Download Unit 3 - Lesson 8.9 Life of Stars Challenge

Grade 9 Academic Science – Space
Life Stages of a Star
A star has many descriptive possibilities:
 A luminous globe of gas producing its own heat and light by nuclear reactions (nuclear fusion).
 Stars consist mostly of hydrogen and helium gas.
 Surface temperatures range from 2,000OC to above 100,000OC, and the corresponding colours
from red to blue-white.
 The brightest stars have masses 100 times that of the Sun and emit as much light as millions of
Suns. The faintest and smallest mass stars have less than one-thousandth the brightness of the
Sun and about 8% of the Sun’s mass (about mass Jupiter).
 Most stars live for less than a million years.
 At the end of its life, a star swells, loses it outer layers, and then, shrinks
Some of the life stages of a star, in somewhat chronological order…
 Nebula
 Protostar
 Main Sequence Star
 Red Giant
 Red Dwarf
 White Dwarf
 Supernova
 Neutron Star
 Pulsar
 Black Hole
Task

Read the description and assign the Star Life Stage from the list above
Star Life
Stage
Description
These coloured Super Giants have luminosities often 1,000,000X greater
than the Sun
The explosive death of a star
A cloud of hydrogen gas and dust in space.
When the gravitational and pressure forces within the initial cloud become
unbalanced, the cloud collapses and breaks into small fragments. The
smallest of these fragments contract further to form these pre-stars
This catastrophic event is thought to be main source of elements heavier
than hydrogen and helium
A mass similar to that of the Sun, but only 1% of the Sun's diameter
(approximately the diameter of the Earth).
These form from massive stars at the end of their life times
Star type consists of degenerate matter with a very high density due to
gravitational effects (i.e., one spoonful has a mass of several tonnes).
Birthplace of stars
An early stage in the process of star formation
A star composed mainly of neutrons
These stars are very bright because they are so large; yet, their surface
temperature is lower than that of the Sun (…about 2000-3000OC)
Four different types

Emission that glows brightly because the gas in it is energised by the
stars that have already formed within its borders

Reflection where starlight reflects on the grains of dust

Dark that are dense clouds of molecular hydrogen which partially or
completely absorb the light from stars behind them

Planetary are the outer layers of a star that are lost when the star
changes from a red giant to a white dwarf
Typically, these stars have a mass 3X greater than the Sun but a diameter of
only 20 km. If its mass is any greater, its gravity will be so strong that the star
will shrink further and implode to become a Black Hole.
The gravitational pull is so great that nothing can escape from it, not even
light
Cool, small, faint and coloured star
A very small, hot star
Lasting about 100,000 years, it starts with a core of increased density within
a molecular cloud and ends with the formation of a star leading to the
development of a Main Sequence Star
A large bright star with a cool surface
Type of star that cools and fades
There are two types:

Type I occurs in binary star systems in which gas from one star falls
on to a white dwarf causing the dwarf to explode.

Type II occurs in stars ten times or more as massive as the Sun.
Runaway internal nuclear reactions near the end of the star life leads
to an explosion
The shrunken remains of normal stars
A large mass that forms by contraction out of the gas of a giant molecular
cloud
These large stars have diameters between 10X and 100X that of the Sun. If
the star is a Super Giant, their diameters can be up to 1000X of the Sun.
A late-life stage sub-species star that emits a beam of electromagnetic
radiation that can be only seen when the beam of emission is pointing toward
the Earth. This makes the star seems to “beat”
They distort the space around them and can suck neighbouring matter into
them, including nearby stars.
The surface temperature is about 8000OC; yet being smaller than the Sun,
the overall luminosity's is less than 1% of the Sun.
Clouds initially balanced between gravitational forces (…which work to
collapse the cloud) and pressure forces (…primarily from the gas which work
to keep the cloud from collapsing)
The Sun
A teaspoonful of their matter from this star would weigh as much on Earth as
an elephant…about 5.5 metric tons.
This star type is produced when a Supernova explodes and forces the
protons and electrons to combine
The outcomes of the explosive event is either a Neutron Star or a Black Hole
Its density cannot be measured
Stars exist in hydrostatic equilibrium (i.e., outward forces of energy
production equal impact of inward gravitational pull)
Just prior to this “life-ending” event, the star obtains a brightness of 100
million suns
It forms from a Main Sequence Star that runs out of hydrogen fuel in its core,
starts to collapse, burns hotter to create greater outward pressures and
quickly expands outward.
About 1/10 the mass and diameter of the Sun
A sub-species of star that is very dense and spinning rapidly
These star use hydrogen as their fuel source for nuclear fusion reactions
These small colourful stars burn so slowly that their estimated lifetimes are
100 billion years
Crushed by high density of gravity, the core temperature of this small star
exceeds 100,000OC
Almost 90% of all stars in the Universe
There are other life stages of a star including (1) Black Dwarf and (2) Brown Dwarf. A Black Dwarf forms
from a cooling White Dwarf; whereas, a Brown Dwarf is considered a sub-species of star. Can you
define these two star types based on information in the tables?
ANSWERS
Star Life
Stage
Description
Red Giant
These coloured Super Giants have luminosities often 1,000,000X greater
than the Sun
Supernova
The explosive death of a star
Nebula
A cloud of hydrogen gas and dust in space.
Protostar
When the gravitational and pressure forces within the initial cloud become
unbalanced, the cloud collapses and breaks into small fragments. The
smallest of these fragments contract further to form these pre-stars
Supernova
This catastrophic event is thought to be main source of elements heavier
than hydrogen and helium
White Dwarf
A mass similar to that of the Sun, but only 1% of the Sun's diameter
(approximately the diameter of the Earth).
Black Holes
These form from massive stars at the end of their life times
White Dwarf
Star type consists of degenerate matter with a very high density due to
gravitational effects (i.e., one spoonful has a mass of several tonnes).
Nebula
Birthplace of stars
Protostar
An early stage in the process of star formation
Neutron Star
A star composed mainly of neutrons
Red Giant
These stars are very bright because they are so large; yet, their surface
temperature is lower than that of the Sun (…about 2000-3000OC)
Nebula
Four different types

Emission that glows brightly because the gas in it is energised by the
stars that have already formed within its borders

Reflection where starlight reflects on the grains of dust

Dark that are dense clouds of molecular hydrogen which partially or
completely absorb the light from stars behind them

Planetary are the outer layers of a star that are lost when the star
changes from a red giant to a white dwarf
Neutron Star
Typically, these stars have a mass 3X greater than the Sun but a diameter of
only 20 km. If its mass is any greater, its gravity will be so strong that the star
will shrink further and implode to become a Black Hole.
Black Hole
The gravitational pull is so great that nothing can escape from it, not even
light
Red Dwarf
Cool, small, faint and coloured star
White Dwarf
A very small, hot star
Protostar
Lasting about 100,000 years, it starts with a core of increased density within
a molecular cloud and ends with the formation of a star leading to the
development of a Main Sequence Star
Red Giant
A large bright star with a cool surface
White Dwarf
Type of star that cools and fades
Supernova
There are two types:

Type I occurs in binary star systems in which gas from one star falls
on to a white dwarf causing the dwarf to explode.

Type II occurs in stars ten times or more as massive as the Sun.
Runaway internal nuclear reactions near the end of the star life leads
to an explosion
White Dwarf
The shrunken remains of normal stars
Protostar
A large mass that forms by contraction out of the gas of a giant molecular
cloud
Red Giant
These large stars have diameters between 10X and 100X that of the Sun. If
the star is a Super Giant, their diameters can be up to 1000X of the Sun.
Pulsar
A late-life stage sub-species star that emits a beam of electromagnetic
radiation that can be only seen when the beam of emission is pointing toward
the Earth. This makes the star seems to “beat”
Black Hole
They distort the space around them and can suck neighbouring matter into
them, including nearby stars.
White Dwarf
The surface temperature is about 8000OC; yet being smaller than the Sun,
the overall luminosity's is less than 1% of the Sun.
Nebula
Clouds initially balanced between gravitational forces (…which work to
collapse the cloud) and pressure forces (…primarily from the gas which work
to keep the cloud from collapsing)
Main
Sequence
The Sun
White Dwarf
A teaspoonful of their matter from this star would weigh as much on Earth as
an elephant…about 5.5 metric tons.
Neutron Star
This star type is produced when a Supernova explodes and forces the
protons and electrons to combine
Supernova
The outcomes of the explosive event is either a Neutron Star or a Black Hole
Black Hole
Its density cannot be measured
Main
Sequence
Stars exist in hydrostatic equilibrium (i.e., outward forces of energy
production equal impact of inward gravitational pull)
Supernova
Just prior to this “life-ending” event, the star obtains a brightness of 100
million suns
Red Giant
It forms from a Main Sequence Star that runs out of hydrogen fuel in its core,
starts to collapse, burns hotter to create greater outward pressures and
quickly expands outward.
Red Dwarf
About 1/10 the mass and diameter of the Sun
Pulsar
A sub-species of star that is very dense and spinning rapidly
Main
Sequence
These star use hydrogen as their fuel source for nuclear fusion reactions
Red Dwarf
These small colourful stars burn so slowly that their estimated lifetimes are
100 billion years
White Dwarf
Crushed by high density of gravity, the core temperature of this small star
exceeds 100,000OC
Main
Sequence
Almost 90% of all stars in the Universe
There are other life stages of a star including (1) Black Dwarf and (2) Brown Dwarf. A Black Dwarf forms
from a cooling White Dwarf; whereas, a Brown Dwarf is considered a sub-species of star. Can you
define these two star types based on information in the tables?
 Black Dwarf – Star that emits no energy
 Brown Dwarf – Star that emits very little energy, small mass so hydrogen fusion does not occur
(may fuse lithium or deuterium), differ from large planet only in formation and composition