How Are the Properties of Stars Related?

Name ______Period ______How are the properties of stars related?

Essential Questions: How can we make meaning out of numbers?

Task: You are a member of a team of scientists that is studying one of outer arms of a newly discovered spiral galaxy. Your research team has just completed data collection on the color, temperature, and luminosity of the thirty outermost stars. Your objectives are to 1) plot the star data on a graph, 2) use the graph to analyze the data and 3) describe observed relationships between the properties of the stars.

Directions: 1. Plot and label the stars on the graph using the correct colors to indicate the color of the stars 2. Label the Axes of the graph (include units) 3. Title the graph (see rubric for specific requirements) 4. Clearly communicate your answers to the analysis questions using complete sentences and scientific vocabulary 5. Complete the self-assessment rubric to check your work before you turn it in Name Temperature Luminosity Color Name Temperature Luminosity Color (K) (solar units) (K) (solar units) Alpha 5,800 1.56 yellow Papa 34,000 200,000 Blue Bravo 2,800 .0005 red Quebec 7,400 1,510 White Charlie 2,700 .00002 red Romeo 3,400 5,500 red Delta 3,200 0.006 red Sierra 4,500 115 orange Echo 10,400 23.5 Blue-white Tango 10,700 55 Blue-white Foxtrot 2,700 0.00006 red Uniform 5,900 5 Yellow Golf 2,800 0.0005 red Victor 11,800 46,000 Blue-white Hotel 8,000 0.001 white Water 30,000 100,000 Blue India 4,500 0.3 orange X-ray 3,200 14,000 Red Juliet 2,800 0.0004 red Yankee 14,000 219 Blue-white Kilo 2,700 0.0001 red Zulu 9,500 13.8 Blue-white Lima 3,600 0.08 orange Alpha Alpha 8,000 11.5 white Mike 6,800 7.65 Yellow-white Bravo Bravo 4,900 105 Orange November 4,200 0.14 orange Charlie Charlie 4,200 105 Orange Oscar 3,000 0.003 red Delta Delta 21,000 2,400 Blue-white

Data Analysis - Please respond with complete sentences and scientific vocabulary.

1. Identify the color classification that represents the mode of the data. Use the data as evidence to justify your answer. (2 points)

3. Identify the relationship between a star’s temperature and luminosity as directly or inversely proportional. Explain your rationale. (2 points)

4. Use data points from your graph to complete the table below. Sequence the colors and temperatures from hottest at the top to coolest at the bottom (1 point per cell) Spectral Class Color Temperature O B A F G K M

5. Which color classification had the largest temperature range? What is the range for that data subset? (2 points)

6. Which color classification had the largest luminosity range? What is the range for that data subset? (2 points)

7. Make a logical prediction to explain why there are outliers from the data trend on the graph. (2 points)

Advanced/Gifted (answer these instead of 2 and 3 above) 2. One of your teammates on the research team states that luminosity determines a star’s color, but you argue that color is determined by the star’s temperature. Use specific data from your graph as evidence to support this argument. (2 points)

3. Another of your colleagues states that the relationship between temperature and luminosity must be inversely proportional because the slope of the data is negative. Do you agree or disagree? Explain. (2 points)

0.0001

40 000 35 000 30 000 25 000 20 000 15 000 10 000 5 000 0

(C) Copyright 2014 - all rights reserved www.cpalms.org Self- Teacher CATEGORY 5 3 1 0 Assess Assessment ment Title clearly relates Title relates to the to the problem problem being A title is present at being graphed graphed (lacks the top of the graph A title is not Title (includes both clarity in one or but does not relate present. properties). It is both properties) to the problem printed at the top of and is printed at the being graphed. the graph. top of the graph. All points are plotted correctly Some points are Most points are Most points are Accuracy and are easy to see. plotted correctly, plotted incorrectly plotted correctly of Plot A ruler is used to but there are many OR extra points and are easy to see. neatly make a trend inaccuracies. were included. line. The X axis has a The X axis has a clear, neat label clear label that The X axis has a Labeling of that correctly correctly identifies The X axis is not label but the correct X axis identifies the units the unit used to labeled. unit is not included. used to measure measure temperature. temperature.

The Y axis has a The Y axis has a clear, neat label clear label that The Y axis has a Labeling of The Y axis is not that identifies the correctly identifies label but the correct Y axis labeled. units used to the units used to unit is not included. measure luminosity. measure luminosity. Scatterplot Rubric – Please use the self-assessment to check your graph before turning it in.

Graph Score ______

Total Score

Graph Score / 20

Total Score / 46

The following pages are intended for teacher use only.

1.Identify the color classification that represents the mode of the data. Use the data as evidence to justify your answer. (2 points) The mode is represented by red stars because there more red stars than any of the other colors. There are 11 red stars, 7 blue-white stars, 6 orange stars, 2 yellow stars, 2 white stars, two blue stars, and 1 white star.

2.Identify the relationship between a star’s temperature and luminosity as a causal or correlation. Explain your rationale. (2 points) The relationship between a star’s temperature and luminosity is a correlation because one does not affect the other. Each of these properties is dependent upon the star’s mass.

3.Identify the relationship between a star’s temperature and luminosity as directly or inversely proportional. Explain your rationale. (2 points) The relationship between a star’s temperature and luminosity is directly proportional because one increases as the other is increasing and/or one decreases as the other is decreasing.

4.Use data points from your graph to complete the table below. Sequence the colors and temperatures from hottest at the top to coolest at the bottom (1 point per cell)

5. Which color classification had the largest temperature range? What is the range for that data subset? (2 points) Based on the data, blue-white stars have the largest range of approximately 12,500K.

(C) Copyright 2014 - all rights reserved www.cpalms.org Spectral Class Color Temperature O Blue 30,000 – 34,000 B Blue-White 9,500 -21,000 A White 7,400-8,000 F Yellow White 6,000 – 7,400 G Yellow 4,900 – 6000 K Orange 3,500 - 4,900 M Red 2,000 - 3,500

6. Which color classification had the largest luminosity range? What is the range for that data subset? (2 points) The red stars had the largest range of approximately 10,000 solar units.

7. Make a logical prediction to explain why there are outliers from the data trend on the graph. (2 points) The stars that lie above the main set of data are larger than the others of the same color (Giants and Supergiants) and the one that falls below the main sequence is much smaller (Dwarf). Accept any other reasonable explanation.

Advanced/Gifted (answer these instead of 2 and 3 above)

2. One of your teammates on the research team states that luminosity determines a star’s color, but you argue that color is determined by the star’s temperature. Use specific data from your graph as evidence to support this argument. (2 points) Outliers show that luminosity may vary when temperature is constant, but temperature ranges will correlate with color regardless of the luminosity. For example, star Victor has a temperature is 48,000 which falls within the blue range; however, its luminosity is much higher than the other blue and blue-white stars.

3. Another of your colleagues states that the relationship between temperature and luminosity must be inversely proportional because the slope of the data is negative. Do you agree or disagree? Explain. (2 points) I disagree with my colleague. Even though the slope of the graph appears to be negative at first, the numeric values along the x axis are reversed compared to the typical format of a graph, which goes from lower values on the left to higher values on the right. Evaluating the data points on the graph, the general trend shows that luminosity increases proportionally to temperature because one increases as the other increases and/or one decreases as the other decreases. Star data used to create table

(C) Copyright 2014 - all rights reserved www.cpalms.org Name Temperature Luminosity Name Temperature Luminosity (K) (solar units) (K) (solar units) A Alpha Centauri 5,800 1.56 P UW Canis Majoris 34,000 200,000 B Barnard's Star 2,800 .0005 Q Canopus 7,400 1,510 C Wolf 359 2,700 .00002 R Antares 3,400 5,500 D Lalande 21185 3,200 0.006 S Arcturus 4,500 115 E Sirius 10,400 23.5 T Vega 10,700 55 F Proxima Centauri 2,700 0.00006 U Capella 5,900 166 G Ross 154 2,800 0.0005 V Rigel 11,800 46,000 H Procyon B 8,000 .001 W Beta Centauri 30,000 100,000 I Epsilon Eridani 4,500 0.3 X Betelgeuse 3,200 14,000 J Ross 128 2,800 0.0004 Y Achernar 14,000 219 K Luyten 789-6 2,700 0.0001 Z Fomalhaut 9,500 13.8 L 61 Cygni 3,600 0.08 AA Altair 8,000 11.5 M Procyon 6,800 7.65 BB Pollux 4,900 41.7 N Epsilon Indi 4,200 0.14 CC Aldebaran 4,200 105 O Sigma 2398 3,000 0.003 DD Spica 21,000 2,400

Star data obtained from: http://upload.wikimedia.org/wikipedia/commons/1/17/Hertzsprung-Russel_StarData.png