Resolving OB Systems in the Carina Nebula with the<i>Hubble Space Telescope</i>Fine Guidance Sensor
Bibliographic record
Abstract
We observed 23 OB stars in the Carina Nebula (NGC 3372) with the Hubble Space Telescope 's Fine Guidance Sensor 1r (FGS1r) in its high angular resolution mode. Five of these OB stars are newly resolved binaries with projected separations ranging from 0 015 to 0 352 (37 to 880 AU at a distance of 2.5 kpc), and V -band magnitude differences ranging from 0.9 to 2.8. The most important astrophysical result is the unexpected resolution of the prototype O2 If* star HD 93129A as a 55 milliarcsecond (mas) double with a Δ m V of 0.9. This object has served as a spectroscopic benchmark for the analysis of the most massive hot stars and their winds on the prior assumption that it is a single star. This discovery supports the interpretation of recent radio and X-ray observations as evidence of colliding-wind phenomena in HD 93129A. Another interesting result is the determination of an upper limit of about 35 AU for the projected separation of the binary pairs in the hierarchical double spectroscopic binary HD 93206. The high incidence of resolved binaries provides motivation for a more thorough, statistically meaningful study of multiplicity among the most massive stars in the young ionizing clusters of the nebula to obtain a complete sample of the long-period systems that have evaded spectroscopic detection. However, considering that the nine spectroscopic binaries with accurate orbits in the Carina Nebula have orbital dimensions ≲1 AU, which at a distance of 2.5 kpc subtends an angle of only 0.4 mas, well below the ≃10 mas angular resolution of FGS1r, there remains a significant range of orbital periods and separations over which it is very difficult to detect multiplicity in the nebula with currently available instruments.
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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 | 0.000 |
| 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".