Measuring the mass of the Milky Way using observations of radio waves emitted by neutral hydrogen
Bibliographic record
Abstract
In this experiment we studied the rotation of the spiral arms of the Milky Way and estimated its total mass by observing radio waves emitted from neutral hydrogen within the spiral arms. The spin-flip transition in a hydrogen atom results in the emission of a 21-cm radio wave that is Doppler-shifted when observed from Earth due to the hydrogen’s motion relative to Earth. We built a simple radio telescope composed of a horn antenna, a low noise amplifier, and a spectrometer made with gnu radio to observe the waves emitted within the first quadrant of the Milky Way. With these observations, we plotted a rotation curve of the Milky Way which had the expected logarithmic form and reasonable speeds when compared to the rotation curves from previous experiments. The mass distribution of the Milky Way was derived from the logarithmic fit and was evaluated at 129000 light-years to obtain a total mass of M = (1.5 ± 47 × 105) trillion solar masses. Our final result agrees with the expected mass of 𝑀𝑙𝑖𝑡𝑒𝑟𝑎𝑡𝑢𝑟𝑒 = 1.5 trillion solar masses. We attribute the large uncertainty on our calculated mass to the uncertainties in the parameters of our rotation curves fit to the logarithmic model.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".