The Last Cuentista STEM Extension: Life as a Star

Red Dwarfs, Red Giants, White Dwarfs, Black Holes

The Last Cuentista STEM Extension

LIFE AS A STAR

Starstruck

In Chapter 17 of The Last
Cuentista, as Petra’s shuttle
descends to the surface of
Sagan, she remembers what
her dad told her about the
planet’s RED DWARF sun.

In this slideshow, we’ll explore
how red dwarf stars like
Sagan’s sun differ from our
own sun, and how both these
suns compare to other stars in
the universe.

Stars begin life
in clouds of
space dust and
gas called
nebulae.

Watch the video
to see what they
look like.

A Star Factory Tour

Gravity makes clumps inside these clouds of dust and gas.
When one of these clumps gets tightly compacted and squished
together, we say its density goes up.

DENSITY means how tightly something is packed together.

Dense & Dusty Origins

A Star Is Born

Eventually these
clumps get super hot and dense and begin to stick together.

Watch the video to
learn what happens
next.

It looks like this video isn't there anymore but it is!

Fusion Fever

Inside every newborn star
hydrogen atoms smash
together to make helium.

This process is called
FUSION. It creates the
energy that powers every
star for the first few
billion years of its life.

This is how a hydrogen atom looks under a very powerful microscope.

Dropdown

Stars form in clouds of

Select answer

called ​

Select answer

.

Dropdown

Stars form as clumps of ​

Select answer

​ that

Select answer

and get more ​

Select answer

, and begin to ​

Select answer

.

Multiple Select

What's fusion? Choose 2

• a star's energy

• when hydrogen atoms smash together to form helium

• a sign a star is dying

• astronaut food made of dehydrated avocado and lo mein

Meet the Red Giant

After a star like our
sun burns up all its
helium, it becomes a
RED GIANT.

Watch the video to
learn how.

Meet the Red Giant’s Cooler Little Sister, the Red Dwarf

Red dwarf stars are
much younger, smaller
and cooler than Earth’s
sun.

In fact, they’re so young
–– only 13 billion years
old –– that the universe
has not existed long
enough for any of them
to grow up to be red
giants yet, but scientists
believe they will.

The Red Dwarf Next Door

The closest neighbor star to Earth’s sun, Proxima Centauri, is a
red dwarf, just like Sagan. This star hosts at least two planets.
Scientists believe these planets –– like Sagan –– are tidally locked
to their sun. This means one side of the planet is always day and
the other side is always night.

If you hate going to bed you might like the sunny side of Sagan.
Still, even though it’s next door, it’s over 4 light years away, which
is six trillion miles, so you probably won’t be visiting any time
soon.

Related Resource
STEM Extension: Tidal Locking

STEM Extension: Binary Stars

Multiple Select

What's a red giant? Choose 2.

• a star that has stopped fusing hydrogen into helium

• a star nearing the end of its life

• a new star

• a type of rock on Sagan

Multiple Choice

Earth's sun is not a red giant yet. What would be a clue that it is?

• the sun would burn up the inner planets of the solar system, including Earth

• the sun would glow green at night and purplish-blue in the day

• new sea creatures would begin to evolve on Earth

• the sun would emit a sticky substance that kills some animals but makes others bigger

Multiple Select

What's a red dwarf? Choose 2.

• Proxima Centauri

• a young, cool star

• an insensitive way to refer to people with Petra's eye problem

• a smaller red giant

Multiple Choice

What does the real star, Proxima Centauri, have in
common with Sagan’s fictional sun?

• they are both the closest stars to Earth

• they are both red dwarfs

• they both host planets

• they are both despised by Petra's mom

Planetary Nebula

Eventually, a
red giant
burns up all of
its energy.

Watch the video to learn more about the fate of stars like these.

Star Graveyards

Some nebulae hatch baby stars.

But PLANETARY nebulae sort of do
the opposite. They are the leftovers of stars that have died.

Watch the video to see our closest
planetary nebula neighbor, the
Helix Nebula.

BTW, planetary nebulae were named by ancient astronomers who
mistakenly thought they were planets.

White Dwarfs & Black Dwarfs

After a red giant’s
atmosphere drifts off as
a PLANETARY NEBULA,
the star becomes a hot
WHITE DWARF then
eventually cools as a
BLACK DWARF.

Watch the video to learn how.

Match

Match the following

• Planetary nebulae

• white dwarfs

• black dwarfs

• red giants

dead star leftovers

dead stars that are still hot

dead star that have cooled down

stars that stop doing fusion

• dead star leftovers

• dead stars that are still hot

• dead star that have cooled down

• stars that stop doing fusion

Multiple Select

What are planetary nebulae? Choose 2.

• planets that cannot support life

• dead star leftovers

• clouds of gas and dust ancient astronomers mistakenly thought were planets

• clouds of gas and dust stars create when they engulf the planets they host

Reorder

Put the star stages below in order of first to last.

• red giant

• white dwarf

• black dwarf

• planetary nebula

1

2

3

4

• 1
• 2
• 3
• 4

Supernova

Not all stars become
white and black
dwarfs.

Super massive stars,
many times the size
of our sun, go out
with a bang.

Meet the
SUPERNOVA!

Neutron Stars: Cosmic Zombies

After a super-massive
star collapses in a
supernova, all that
remains is its very
dense core. This object
is called a NEUTRON
STAR.

Watch the video to
learn more.

Black Holes

Some stars end their lives
with even more drama
than a suprnova.

The MOST massive stars
of all spend eternity as
BLACK HOLES.

Watch the video to learn
more.

Multiple Choice

Do all star lives end in supernovae explosions?

• yes

• no, only very massive stars

• no, only small stars

• it depends on which galaxy the star is in

Dropdown

Super-massive stars much larger than the sun end their lives

Select answer

that blast away everything except the star's ​

Select answer

​

Select answer

, which is called a ​

Select answer

.

Multiple Select

What are black holes? Choose 2.

• spots in space where gravity is so strong that nothing, including light can escape them

• the collapsed cores of the most massive dead stars

• what the Collective calls the places where they put people they purge

• A celestial body that emits large amounts of radiation

Multiple Select

Choose 3 ways a star's life could end.

• as a black dwarf

• as a neutron star

• as a black hole

• by growing new planets to host

• in a storm like the one on Jupiter