Illuminating a tadpole’s metamorphosis II: observing the ongoing transformation with ALMA
Bibliographic record
Abstract
ABSTRACT We present new Atacama Large Millimeter/submillimeter Array observations of the tadpole, a small globule in the Carina Nebula that hosts the HH 900 jet+outflow system. Our data include 12CO, 13CO, C18O J=2–1, 13CO, C18O J=3–2, and serendipitous detections of DCN J=3–2 and CS J=7–6. With angular resolution comparable to the Hubble Space Telescope, our data reveal for the first time the bipolar molecular outflow in CO, seen only inside the globule, that is launched from the previously unseen jet-driving protostar (the HH 900 YSO). The biconical morphology joins smoothly with the externally irradiated outflow seen in ionized gas tracers outside the globule, tracing the overall morphology of a jet-driven molecular outflow. Continuum emission at the location of the HH 900 YSO appears to be slightly flattened perpendicular to outflow axis. Model fits to the continuum have a best-fitting spectral index of ∼2, suggesting cold dust and the onset of grain growth. In position–velocity space, 13CO and C18O gas kinematics trace a C-shaped morphology, similar to infall profiles seen in other sources, although the global dynamical behaviour of the gas remains unclear. Line profiles of the CO isotopologues display features consistent with externally heated gas. We estimate a globule mass of ∼1.9 M⊙, indicating a remaining lifetime of ∼4 Myr, assuming a constant photoevaporation rate. This long globule lifetime will shield the disc from external irradiation perhaps prolonging its life and enabling planet formation in regions where discs are typically rapidly destroyed.
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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 | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 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".