Origins of the Elements: We Are Stardust

Standards Alignment:

• Performance Expectation: HS-ESS1-3
• Science and Engineering Practice: Obtaining, Evaluating, and Communicating Information
• Disciplinary Core Ideas: ESS1.A: The Universe and Its Stars
• Crosscutting Concept: Energy and Matter

Simulation Link: Stellar Nucleosynthesis Explorer

Introduction: The Cosmic Connection

Famous astronomer Carl Sagan once said, “The nitrogen in our DNA, the calcium in our teeth, the iron in our blood, the carbon in our apple pies were made in the interiors of collapsing stars. We are made of starstuff.”

In this investigation, you will use the Stellar Nucleosynthesis Explorer to verify this claim and trace the origins of the atoms that make up you and the world around you.

Part 1: Stellar Lifetimes and Mass

1. Low-Mass vs. High-Mass Stars:
   • Set the Initial Star Mass to 1.0 Solar Masses (similar to our Sun).
   • Click Play and watch the star evolve. Record the final remnant of the star: ________
   • Now, Reset and set the mass to 25.0 Solar Masses. Play the simulation. Record the final stage/remnant of this star: ________
   • Analyze: Which star type (low mass or high mass) lives for a longer percentage of “cosmic time” relative to its fuel supply? (Hint: Look at the speed of the “Stellar Age” slider during Play).
2. Core Temperature:
   • Compare the Core Temp of the 1.0 Solar Mass star during its “Main Sequence” stage to the 25.0 Solar Mass star during its “Main Sequence” stage.
   • Explain the relationship between a star’s initial mass and its core temperature.

Part 2: The Fusion Factory (H → Fe)

1. Investigating Low-Mass Fusion:
   • Run the 1.0 Solar Mass star again. Look at the Elements Produced/Present panel.
   • List the elements produced by a star of this mass: ________
   • According to the simulation, does a 1.0 Solar Mass star ever produce Iron (Fe)? Why or why not?
2. Investigating High-Mass Fusion:
   • Run the 25.0 Solar Mass star. Pause the simulation during the Red Supergiant stage.
   • List the “Layers” or elements being produced in the core now: ________
   • The Iron “Wall”: The simulation notes that fusion up to iron releases energy. Based on the “Stellar Diagnostics” panel, what is the core temperature required to reach the Iron (Fe) stage?

Part 3: Supernova and Extreme Elements

1. Beyond Iron:
   • Watch the 25.0 Solar Mass star reach 100% Age (the Supernova stage).
   • Look at the Elements Produced in the supernova blast. Record at least two elements that were not present during the Red Supergiant stage: ________
   • Explain: If the star’s core has collapsed and fusion has “stopped,” how are these heavy elements like Gold (Au) or Uranium (U) formed? (Hint: Read the description in the tooltip or log).

Part 4: The Law of Conservation (Nucleon Accounting)

1. Nucleon Conservation Analysis:
   • Reset the simulation to 1.0 Solar Masses and move the age to the Main Sequence (H → He).
   • Look at the Nucleon Conservation Analysis panel.
   • Record the reactants and products:
     • Reactants: __ Protons (P), __ Neutrons (N)
     • Products: __ Protons (P), __ Neutrons (N)
   • The Principle: In your own words, explain how the identity of the atoms changed (e.g., from Hydrogen to Helium), yet the total amount of matter (protons + neutrons) remained the same.

Part 5: Communicating Scientific Ideas

Writing Task: A Stellar Biography

Choose one element found in the human body (e.g., Oxygen in your lungs, Carbon in your tissues, or Iron in your blood). Write a short paragraph (3-5 sentences) “communicating” the life cycle of that atom.

Your biography must include:

• The type of star (Low or High mass) required to forge it.
• The specific fusion reaction or stage that produced it.
• How that element was eventually “released” from the star to become part of a planet (and eventually, you).