Phase Curves from the Kuiper Belt: Photometric Properties of Distant Kuiper Belt Objects Observed by New Horizons
Bibliographic record
Abstract
Abstract Prior to its close encounter with the Kuiper Belt object (KBO) (486958) 2014 MU69 on 2019 January 1, NASA’s New Horizons spacecraft observed other KBOs from distances greater than 0.1 au at solar phase angles far larger than those attainable from Earth. The expanded range in phase angle afforded by these distant KBO (DKBO) observations enables comparisons between their phase functions and those of other solar system objects. Here we present extended New Horizons phase angle coverage of plutino (15810) Arawn (1994 JR1) to 131°, resonant KBO 2012 HE85 to 64°, scattered disk KBO 2011 HK103 to 124°, hot classical (515977) 2012 HZ84 to 73°, and cold classical KBOs 2011 HJ103 and 2011 JY31 to 27° and 122°, respectively. In general, DKBO solar phase curves have slopes (i.e., phase coefficients) and shapes (with corresponding phase integrals q) similar to those of other dark, small solar system objects including comet nuclei, asteroids, and satellites. Until stellar occultations by these DKBOs provide information about their size, geometric albedos p (and Bond albedos A = pq) must be inferred from the median albedos measured by thermal radiometry for each dynamical class. Bond albedos for these DKBOs range from 0.01 to 0.04. Cold classical JY31 has a slightly lower slope and higher phase integral than the other DKBOs, and its slope and phase integral come closest to matching those of cold classical MU69, suggesting that cold classical KBOs share surface scattering characteristics that are distinct from those of other KBOs.
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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 | 0.000 | 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) | 0.001 | 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 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".