stage 2 4542977 2

HR Diagram Activity  (30 points)

Brief Overview of Activity: Use an HR diagram to learn about the differences between the stars in our stellar neighborhood and the brightest stars in the sky.

Required Items: this HR diagram, red & black ink pens.
 

Procedure:

On the HR diagram, plot each star from the “Brightest Stars Group” in black ink and then plot each star from the “Nearest Stars Group” in red ink. 
Data for both groups of stars can be found below. 

Describe any differences between the two groups of stars – such as their location on the diagram, color, mass, and the types of stars in each group. 

Which of the two groups of stars is most representative of the vast majority stars in the universe?

Data

Brightest Stars Group

Name	Spectral Type	Absolute Mag
Sirius	A1	1.45
Canopus	F0	-5.63
Rigel Kentaurus	G2	4.39
Arcturus	K2	-0.32
Vega	A0	0.61
Capella	G8	-0.52
Rigel	B8	-7.01
Procyon	F5	2.66
Betelgeuse	M2	-5.48
Achernar	B3	-2.71
Hadar	B1	-4.78
Altair	A7	2.22
Aldebaran	K5	-0.63
Acrux	B0.5	-4.18
Spica	B1	-3.44
Antares	M1	-5.12
Fomalhaut	A3	1.75
Pollux	K0	1.07
Deneb	A2	-6.90
Mimosa	B0.5	-3.90

Nearest Stars Group

Name	Spectral Type	Absolute Mag
Sun	G2	4.83
Proxima Centauri	M5.5	15.48
Alpha Centauri A	G2	4.38
Alpha Centauri B	K0	5.71
Barnard’s Star	M3.5	13.25
Wolf 359	M5.5	16.64
Lalande 21185	M2	10.44
Sirius A	A1	1.44
Sirius B	A2	11.34
Epsilon Eridani	K2	6.20
Lacaille 9352	M1	9.76
Ross 128	M4	13.53
61 Cygni A	K5	7.48
61 Cygni B	K7	8.31
Procyon A	F5	2.65
Procyon B	A0	12.98
Struve 2398	M3	11.17
Groombridge 34	M1.5	10.31
Epsilon Indi	K4	6.98
Tau Ceti	G8.5	5.68

Radioactive Dating Activity (due at Stage 2) (30 points)

Brief Overview of Activity: Radioactive decay is one of the sources of the heat that drive the Earth’s geologic activity. Radioactive decay also allows us to date rocks and determine the age of the Earth and other solar system bodies.

Required Items: 36 coins, a calculator, pencil & paper.
 

Procedure:

In this activity you will simulate the radioactive decay of 36 atoms of a rare isotope of uranium, U-235. Uranium-235 has a half-life of 700 million years. Gather 36 coins and arrange them in a 6 x 6 grid with all of the coins facing heads up.

Flip each coin into the air and then place it back in its original location on the grid. This represents the passage of 1 half-life (700 million years for this example). The coins that came up heads represent atoms that have not yet decayed; the coins that came up tails represent atoms that have decayed. Record the number of heads below.

Next flip each one of the remaining heads-up coins once and place it back in its original location. 1.4 billion years have now passed by (2 x 700 million). Record the number of remaining heads below. Repeat this process until all coins are tails up.

_______ Original number of U-235 atoms

_______ Remaining number of U-235 atoms after 1st flip

_______ Remaining number of U-235 atoms after 2nd flip

Add additional lines as needed.

 

Questions:
How many half-lives did it take for all of the atoms to decay? 
How many years does that equate to? 
Do you think everyone in class will get the same answer? Why?