Magnetic Fields in Massive Star-forming Regions (MagMaR): Unveiling an Hourglass Magnetic Field in G333.46–0.16 Using ALMA
Bibliographic record
Abstract
Abstract The contribution of the magnetic field to the formation of high-mass stars is poorly understood. We report the high angular resolution (∼0.″3, 870 au) map of the magnetic field projected on the plane of the sky (B POS) toward the high-mass star-forming region G333.46−0.16 (G333), obtained with the Atacama Large Millimeter/submillimeter Array at 1.2 mm as part of the Magnetic fields in Massive star-forming Regions survey. The B POS morphology found in this region is consistent with a canonical “hourglass” with an embedded flattened envelope in a perpendicular direction, which suggests a dynamically important field. This region is fragmented into two protostars that appear to be gravitationally bound in a stable binary system with a separation of ∼1740 au. Interestingly, by analyzing H13CO+ (J = 3–2) line emission, we find no velocity gradient over the extent of the continuum, which is consistent with a strong field. We model the B POS, obtaining a marginally supercritical mass-to-flux ratio of 1.43, suggesting an initially strongly magnetized environment. Based on the Davis–Chandrasekhar–Fermi method, the magnetic field strength toward G333 is estimated to be 5.7 mG. The absence of strong rotation and outflows toward the central region of G333 suggests strong magnetic braking, consistent with a highly magnetized environment. Our study shows that despite being a strong regulator, the magnetic energy fails to prevent the process of fragmentation, as revealed by the formation of the two protostars in the central region.
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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) | 0.001 | 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".