HZ HER: STELLAR RADIUS FROM X-RAY ECLIPSE OBSERVATIONS, EVOLUTIONARY STATE, AND A NEW DISTANCE
Bibliographic record
Abstract
Observations of HZ Her/Her X-1 by the Rossi X-Ray Timing Explorer ( RXTE ) covering high state eclipses of the neutron star are analyzed here. Models of the eclipse are used to measure the radius and atmospheric scale height of HZ Her, the stellar companion to the neutron star. The radius is 2.58–3.01 × 10 11 cm, depending on system inclination and mass ratio ( q ), with an accuracy of ∼1 part in 1000 for given inclination and q . We fit Kurucz model stellar atmosphere models to archival optical observations. The resulting effective temperature ( T eff ) of the unheated face of HZ Her is determined to be in the 2σ range of 7720 K–7865 K, and metallicity (log ( Z / Z ☉ )) in the range of −0.27 to +.03. The model atmosphere surface flux and new radius yield a new distance to HZ Her/Her X-1, depending on system inclination and q : a best-fit value of 6.1 kpc with upper and lower limits of 5.7 kpc and 7.0 kpc. We calculate stellar evolution models for the range of allowed masses (from orbital parameters) and allowed metallicities (from optical spectrum fits). The stellar models agree with T eff and the radius of HZ Her for two narrow ranges of mass: 2.15–2.20 M ☉ and 2.35–2.45 M ☉ . This lower mass range implies a low neutron star mass (1.3 M ☉ ), whereas the higher mass range implies a high neutron star mass (1.5–1.7 M ☉ ).
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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 | 0.001 |
| 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 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
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".