Proper Motions in the Galactic Bulge: Plaut's Window
Bibliographic record
Abstract
A proper-motion study of a field of 20' × 20' inside Plaut's low-extinction window ( l , b ) = (0°, - 8°) has been completed. Relative proper motions and photographic BV photometry have been derived for ∼21,000 stars reaching to V ∼ 20.5 mag, based on the astrometric reduction of 43 photographic plates, spanning over 21 yr of epoch difference. Proper-motion errors are typically 1 mas yr -1 , and field-dependent systematics are below 0.2 mas yr -1 . Cross-referencing with the 2MASS catalog yielded a sample of ∼8700 stars, from which predominantly disk and bulge subsamples were selected photometrically from the JH color-magnitude diagram. The two samples exhibited different proper-motion distributions, with the disk displaying the expected reflex solar motion as a function of magnitude. Galactic rotation was also detected for stars between ∼2 and ∼3 kpc from us. The bulge sample, represented by red giants, has an intrinsic proper-motion dispersion of (σ l ,σ b ) = (3.39 ± 0.11,2.91 ± 0.09) mas yr -1 , which is in good agreement with previous results and indicates a velocity anisotropy consistent with either rotational broadening or triaxiality. A mean distance of 6.37 kpc has been estimated for the bulge sample, based on the observed K magnitude of the horizontal branch red clump. The metallicity [M/H] distribution was also obtained for a subsample of 60 bulge giants stars, based on calibrated photometric indices. The observed [M/H] shows a peak value at [M/H] ∼ -0.1 with an extended metal-poor tail and around 30% of the stars with supersolar metallicity. No change in proper-motion dispersion was observed as a function of [M/H]. We are currently in the process of obtaining CCD UBVRI photometry for the entire proper-motion sample of ∼21,000 stars.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.002 | 0.002 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".