Monday April 25 Tuesday April 26 Unit QuestionWhat do we know about the universe? How do we know it? Guiding Question / Learning Target How do astronomers study the lifecycles of stars? Warm-up Will the sun always be there? Why? What might happen to it? Agenda 1.H-R Diagram and the Lifecycle of Stars Homework Quiz Friday

Stellar Diversity Do all the stars look the same in this picture?

Arrange from oldest to youngest

Questions About the Snapshots What is the correct order chronologically by age? DCHFAEGB

Questions About the Snapshots Was this task difficult? Why or why not?

If you were an alien… What are some properties and characteristics that we could use describe people? What could you see or measure about humans to compare them? Do some of these characteristics change over time?

Could you do this for stars? Can you use the same properties? Would it be easier or harder?

Place the images in order for a star’s life

Questions About the Star: Was this task difficult? Why or why not?

Stars Live Longer! Classifying Stars Stars are far away and live billions of years Classifying People People (usually) live less than 100 years

Ways to describe humans

Direct Relationship Direct relationship or positive correlation When one property is large, the other property is large When one property is small, the other property is small

Inverse Relationship Inverse relationship or negative correlation When one property is large, the other property is small

Constant Relationship When one property changes, the other property stays the same chromosomes

No Relationship When two properties are unrelated When one property changes, the other property may or may not change

Stars are like pictures of unrelated people Astronomers must look at pictures of different stars to try to understand their life cycle

What this has to do with stars? Astronomers use the properties of stars to find out if there are any relationships between them. Brainstorm observable characteristics of stars that might help us determine age

Will relationships between these help determine age (or point in the life cycle) of a star? Will some characteristics change over time?

Variables: – Diameter: or (R ʘ ) “size” compared to the sun, where sun = 1 – Temperature : Kelvin (K) room temperature in kelvin is about 293⁰ – Mass : in units of our sun (sun = 1) – Luminosity : (brightness) in units of our sun (L ʘ ), how many times brighter / dimmer is it. – Color

ignore Numerical data here Consider this yellow.

H-R diagram explorer Quickly sketch the changes to the left star as you go through variables Be sure to write your numeric data!

In pairs One side of whiteboard: Write a claim about the relationship between radius and luminosity. Other side of whiteboard: Write a claim about the relationship between temperature and color.

Graphing other properties From a database of 90 stars, look at the graphs comparing Diameter, Temperature, Mass, and Luminosity.

As a pair Tell me the relationship Rank for strength GraphRelationshipStrength (1 most, 6 least) Mass v. Diameter Temperature v. Diameter Luminosity v. Diameter Mass v. Temperature Mass v. Luminosity Temperature v. Luminosity

As Partners Pick your top two strongest relationships to write on your whiteboard Be ready to explain why you chose these graphs

Mass v Diameter

Temperature v. Diameter ?

Luminosity v. Diameter

Mass v. Temperature

Mass v. Luminosity

Temperature v. Luminosity

Looking at your list Which characteristics show the strongest, most consistent relationship? Which graph incorporates the most data? – Can one characteristic tell you multiple things? – Mass – Temperature – Diameter – Color – Luminosity

Temperature v. Luminosity STRONG CORRELATION DIAMETER COLOR

Graph it! Plot each star as a letter K Careful!

H-R Diagram Add dots (general shape) M D B C E F G I J H N P L O K

Red Dwarf

Exit Question Give an example of an inverse relationship in humans.

Exit Question Where in the lifecycle of stars (example: beginning, middle, end) are: – White dwarves? – Red and super giants? I want to here your thoughts on this, you don’t know the correct answer yet