Testing new ideas regarding the nature of interstellar extinction
Bibliographic record
Abstract
The nature of Galactic interstellar extinction is tested using reddening line parameters for several fields in conjunction with equivalent widths W(λ4430) for the diffuse interstellar band at 4430 Å. The Cardelli et al. relations (Astrophys. J. 345, 245 (1989). doi:10.1086/167900) at infrared, optical, and ultraviolet wavelengths are inconsistent with the newly-derived quadratic variation of RV(observed) on reddening slope X. A minimum of RV = 2.82 ± 0.06 exists for X = 0.83 ± 0.01, and is argued to represent true Galactic extinction described by A(λ) ∝ λ–1.375. It matches expectations for a new description of extinction in the infrared, optical, and ultraviolet by Zagury (Astron. Nachr. 334, 1107 (2013)). Additional consequences, reddened stars with no 2175 Å feature and a correlation of normalized λ4430 absorption with X, are not predicted by the Cardelli et al. relation (Astrophys. J. 345, 245 (1989). doi:10.1086/167900 ). Known variations in X from 0.62 to 0.83, and corresponding variations in RV(observed) from 4.0 to 2.8, presumably result from forward-scattered starlight in the ultraviolet contaminating optical light of stars affected by dust extinction. A new understanding of the true nature of interstellar extinction is important for establishing an accurate picture of the extragalactic distance scale, which in turn is related to our understanding of the nature of the Universe.
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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 | 0.019 | 0.081 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.001 | 0.010 |
| Scholarly communication | 0.007 | 0.017 |
| Open science | 0.005 | 0.004 |
| Research integrity | 0.003 | 0.006 |
| Insufficient payload (model declined to judge) | 0.007 | 0.001 |
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".