RESOLVED DEPLETION ZONES AND SPATIAL DIFFERENTIATION OF N<sub>2</sub>H<sup>+</sup>AND N<sub>2</sub>D<sup>+</sup>
Bibliographic record
Abstract
We present a study on the spatial distribution of N 2 D + and N 2 H + in 13 protostellar systems. Eight of thirteen objects observed with the IRAM 30 m telescope show relative offsets between the peak N 2 D + ( J = 2 → 1) and N 2 H + ( J = 1 → 0) emission. We highlight the case of L1157 using interferometric observations from the Submillimeter Array and Plateau de Bure Interferometer of the N 2 D + ( J = 3 → 2) and N 2 H + ( J = 1 → 0) transitions, respectively. Depletion of N 2 D + in L1157 is clearly observed inside a radius of ∼2000 AU (7'') and the N 2 H + emission is resolved into two peaks at radii of ∼1000 AU (3 5), inside the depletion region of N 2 D + . Chemical models predict a depletion zone in N 2 D + and N 2 H + due to destruction of H 2 D + at T ∼ 20 K and the evaporation of CO off dust grains at the same temperature. However, the abundance offsets of 1000 AU between the two species are not reproduced by chemical models, including a model that follows the infall of the protostellar envelope. The average abundance ratios of N 2 D + to N 2 H + have been shown to decrease as protostars evolve by Emprechtinger et al., but this is the first time depletion zones of N 2 D + have been spatially resolved. We suggest that the difference in depletion zone radii for N 2 H + and N 2 D + is caused by either the CO evaporation temperature being above 20 K or an H 2 ortho-to-para ratio gradient in the inner envelope.
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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 | 0.001 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.004 | 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".