First ALMA maps of HCO, an important precursor of complex organic molecules, towards IRAS 16293–2422
Bibliographic record
Abstract
The formyl radical HCO has been proposed as the basic precursor of many complex organic molecules such as methanol (CH 3 OH) or glycolaldehyde (CH 2 OHCHO).Using ALMA, we have mapped, for the first time at high angular resolution (∼1 ′′ , ∼140 au), HCO towards the Solar-type protostellar binary IRAS 16293-2422, where numerous complex organic molecules have been previously detected.We also detected several lines of the chemically related species H 2 CO, CH 3 OH and CH 2 OHCHO.The observations revealed compact HCO emission arising from the two protostars.The line profiles also show redshifted absorption produced by foreground material of the circumbinary envelope that is infalling towards the protostars.Additionally, IRAM 30m single-dish data revealed a more extended HCO component arising from the common circumbinary envelope.The comparison between the observed molecular abundances and our chemical model suggests that whereas the extended HCO from the envelope can be formed via gas-phase reactions during the cold collapse of the natal core, the HCO in the hot corinos surrounding the protostars is predominantly formed by the hydrogenation of CO on the surface of dust grains and subsequent thermal desorption during the protostellar phase.The derived abundance of HCO in the dust grains is high enough to produce efficiently more complex species such as H 2 CO, CH 3 OH, and CH 2 OHCHO by surface chemistry.We found that the main formation route of CH 2 OHCHO is the reaction between HCO and CH 2 OH.
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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) | 0.002 | 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".