The Young L Dwarf 2MASS J11193254−1137466 Is a Planetary-mass Binary
Bibliographic record
Abstract
Abstract We have discovered that the extremely red, low-gravity L7 dwarf 2MASS J11193254−1137466 is a 0.″14 (3.6 au) binary using Keck laser guide star adaptive optics imaging. 2MASS J11193254−1137466 has previously been identified as a likely member of the TW Hydrae Association (TWA). Using our updated photometric distance and proper motion, a kinematic analysis based on the BANYAN II model gives an 82% probability of TWA membership. At TWA’s 10 ± 3 Myr age and using hot-start evolutionary models, 2MASS J11193254−1137466AB is a pair of brown dwarfs, making it the lowest-mass binary discovered to date. We estimate an orbital period of years. One component is marginally brighter in K band but fainter in J band, making this a probable flux-reversal binary, the first discovered with such a young age. We also imaged the spectrally similar TWA L7 dwarf WISEA J114724.10−204021.3 with Keck and found no sign of binarity. Our evolutionary model-derived estimate for WISEA J114724.10−204021.3 is ≈230 K higher than for 2MASS J11193254−1137466AB, at odds with the spectral similarity of the two objects. This discrepancy suggests that WISEA J114724.10−204021.3 may actually be a tight binary with masses and temperatures very similar to 2MASS J11193254−1137466AB, or further supporting the idea that near-infrared spectra of young ultracool dwarfs are shaped by factors other than temperature and gravity. 2MASS J11193254−1137466AB will be an essential benchmark for testing evolutionary and atmospheric models in the young planetary-mass regime.
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How this classification was reachedexpand
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 | 0.004 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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 itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, 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".