The Resolved Narrow‐Line Region in NGC 4151
Bibliographic record
Abstract
We present slitless spectra of the narrow-line region (NLR) in NGC 4151 from the Space Telescope Imaging Spectrograph (STIS) on the Hubble Space Telescope and investigate the kinematics and physical conditions of the emission-line clouds in this region. Using medium resolution (~0.5 Å) slitless spectra at two roll angles and narrow-band undispersed images, we have mapped the NLR velocity field from 1.2 kpc to within 13 pc ( H 0 = 75 km s -1 Mpc -1 ) of the nucleus. The inner biconical cloud distribution exhibits recessional velocities relative to the nucleus to the NE and approaching velocities to the SW of the nucleus. We find evidence for at least two kinematic components in the NLR. One kinematic component is characterized by low velocities and low velocity dispersions (LVLVD clouds: ∣ v ∣ < 400 km s -1 , and Δ v < 130 km s -1 ). This population extends through the NLR, and their observed kinematics may be gravitationally associated with the host galaxy. Another component is characterized by high velocities and high velocity dispersions (HVHVD clouds: 400 < ∣ v ∣ ≲ 1700 km s -1 , Δ v ≥ 130 km s -1 ). This set of clouds is located within 1 1 (~70 pc) of the nucleus and has radial velocities that are too high to be gravitational in origin but show no strong correlation between velocity or velocity dispersion and the position of the radio knots. Outflow scenarios will be discussed as the driving mechanism for these HVHVD clouds. We also find clouds characterized by low velocities and high velocity dispersions (LVHVD clouds: ∣ v ∣ < 400 km s -1 , Δ v ≥ 130 km s -1 ). These clouds are located within 3 2 (~200 pc) of the nucleus. It is not clear if the LVHVD clouds are HVHVD clouds whose low velocities are the result of projection effects. Within 3 2 (~200 pc) of the nucleus, the [O III]/Hβ ratio declines roughly linearly for both the high-velocity-dispersion (HVD) and LVLVD clouds. Since the ionization parameter is proportional to r -2 n -1 , it appears that the density, n , must decrease as ~ r -1 for the clouds within the inner ~3 2. At distances further from the nucleus, the [O III]/Hβ ratio is roughly constant.
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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 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 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".