FARADAY ROTATION IN THE TAIL OF THE PLANETARY NEBULA DeHt 5
Bibliographic record
Abstract
We present 1420 MHz polarization images of a 5° × 5° region around the planetary nebula (PN) DeHt 5. The images reveal narrow Faraday-rotation structures on the visible disk of DeHt 5, as well as two wider, tail-like, structures "behind" DeHt 5. Though DeHt 5 is an old PN known to be interacting with the interstellar medium (ISM), a tail has not previously been identified for this object. The innermost tail is ∼3 pc long and runs away from the northeast edge of DeHt 5 in a direction roughly opposite that of the sky-projected space velocity of the white dwarf central star, WD 2218+706. We believe this tail to be the signature of ionized material ram-pressure stripped and deposited downstream during a >74,000 yr interaction between DeHt 5 and the ISM. We estimate the rotation measure (RM) through the inner tail to be −15 ± 5 rad m −2 , and, using a realistic estimate for the line-of-sight component of the ISM magnetic field around DeHt 5, derive an electron density in the inner tail of n e = 3.6 ± 1.8 cm −3 . Assuming the material is fully ionized, we estimate a total mass in the inner tail of 0.68 ± 0.33 M ☉ and predict that 0.49 ± 0.33 M ☉ was added during the PN–ISM interaction. The outermost tail consists of a series of three roughly circular components, which have a collective length of ∼11.0 pc. This tail is less conspicuous than the inner tail and may be the signature of the earlier interaction between the WD 2218+706 asymptotic giant branch (AGB) progenitor and the ISM. The results for the inner and outer tails are consistent with hydrodynamic simulations and may have implications for the PN missing-mass problem as well as for models which describe the impact of the deaths of intermediate-mass stars on the ISM.
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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 | 0.000 | 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) | 0.001 | 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".