HST Observations of the Main Sequence of M4
Bibliographic record
Abstract
This paper presents new results from a photometric study of the main-sequence stars in M4, the closest globular cluster to the sun. Multi-field, multi-epoch observations at approximately 1, 2, and 6 core-radii were obtained with the WFPC2 camera on the HST. The multi-epoch observations allowed us to clean the data on the basis of proper motion. In all the fields the cluster main sequence can be traced to at least V = 27.0 but there remains a trail of stars to the limit of the data near V = 30 in the deepest outer field. There is no evidence that we have reached the end of the hydrogen burning main sequence in any of our fields, however, there is some indication that very few stars remain to be detected in the deepest data. The scatter about the cluster main sequence yields a surprisingly small and variable binary fraction; f_b = 2% in the inner parts of the cluster falling to the 1% range outside. For the currently visible main sequence stars, the cluster mass function is very flat (alpha =0.1) in the outer field and flattens further in the inner fields suggesting well developed mass segregation. The observed variation in the mass function is broadly consistent with isotropic, multi-mass Michie-King models. Because we have a large sample of white dwarfs in the outer field we are able to show that the cluster IMF above 0.8Msun was considerably steeper than the present day mass function for low mass stars. Two appendicies are included in this contribution; a detailed discussion of the techniques used to reduce the data and a direct comparison between the cluster stars and those belonging to the inner spheroid of the Galaxy yielding a Galactocentric distance of 7.5+/-0.6 kpc.
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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 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| 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) | 0.002 | 0.001 |
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".