What do you want to run?

The orbits are drawn for scale only.
The view keeps zooming in. The ruler down the left edge shows the stars closing.

How fast does gas arrive?

The white dwarf starts at 0.6 solar masses.

Both stars are 1.4 solar masses. There is nothing to set here.

Press the play button in the toolbar to run this star.

    Star Life Cycle

    You choose a star and play out its whole life. The periodic table beside it fills in with the elements that star creates.

    Data format

    Each finished run records one row. The row holds the starting mass, the companion, the ending, the lifetime, the heaviest element made, the count of new elements created, and the iron and gold released in Earth masses. Plot Star Mass against Iron Released to see which stars fill the Universe with iron.

    Model details
    • Stage lengths on screen are compressed unevenly. The strip below the panels shows the true time.
    • Tracks and yields are rounded to show the pattern. They are not measurement data.
    • The element table lights a square as soon as a star makes that element. Tap a square to read what makes that element and where in the star it forms.
    • A square takes the colour of the first process that made the element in your runs. Run a Sun first and carbon is blue. Run a massive star first and it is orange.
    • A massive star's supernova is credited with elements up to zirconium. Heavier ones come from dying low-mass stars and from merging neutron stars.
    • Stars above about 20 solar masses are shown collapsing straight to black holes. Real outcomes vary star by star.
    • Masses above 40 solar masses are not modelled, and neither are pair-instability supernovae.
    • Binary systems are drawn side-on and out of scale.
    • The Starlight card draws spectra from rounded line strengths. They are not measurements.
    How we know
    • Starlight carries a spectrum. Dark lines in that spectrum name the elements in a star and show how fast it is moving.
    • Technetium has no stable form, so any of it in a star was made there recently. Finding it in old giants is how slow neutron capture was confirmed.
    • In 2015 the evidence for this standard said supernovae make everything heavier than iron. In 2017 telescopes watched two neutron stars merge and measured the heavy elements thrown out. That observation revised the older claim, and this simulation shows the newer one.

    Standards

    • HS-ESS1-3: Communicate scientific ideas about the way stars, over their life cycle, produce elements.

    Design intent

    • One mass dial and one companion choice generate every outcome, so students meet the mass dependence the standard asks for instead of reading it.
    • The element table is cumulative across a session. Filling it takes several runs with different stars.
    • Tapping a square lists everything the model credits with making that element. Words such as most and about two thirds stand for shares rounded from Johnson (2019, Science 363:474) and Kobayashi, Karakas and Lugaro (2020, ApJ 900:179). About 67% of cobalt and 70% of nickel come from white-dwarf explosions. About 84% of zirconium comes from dying low-mass stars.
    • Sources differ on fluorine. Johnson's table credits massive-star explosions. Kobayashi and colleagues credit roughly half to dying low-mass stars. The sentence names both. It does not choose between them.
    • This model credits gold to merging neutron stars. Other explosions may add some, so the gold sentence does not claim gold has no other source.
    • The Temperature and brightness, Starlight and Inside the star cards sit behind the Astronomer's tools button. Leave it off for a simpler screen, or turn it on to read the star in more detail.
    • The Starlight card shows the surface of the star, not its core. The surface changes only where mixing or an explosion brings something up.
    • Line strength is not abundance. Hydrogen is most of every star, yet its lines are weakest in the coolest stars and strongest near 9500 kelvin. Payne (1925) showed this. Technetium in giants is from Merrill (1952). Strontium in a kilonova is from Watson and colleagues (2019, Nature 574:497).
    • The table is about what stars create. A red dwarf adds nothing to it, because it only makes helium and the Big Bang had already made helium.
    • Judging whether a claim still holds is the 9 to 12 practice here, so the About tab says plainly that a 2017 observation revised the older evidence statement.

    Discussion prompts

    • Which stars put gold into the Universe, and how many runs did it take to find one?
    • Does a heavier star always release more iron? Plot Star Mass against Iron Released and find out.
    • A red dwarf makes helium and never gives it back. What does that mean for the stars that come after it?

    How do I explore?

    1. Choose One star. Then set the starting mass, or press one of the named stars.
    2. Press the play button in the toolbar. The run stops at each key moment and explains what is happening.
    3. When the run ends, choose a different star and run it again.

    What should I do/notice?

    • Read the ruler down the left edge. A Sun-like star swells past Earth's orbit near the end.
    • Watch which part of the table lights up for each kind of star.
    • Find the star that releases gold. Only one of the three choices does.

    What about the data?

    Each finished run adds one row to your table. Plot Star Mass against Iron Released, or against Gold Released, to see which stars build which elements.