Multiscale Magnetic Fields in Star‐forming Regions: Interferometric Polarimetry of the MMS 6 Core of OMC‐3
Bibliographic record
Abstract
We present the first interferometric observations of linearly polarized emission toward the OMC-3 region of the Orion A cloud. We have observed the MMS 6 protostellar core at 1.3 mm with the Berkeley-Illinois-Maryland Association (BIMA) array, achieving a resolution of 4 3 × 3 0. We find that the polarization angle measured changes systematically across the core, orienting along a dust extension to the northwest. The polarization angle is oriented similarly to the 850 and 350 μm polarized emission measured by the SCUBA and Hertz polarimeters. A polarization hole is detected, as is typical of polarized emission data toward cores. Since the BIMA data are insensitive to structure on spatial scales of >40'', the emission detected is dominated by the core and not the integral-shaped filament in which it is embedded. Observations of CO J = 2-1 reveal CO emission potentially associated with the core, but no outflow signature is detected. Utilizing the Chandrasekhar-Fermi method, we have used the dispersion in the polarization vectors to estimate a field strength of 640 μG in the plane of the sky, assuming a corrective Q -factor of 0.5. Applying the recent measurement of the inclination of the field to the line of sight (Houde et al.), a total field strength of 680 μG is derived. Despite highly nonthermal line widths, the kinetic energy density is found to be insufficient to support this core against gravitational collapse. The magnetic energy density, when combined with the predominantly turbulent kinetic energy density, is comparable to the effects of gravity, but its value is highly dependent on the applied Q -factor to a degree that the core may be subcritical or supercritical. The preservation of the field geometry from large to small scales in this core is consistent with observations of a second protostellar core in a filamentary cloud in Orion B.
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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 | 0.001 |
| 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".