Photometric observations of R Coronae Borealis in the optical and infrared
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Bibliographic record
Abstract
The results of long-term photometric observations of R CrB in the UBV JHKLM bands are presented. The temporal and color characteristics of the emission of the star itself and of its extended dust envelope are analyzed in detail. No stable harmonic has been found in the semiregular variations of the optical brightness of R CrB. Two harmonics with periods P≈3.3 and 11.3 yrs have been detected in the brightness variations of the dust envelope; the minima of these variations coincided in 1999, resulting in a record decrease in the LM brightness of the envelope. This by chance coincided in time with a deep minimum of the visual brightness of the star, resulting in a unique decrease in the total brightness of the star and dust envelope. This enabled estimation of the bolometric flux of the hot dust clouds, which made up only a few per cent of the bolometric flux of the dust envelope. The brightness variations of the dust envelope are not accompanied by appreciable color changes and are associated with variations of its optical depth τ(V) in the range 0.2–0.4. The dust envelope forms at a large and fairly constant distance from the star $$(r_{in} \approx 110R_* ,T_{gr} \approx 860 K)$$ , from material in its stellar wind, whose intensity $$(\dot M_{gas} \approx 2.1 \times 10^{ - 7} M_ \odot /year)$$ obeys a Reimers law. No variations synchronous with those of the optical depth of the dust envelope, in particular, with the period P≈3.3 yrs, have been found in the optical emission of R CrB, suggesting that the stellar wind is not spherically symmetric. The dust envelope consists of small grains (a gr≤0.01 µm), while the clouds screening the star from the observer are made up of large grains (a gr≈0.1 µm). The activity of R CrB, whose nature is unclear, is reflected in variations of the stellar-wind intensity and the appearance of dust clouds in the line of sight: these variations are repeated by corresponding changes in the optical depth of the dust envelope with a delay of ∼4 years (the time for a particle moving at V env≈45 km/s to move from the star to the boundary of the dust envelope).
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Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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) | 0.000 | 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 it