Stars and Constellations Golden Rule STEM Club

The Stellar Nursery, the Beginning of a Star’s Life

Stars form inside a ‘nebula’. A nebula is made up of dust, hydrogen, helium, and other gases. There are

many types of nebulae, but we will keep it general in our case. Gradually, the matter inside of a nebula

begins to contract and then undergoes a ‘gravitational collapse’ due to the forming of a center of mass.

The result is a star or all of the said matter in a VERY dense object.

Crab Nebula Pillars of Creation Carina Nebula

The Star as a Toddler, the Main Sequence

Once the star is formed, they enter the ‘main sequence’ stage. Our own Sun resides in the Main

Sequence. Here, these stars are a massive globe of gas, burning and bright by the means of nuclear

reactions. These stars can be from ~3000K - ~30,000K. (That’s 4,940.33 F- 53,540.33F!). The brightest

stars have masses 100 times that of the Sun and emit as much light as millions of Suns.

Getting Older, Red Giants and Supergiants

Next, the outer layers of the star begin to expand. This is a result of the core being hot enough to fuse

helium into carbon. The outer layers expand and the star dims. What happens next depends on the star’s

mass.

Low Mass Stars into White and Black Dwarfs, High Mass

Stars into Neutron Stars or Black Holes

Low Mass Stars

Red Giant → Planetary Nebula → White Dwarf

→ Black Dwarf

Helix Nebula (Planetary Nebula)

Low Mass Stars into White and Black Dwarfs, High Mass

Stars into Neutron Stars or Black Holes

High Mass Stars

Red Supergiant → Supernova → Neutron Star

or Black Hole

Wasn’t this the Crab

Nebula?

Supernova

This event occurs in the final stages of a star’s life. The star literally explodes causing the brightness of a

100 million suns for a short period of time. Brightness from the explosion can be tricky, it can confuse

astronomers into thinking it is just another star. A supernova is caused by the collapse of a high mass

star’s core. After Before

Neutron Stars and Black Holes

Depending on the amount mass that is pulled back, the result of a supernova could either be a neutron

star or a black hole.

Neutron stars are the smallest, but the most dense stars to exist. A small matchbox containing neutron

star material would weigh as much as 13 million tonnes!

If the gravitational pull is greater than the amount of force the star’s mass can hold, a black hole is formed.

The gravitational effects of the black hole are so strong nothing can escape it, not even light. This

phenomenon continues to baffle scientists today.

Size Comparisons of Stars (video) https://www.youtube.com/watch?v=HEheh1BH34Q

Black hole masses compared with Sun masses https://www.youtube.com/watch?v=QgNDao7m41M

Constellations

The first uses of Constellations were most likely religious. People believed that their God(s) lived in the

heavens and used the stars to communicate stories with them. Our star names and myths behind them

mostly come from Greek Mythology.

Example, the Orion Constellation. One of the many stories states: As the son of the sea-god Neptune and great

huntress Queen Euryale of the Amazons, Orion was a strong hunter with a big ego. He thought he could hunt

any animal or being. However, a single small scorpion killed Orion. To avoid any further conflict, the Scorpius

constellation is placed on the opposite hemisphere of the Orion constellation.

Constellations

● Once people began to recognize the patterns of Constellations revolving throughout the year,

constellations were used as a tool for agriculture. For example, the presence of the Orion

constellation signals the arrival of winter.

● Presently, constellations are used for navigation and pinpointing sections of the night sky for

studying by astronomers.

Orion Constellation

Not every star in the night sky is necessarily a

star. It could be a galaxy, nebula or planet. For

example, in the Orion Constellation, one of the

‘stars’ is actually a nebula and visible to the

naked eye.

Orion Nebula

Space Stuff to Think About

Our solar system revolves around one star, our Sun.

Our solar system is located in our home galaxy, the Milky

Way Galaxy.

In the Milky Way Galaxy, there is a calculation of

about 100 billion stars.

In the observable Universe, there is an estimation

of about 100 billion galaxies.

Multi-verse Theory?

Carl Sagan

American astronomer best known for his contribution to the

search for extraterrestrial life (SETI)

Assembled the first physical messages to outer space: The

Pioneer Plaque and the Voyager Golden Record.

Writer and presenter of the 1980 TV Series Cosmos

Nov 1934 - Dec 1996

Terms and Astronomers to Research

Light years v Astronomical Units

Kelvin and Celsius, conversions to

fahrenheit

Einstein’s Theory of General Relativity

Quasars

Binary Star Systems

Hubble Telescope

Carl Sagan

Neil deGrasse Tyson

Galileo Galilei

Isaac Newton