and objects of the
universe).
• The matter used to make stars are recycled
from other substances in the universe.
Nebula
Protostar
The beginning of a star. The nebula cloud
condenses due to gravity and forms a solid
body.
The condensing of matter releases energy, the
protostar is the first stage in which light is
emitted.
Protostar
Depending on the amount of matter in the nebula
cloud, stars will either become low, medium or high
mass stars.
ALL of the stars create Helium from fusing together two
Hydrogen nuclei.
Low Mass Stars
High Mass Stars
Med Mass Stars
Makes Helium Iron
Makes Helium Carbon
Makes Helium
only
Death of Low Mass Stars
• When running out of fuel, low mass stars will
simply collapse and die out.
Medium Mass Stars
• The main life of a medium mass stars is known as
“main sequence stars”
• There are different types of main sequence stars
depending on the size/mass/ temperature/
luminescence/ etc.
• Our sun is a “G” main sequence star (all other
stars in the universe are compared to our sun).
Medium mass stars turn into Red Giants
High mass stars turn into Super Red Giants
• When running out of fuel, medium and high
mass stars will expand into red giants and
super red giants.
High
Mass
Super Red
Giants
Fuses to make
Iron
Med
Mass
Red Giants
Fuses to make
Carbon
Death of Medium Mass Stars
• When fuel is completely gone, the medium
mass stars will shrink on their own gravity.
• Red giants will turn into dwarf stars depending
on the amount of energy left (red dwarf, white
dwarf, brown dwarf, etc.)
Red Giant
Dwarf Stars
Death of High Mass Stars
Supernovas
• Depending on the amount of
mass/energy, the stars can explode.
Super
Red
Giants
Supernova
• High Mass stars often times explode!
• This spreads all of the elements
Hydrogen through Iron (which makes
up our planets and other new stars)
and forms all elements after Iron (up
to element 92- Uranium).
Blackhole
• Blackholes are the result of dwarf
stars that collapse on themselves.
• The stars have run out of fuel (so
no light is emitted), therefore it
looks dark/black.
• But still has a lot of gravity/mass in
a little spot (about the size of a
small town)
Dwarf
Stars
Black Hole
Forces of a Star
Thermal Expansion vs Gravity
As a star fuses Hydrogen into
Helium and into other elements,
this creates a release of energy
and therefore increased
radiation pressure that is called
thermal expansion.
As the core runs out of energy,
the star begins to expand and
near the end of it’s life will
either collapse into a dwarf due
to gravity, or will supernova due
to an increase in thermal
pressure.
Exit Activity
On the back of your graphic organizer/note
handout, there is an essential question
regarding the energy of a star and the lifetime of
the star.
Create a hypothesis to the question, then look at
the data provided to pull out specific evidence,
write a justification of why you pulled that
evidence, then write a claim.