THE OPTICAL–INFRARED EXTINCTION CURVE AND ITS VARIATION IN THE MILKY WAY
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Bibliographic record
Abstract
ABSTRACT The dust extinction curve is a critical component of many observational programs and an important diagnostic of the physics of the interstellar medium. Here we present new measurements of the dust extinction curve and its variation toward tens of thousands of stars, a hundred-fold larger sample than in existing detailed studies. We use data from the APOGEE spectroscopic survey in combination with ten-band photometry from Pan-STARRS1, the Two Micron All-Sky Survey, and Wide-field Infrared Survey Explorer . We find that the extinction curve in the optical through infrared is well characterized by a one-parameter family of curves described by R ( V ). The extinction curve is more uniform than suggested in past works, with <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>σ</mml:mi> <mml:mo stretchy="true">(</mml:mo> <mml:mi>R</mml:mi> <mml:mo stretchy="true">(</mml:mo> <mml:mi>V</mml:mi> <mml:mo stretchy="true">)</mml:mo> <mml:mo stretchy="true">)</mml:mo> <mml:mo>=</mml:mo> <mml:mn>0.18</mml:mn> </mml:math> , and with less than one percent of sight lines having <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>R</mml:mi> <mml:mo stretchy="true">(</mml:mo> <mml:mi>V</mml:mi> <mml:mo stretchy="true">)</mml:mo> <mml:mo>></mml:mo> <mml:mn>4</mml:mn> </mml:math> . Our data and analysis have revealed two new aspects of Galactic extinction: first, we find significant, wide-area variations in R ( V ) throughout the Galactic plane. These variations are on scales much larger than individual molecular clouds, indicating that R ( V ) variations must trace much more than just grain growth in dense molecular environments. Indeed, we find no correlation between R ( V ) and dust column density up to <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>E</mml:mi> <mml:mo stretchy="true">(</mml:mo> <mml:mi>B</mml:mi> <mml:mo>−</mml:mo> <mml:mi>V</mml:mi> <mml:mo stretchy="true">)</mml:mo> <mml:mo>≈</mml:mo> <mml:mn>2</mml:mn> </mml:math> . Second, we discover a strong relationship between R ( V ) and the far-infrared dust emissivity.
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Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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) | 0.000 | 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 it