<i>Far Ultraviolet Spectroscopic Explorer</i>Survey of the Local Interstellar Medium within 200 Parsecs
Bibliographic record
Abstract
We present Far Ultraviolet Spectroscopic Explorer observations of the interstellar gas toward 30 white dwarf stars and one subdwarf (SdO) star. These sight lines probe the Local Bubble (LB) and the local interstellar medium (LISM) near the LB. We systematically measure the column densities for the following species: C II, C II*, C III, N I, N II, O I, Ar I, Si II, P II, Fe II, Fe III, and H 2 . Our survey detected only diffuse H 2 molecular clouds ( f H 2 ≲ 10 -4 ) along six sight lines. There is no evidence from this study that H 2 exists well inside the perimeter of the LB. The kinematical temperature for H 2 is less than the usual temperature observed in the local interstellar clouds, implying different gas phases in the LISM. The relative abundance ratios of Si II, P II, and Fe II give insight about the dust content. These ratios vary but are similar to the depletion patterns observed in warm and halo diffuse clouds in more distant sight lines in the Galaxy. The N I/O I and Ar I/O I ratios are significantly subsolar within the LB. Outside the LB a larger scatter is observed from subsolar to solar. Because Ar and N are only weakly depleted into dust grains if at all, the deficiencies of their neutral forms are likely due to photoionization. The evidence for significant ionization of N (and hence Ar) is strengthened by the detection and measurement of N II, which is a dominant ion for this element toward many sight lines. C III appears to be ubiquitous in the LISM toward our sight lines, but C II remains the dominant ionization stage of C. The limits on Fe III/Fe II imply that Fe II is the dominant ion. These observations imply that photoionization is the main ionization mechanism in the LISM and do not support the existence of a highly ionized condition in the past. In view of the variations observed in the different atomic and ionic ratios, the photoionization conditions vary significantly in the LB and the LISM. The cooling rate in the LISM, l c [in ergs s -1 (H I atom) -1 ], derived from the emission of the C II 157.7 μm line has a mean value of log l c = -25.59 ± 0.32 dex, very similar to previous determinations.
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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 | 0.002 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.011 | 0.002 |
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".