A Search for Faint Companions to Nearby Stars Using the Wide Field Planetary Camera 2
Bibliographic record
Abstract
We have completed a direct-imaging search for faint companions (FCs) to 23 stars within 13 pc of the Sun using the Hubble Space Telescope Planetary Camera. The strategy of this search changed considerably from that reported in 1996. To maximize the image contrast between potential FCs and a target star's point-spread function, we adopted the F1042M filter (λ c ∼ 1.02 μm, Δλ ∼ 0.04 μm) as the primary bandpass of our search. Although our sensitivity to FCs varied with the brightness of and separation from our target stars, an ultimate 10 σ detection limit of m 1042 ≈ 18 within 17'' of the fainter targets was achieved. As the end of the main sequence occurs at M 1042 ≈ 12, this detection limit makes our search for FCs to nearby stars the most sensitive yet published. Despite this great sensitivity, no previously undetected FCs were found. Our survey would have detected all stellar companions within 17'' of our target stars, except for any lowest mass companions lying within 0 5–1'' of the brightest ( V < 1.5) targets. Applying recent models of brown dwarf spectra and evolution, we find that our search was sensitive to young (0.5 Gyr), low-mass (less than 10 M J ) brown dwarf companions to the fainter targets within 5 pc. A brown dwarf with mass 40 M J and age 5 Gyr would have been detected at separations greater than 5'' from Gl 559A (α Centauri A). Our search was not sensitive to 1 Gyr–old brown dwarfs with masses ≲5 M J , nor was it sensitive to 5 Gyr–old brown dwarfs with masses ≲10 M J . On the positive side, we show the first direct image of the triple system GJ 1245ABC in which all three components are well resolved. Multiband photometry of GJ 1245C suggests for that object a spectral type later than M7. The measured positions of GJ 1245AC are discordant with those expected from published photocentric-orbit elements. The observed positions of four other multiple systems (Gl 65AB, Gl 244AB, Gl 280AB, and Gl 866ABC) also differ from those expected from published orbital elements. The discrepancies noted for Gl 280AB are sufficient to resolve the long-standing inconsistency between Procyon's observed luminosity and that derived from the theoretical mass-luminosity relation. F1042M images of the astrometric binary Gl 105A do not reveal the presence of a fourth component, as has been proposed to reconcile the differences between the observed location of the M7 V companion Gl 105C and the predicted separations of the perturbing body from two independent astrometric studies.
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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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 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".