The Life Cycle of Stars                             

Purpose:

1) In this webquest, you will investigate the process of nuclear fusion explained by Einstein's famous  equation E = MC²  and learn how mass in the form of hydrogen atoms is converted to helium and causes a release of energy that makes stars shine.

We will also begin to understand the forces involved in stars that maintain this nuclear reaction and how these forces change as the star ages.

2) We will explore the stages stars progress through from birth to death and how the death of a star depends on its initial mass.

3) We will interpret Hertzsprung Russell diagrams and learn how they can be used to classify the life cycle stage of a star by its luminosity, temperature, magnitude, and spectral class.

4) Finally, we will discover how infrared, x-ray, and gamma ray telescopes are being used to detect the life cycle stages of stars.

Task #1: 
1) You will begin your webquest by learning how to identify stars by their magnitude, color, and temperature, and spectral class. 
Click Stars: Lights in The Sky and write out the answers to the following questions on a sheet of white construction paper to be turned in.
2) - Name the brightest star in the known universe. _____________________________
3) - What is its magnitude?  ___________________________________________________
4) - Are the brightest stars low magnitude or high?  ____________________________
5) - How much does the brightness of a star change with each change in magnitude of one?  _____________________________________________________________________
Do a search on the internet for "brightest stars" and make a top 10 list on your blank paper of the names of the 10 brightest stars in the known universe and their magnitude. 

6) - Finally, design a colored diagram on your blank paper that displays the colors of the hottest stars on the left to the coolest stars on the right.  Stars are grouped into spectral classes based on a range of temperatures they fall into.
*Label the spectral classes (O, B, A, F, G, K, M) appropriately under each star color in your diagram. 

Answer the following few more questions and write on your paper.
7) - What color is the brightest star?  _________________________________________
8) - What color is the coolest star?  ___________________________________________
9) -What color is our sun?  ____________________________________________________
10) -What spectral class of stars is the hottest?  _______________________________
11) -What spectral class of stars is the coolest?  _______________________________
12) - What spectral class is our sun? ___________________________________________

Task #2:  Continue to read on to the section: A Nuclear Furnace on the same webpage. The animation there shows how stars fuse the deuterium and tritium forms of hydrogen to form helium.  Your task is to design a 3-D model of this nuclear reaction. You might want to locate some colored styrofoam balls at an art supply store or utilize some type of spherical object to represent the different atoms in the reaction. Glue these on a piece of cardboard and label the names of the atoms and draw arrows showing the progression of the reaction. 

Task #3: Goto The Life and Death of Stars.  Read the short section on "Where are stars born" and see pictures of the protostars of M16: The Eagle Nebula and other nebulae (stars in formation) on this page.  Continue by reading up on Main Sequence Stars and find out how our sun compares in mass to other stars like Sirius, and Proxima Centauri. Based on its mass, will our sun be around for a while? Approximately how long before our sun consumes the inner planets of our solar system?  ________________________________________________________________

Realize that once our Sun starts to run out of hydrogen fuel and has exhausted its ability to fuse other elements like carbon and oxygen, it will become a red giant and expand in size to envelope the Earth. And surprisingly, the larger the mass of the star, the quicker it burns its fuel sources and the shorter its lifespan. Also see and read about Hubble Space Telescope pictures of a developing galactic nebula in our Milky Way Galaxy called NGC 3603

Task #4: Being that stars are quite more massive than most planet sized objects, the gravitational pull on objects close to stars is astronomically large. Find out Your Weight On Other Worlds like different types of stars and even planets.

Our Sun		Neutron Star
White Dwarf		Pluto

Which planet’s gravity is closest to the Earth’s? ________________________________

Which planet’s gravity is furthest from the Earth’s? _____________________________

Task #5: Now check out the All Star Line Up and profile one of the 34 stars on this page. Organize the info provided about your chosen or assigned star into a one page report, a small poster, or a short Powerpoint slide show.

Task #6:
The life cycle of stars continues.......All stars eventually become Red Giants or Super Giants.  As the main sequence star glows, hydrogen in its core is converted into helium by nuclear fusion. 

FYI
When the hydrogen supply in the core begins to run out, and the star is no longer generating heat by nuclear fusion, the core becomes unstable and contracts. The outer shell of the star, which is still mostly hydrogen, starts to expand. As it expands, it cools and glows red.  The star has now reached the red giant phase.

It is red because it is cooler than it was in the main sequence star stage and it is a giant because the outer shell has expanded outward.

In the core of the red giant, helium fuses into carbon.  All stars evolve the same way up to the red giant phase. 

The amount of mass a star has determines which life cycle path it will take ...........Read more about Red Giants.
 

• What makes up the “supernova remnant”?

______________________________________________________________________________

Task #7:  See animation of a Supernova explosion and photographs of actual supernova detected by emitted X-rays. At this point, stars at least 5X more massive than our Sun that have gone supernova will either die as a neutron star or a black hole. 
Make a poster display of the Life Cycle of Massive Stars on large paper or small poster board. Label and color the star types and progression correctly for full credit. 

Task #8:  Time for some fun as a reward. Play the Falling Stars Applet Game and destroy those falling stars.  Have your teacher sign off on the score you earned.   Highest score gets an extra credit reward.

Task #9: Here's a chance to model your own black hole. 
Go to Nasa's Life Cycle of Stars Curriculum packet.   Go to the activity Model a Black Hole and follow all directions there. Bring in your model to share. You may also do any of the other activities there for extra credit. See me about activities or projects you plan to do.

Task #10:  Congratulations! Now you are ready for the quiz and see how much you have mastered about the Life Cycles of Stars.