Filamentary structures of ionized gas in Cygnus X
Bibliographic record
Abstract
Context.Ionized gas probes the influence of massive stars on their environment. The Cygnus X region (d~ 1.5 kpc) is one of the most massive star-forming complexes in our Galaxy, within which the Cyg OB2 association (age of 3–5 Myr and stellar mass 2 × 104M⊙) has a dominant influence. Aims.We observe the Cygnus X region at 148 MHz using the Low Frequency Array (LOFAR) and take short-spacing information into account during image deconvolution into account. Together with data from the Canadian Galactic Plane Survey, we investigate the morphology, distribution, and physical conditions of low-density ionized gas in a 4° × 4° (~100 pc × 100 pc) region at a resolution of 2′ (0.9 pc). Methods.The Galactic radio emission in the region analyzed is almost entirely thermal (free-free) at 148 MHz, with emission measures (EM) of 103< EM [pc cm−6] < 106. As filamentary structure is a prominent feature of the emission, we use DisPerSE and Fil ChaP to identify filamentary ridges and characterize their radial (EM) profiles. Results.The distribution of radial profiles has a characteristic width of 4.3 pc and a power-law distribution (β= −1.8 ± 0.1) in peak EM down to our completeness limit of 4200 pc cm−6. The electron densities of the filamentary structure range between 10 ≲ne[cm−3] ≲ 400 with a median value of 35 cm−3, remarkably similar to [N II] surveys of ionized gas. Conclusions.Cyg OB2 may ionize at most two-thirds of the total ionized gas and the ionized gas in filaments. More than half of the filamentary structures are likely photoevaporating surfaces flowing into a surrounding diffuse (~5 cm−3) medium. However, this is likely not the case for all ionized gas ridges. A characteristic width in the distribution of ionized gas indicates that the stellar winds of Cyg OB2 create a fraction of the ionized filaments through swept-up ionized gas or dissipated turbulence.
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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) | 0.001 | 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".