Life of a star, and red shift sim
Slide galaxy-spectrum slides into a viewer beside a school spectrometer and hydrogen tube, put a cursor on each galaxy's red hydrogen line, work out its shift and graph it against distance; then drag a star-life model set's mass slider and step through the life of a star like the Sun and of a much more massive one.
Stars and the Universe: the life cycle of a star; red shift and the expanding Universe · covers the IGCSE, GCSE topic
What the sim shows
Model: a galaxy at distance d moves away at v = H0 × d (H0: the syllabus's current estimate; 1 light-year = 9.5 × 10¹⁵ m); every line in its light is moved to λ × (1 + v ÷ c) (c = 3.0 × 10⁸ m/s; this form is beyond the syllabus). Lab hydrogen lines 656.3, 486.1, 434.0 and 410.2 nm (from memory); four chosen galaxies at 150 to 900 million light-years. Life of a star: the syllabus's stages, for a star about the size of the Sun and for a much more massive one (dividing masses about 8 and 25 Sun-masses, beyond the syllabus, from memory). Not to scale. Nothing runs on its own.
- Red shift: the slide carriage. Life of a star: the mass slider's knob
- A school spectrometer with a hydrogen tube and a slide viewer; a star-life model set
Use it in your lessons
- Try it here: anyone can unlock 2 figures free, and a free account unlocks up to 5. Runs on a laptop, a Chromebook or a phone; nothing to install.
- Present it and share student links with the teacher plan, from US$5 a month, billed yearly.
- Put it on your own website or LMS for US$9, paid once, or every sim from US$29 a month.
Free guide: 12 practicals as sims, and how to run one in a lesson →
Need a version for your exact set-up? Have one made: US$49 a figure in an order of 5.
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