Interactive formation sequence

Added to the existing hidden-protostars article on 11 October 2026. A native range input scrubs a deterministic canvas illustration from molecular cloud to main-sequence star. Nine milestone buttons, optional 24-second playback, reset and an explicitly labelled central cutaway support exploring the sequence.

The article includes _includes/starbirth-formation.html and the scoped public/css/starbirth-formation.css and public/js/starbirth-formation.js. No framework, external drawing library, image download, research observation or model training is used. Rendering is idle unless the reader scrubs, resizes or chooses playback; hidden-page playback pauses. Reduced-motion preference disables playback, retaining manual navigation. Canvas coordinates use one scale for both axes. The visual zoom changes as the cloud contracts; it is not a physical size axis, numerical collapse model or calibrated stellar clock.

Physics and scope

This is a representative low-mass/Sun-like pathway. It includes a contracting prestellar core, first hydrostatic core, molecular-hydrogen dissociation/second collapse, second-core formation, envelope accretion/clearing, disk evolution, pre-main-sequence contraction and sustained hydrogen fusion. First-core slow flows are possible/model-dependent. Class 0–III are approximate observational descriptions, not unambiguous ages or separate universal physical milestones. Fragmentation, inclination, stellar mass and overlapping processes prevent a universal one-dimensional clock. Deuterium burning can precede main-sequence hydrogen burning. The project’s birth definition remains second-core formation. Nothing in the illustration is a newly detected star or research result.

Sources are linked in the phase panel and caption:

• Young (2023), https://arxiv.org/abs/2312.03039 — first/second-core physics.
• Dunham et al. (2014), https://arxiv.org/abs/1401.1809 — protostars and envelopes.
• Ercolano & Pascucci (2017), https://arxiv.org/abs/1704.00214 — disk dispersal.
• Furlan et al. (2016), https://arxiv.org/abs/1602.07314 — classes/viewing angle.
• NASA stars, https://science.nasa.gov/universe/stars/ — main-sequence context.

Verification

docker compose run --rm build
node research/starbirth/check-formation.cjs _site_production
python3 research/starbirth/check_publication.py _site_production

The numerical checks cover bounded drawing parameters, all slider values, continuous transitions and inclusion/accessibility/asset wiring; they do not validate an astrophysical simulation. Supplement them with real pointer dragging, keyboard Home/End/arrows, all nine phase buttons, cutaway/reset, playback/pause, mobile layout, theme contrast and browser-console checks. Preserve the original compact-evidence inventory and unrelated user changes. Keep Git snapshots for implementation and verified publication separately.