Galactic chemical evolution
Galactic chemical evolution
Stars inherit the composition of their birth gas. Follow where that material goes, why sources arrive on different schedules, and how a chemical track becomes a measured stellar population.
L1
Why magnesium and iron remember star formation
Stars retain clues to when their gas was enriched. Learn why magnesium and iron respond differently, and why their ratio is not a unique clock.
L1
Follow the gas and the newly made elements
Build a one-zone mass budget, distinguish recycled material from net yields, and derive why a well-mixed wind need not lower abundance at fixed time.
L2
Calculate a delayed enrichment track
Derive a closed-box control, normalize a delay-time distribution, and calculate how past star formation supplies present magnesium and iron.
L3
From a gas track to a stellar abundance population
Weight a chemical track by stellar birth mass, propagate shared iron errors, and build a normalized conditional density for measured abundances.
L3
Recompute a fixed Sculptor abundance sample
Run an independent one-zone calculation, validate birth-mixture integration, and locally extract a fixed 99-star source with 96 usable abundance pairs.
L4
Delayed sources and imperfect mixing
Read a fixed 2026 dwarf-galaxy study through its figures: Ia delay, r-process source degeneracies, yield sensitivity and failures of a mixed one-zone model.
Standalone scientific materials
Download the scientific ZIP · Read setup and calculation scope
The offline calculation needs Python, NumPy and SciPy. It solves four histories and compares saved synthetic measurements. Optional fixed Hill extraction runs locally with pdftotext; the ZIP has no original observations, paper or browser Engine.
Individual scripts, sizes and SHA-256
- README.md (5754 B)
5a638f0c540b5d489ab149d2af7b8713a376a85a66f6a1a241a57052fee5ea1a - LICENSE.txt (1271 B)
c8d56106a2c4041b440e94509790c6403bbad8908db7efdbf09bbfe4c893ce82 - requirements.txt (27 B)
39b93fa1b8397265839a510ca7601608248a7f3524067b61667e977bf4351475 - source-identities.json (1618 B)
f7d7dc4c91ee350ab7f809a2c4c54c7f2e6c650a87e3b4b7476cdaa1c59ed127 - fixed-inputs.json (533 B)
98aaf54949a88e6ee5e4697b5ff25050bfff5790faa17d6d6ee5b7b02f9f1ac2 - model-family.json (537 B)
58dac14f9a01ed44a43c4d45dc88e12aa76c9a26c5fd977940099811242751a4 - own-observations.json (10029 B)
3c2f318702cf26a370d4d298b8e4ed37da26e19c5052d51ef9a0daee06dba2f0 - compare.py (3237 B)
785b41dd356c57e90165197b70ec11adf6271daafe85e096e793f237bcc2c860 - evolution.py (4572 B)
4deabefc6e7087e882bf44fe43b582762ba461d08c634d7e5237615760fcf108 - extract_hill.py (2549 B)
59aa4cd821574c65110549c41e513fe7161210789c319eeb9342b26d659598d3 - fetch_hill.py (1705 B)
d31ccb38d10b8cd8a90194ba6a6d5b3e97af81b41c3dbef903c48ecc9b413696 - io_helpers.py (1894 B)
2a07f3ab2f0792f19d5575e5fbb38a6d1370df6e01c20c1cde0a3e2fa072a959 - make_observations.py (1327 B)
5498e13a03606dc0adf97488f0f1d1bef92f04ed275aa16f7fe111a0d5683e79 - make_records.py (1461 B)
3f25e9ee127836c6e2ade3f922de38941ca941bf26ebd9c85bf21538655b611a - make_reference.py (4034 B)
cb0b779f168fe6e8ec93614da0eae1de7f82c37d61a632f05b5e987fe4e14f69 - observation_quadrature.py (1662 B)
5b1ad8917ef50bff8a63248c883e5b56f72875eaa49470b41d98db44ca21186a - plot.py (3976 B)
55f9242160e7bd86321117136b5fc12a735c39cb1d5ae2ccd57481f76fb2ec6d - validate.py (7153 B)
1e089465eae28b0bcbf8bf9e696c3ccd7e07a645bcf7173cb536c72e878e5c00 - verify_package.py (926 B)
16d0c1b6185e7107b33fd33639456aa4806f3984269ca671f9b1b70bf487cd3d - SHA256SUMS.json (3112 B)
28a1797407ef24a767fde830473a49ca5d8ddb675f13ce03135ba1a2fe4b567a - chemical-evolution-science-v1.zip (26888 B)
63dc82bb31bcd276c9abc76191e3201804d13d068811c5ff27bd244b17dcc06d
Sources and calculation scope
- Weinberg, Andrews & Freudenburg, Equilibrium and Non-Equilibrium Aspects of Galactic Chemical Evolution, arXiv:1604.07435v1
Complete fixed 30-page paper read again, including both appendices. Net yields, recycled material and analytic controls follow sections 2–3; delay approximations and birth weighting follow section 5. Its oxygen and exponential-delay examples are not silently relabeled as our fixed magnesium and finite power-law kernel. Its gas-linked formation law differs from our prescribed histories.
- Hill et al., VLT/FLAMES high-resolution chemical abundances in Sculptor, arXiv:1812.01486v2
Main sections 1–7 and appendices A/B read again; Table C5 extracted in two text modes with exact agreement on 99 rows and 96 finite Mg/Fe pairs. Methods specify the 25-arcminute-diameter field and upper-RGB selection; conclusions use inconsistent radius wording. Full per-star covariance and a numerical model-solar harmonization are not established here. Original observations, PDF and measured-derived figures remain local.
- VICE v1.3.1 fixed effective yields and solar reference
Previously frozen native defaults: Kroupa convention, effective net core-collapse and Type Ia magnesium/iron yields, Asplund 2009 reference and the declared hydrogen conversion. Public materials contain scalar values and identities, not a new yield grid or VICE executable. The independent Python does not execute VICE.
- Henderson, Kirby, de los Reyes & Surman, Constraints on the r-process Delay Time from Dwarf Spheroidal Galaxies, arXiv:2610.15946v1
Full fixed 24-page preprint, both appendices, Figures 1–12 and Tables 1–4 read; source figures and tables visually inspected. Posted 11 October 2026, internal draft 14 October. Actual PDF SHA-256 is 25e460e527705c40f64feaf0bc06e0a840f8967b67fed681c3acec5ad71ebcdc; server ETag differs and is not treated as a content signature. This is a primary-paper guide, not a rerun of its multi-element sampling or an identification of r-process sites. Original PDF and figures are not redistributed.
- Independent one-zone chemical-evolution Python materials
Original continuous convolution/DOP853 producers, saved fourteen-field inventories and birth populations, finite refinement, normalized conditional mixtures and mathematical limits. Public inputs and figures are original synthetic data. Default is offline; optional fixed Hill source is fetched and analyzed on the reader’s computer. No App/Engine, original paper, observed rows or measured-derived plot is included.