OSSOS. VI. Striking Biases in the Detection of Large Semimajor Axis Trans-Neptunian Objects
Open accessAbstract
The accumulating but small set of large semimajor axis trans-Neptunian objects (TNOs) shows an apparent clustering in the orientations of their orbits. This clustering must either be representative of the intrinsic distribution of these TNOs, or else have arisen as a result of observation biases and/or statistically expected variations for such a small set of detected objects. The clustered TNOs were detected across different and independent surveys, which has led to claims that the detections are therefore free of observational bias. This apparent clustering has led to the so-called “Planet 9” hypothesis that a super-Earth currently resides in the distant solar system and causes this clustering. The Outer Solar System Origins Survey (OSSOS) is a large program that ran on the Canada–France–Hawaii Telescope from 2013 to 2017, discovering more than 800 new TNOs. One of the primary design goals of OSSOS was the careful determination of observational biases that would manifest within the detected sample. We demonstrate the striking and non-intuitive biases that exist for the detection of TNOs with large semimajor axes. The eight large semimajor axis OSSOS detections are an independent data set, of comparable size to the conglomerate samples used in previous studies. We conclude that the orbital distribution of the OSSOS sample is consistent with being detected from a uniform underlying angular distribution.
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The OSSOS survey was limited to two regions of ecliptic longitude, and these two longitudes are nearly orthogonal to the apparent longitude of perihelion clustering.
“the survey was limited to two regions of ecliptic longitude, and these two longitudes are nearly orthogonal to the apparent longitude of perihelion clustering.”
From Orbital Clustering in the Distant Solar System (2019) · cites this paper as Shankman et al. 2017
The Discussion and Summary supports restricted spring and fall observing, broadly consistent with two observing regions. But it says OSSOS was primarily sensitive to orbits with longitudes of perihelion near the apparent clustering region, not orthogonal to it. The orthogonal orbit it describes belongs to one detected TNO, o5p060, rather than to the survey’s two observing regions. (LLM, conf=0.85)
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Experimental — accuracy not yet measuredThe OSSOS survey's discovery of 4 objects with semimajor axis beyond 230 AU was consistent with a uniform distribution of orbital angles.
“calculation of the full set of observational biases for the well calibrated OSSOS survey found that their discovery of 4 objects with semimajor axis beyond 230 AU was consistent with a uniform distribution of orbital angles (Shankman et al. 2017)”
From Orbital Clustering in the Distant Solar System (2019) · cites this paper as Shankman et al. 2017
Section 2.1 reports four OSSOS objects with semimajor axes greater than 250 AU, not the claim’s 230 AU cutoff. Section 3.2 finds that the orbital angles of those four objects are statistically consistent with uniform intrinsic distributions after accounting for survey bias. Our copy does not establish that exactly four objects exceeded 230 AU. Page numbers are unavailable in the indexed passages. (LLM, conf=0.88)
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“…the well calibrated OSSOS survey found that their discovery of 4 objects with semimajor axis beyond 230 AU was consistent with a uniform distribution of or- mbrown@caltech.edu, kbatygin@gps.caltech.edu bital angles (Shankman et al. 2017), in apparent conflict with the clustering observed elsewhere.”
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No Evidence for Orbital Clustering in the Extreme Trans-Neptunian Objects
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- Authors
- Shankman, C., Kavelaars, J. J., Bannister, M. T., Gladman, B. J., Lawler, S. M., Chen 陳英, Y.-T. 同., Jakubik, M., Kaib, N., Alexandersen, M., Gwyn, S. D. J., Petit, J.-M., & Volk, K.
- Affiliations
- University of Victoria (CA)
- Herzberg Institute of Astrophysics (CA)
- Queen's University Belfast (GB)
- University of British Columbia (CA)
- University of Oklahoma (US)
- Institute of Astronomy and Astrophysics, Academia Sinica (TW)
- Centre National de la Recherche Scientifique (FR)
- University of Arizona (US)
- ORCID
- Venue
- The Astronomical Journal
- Publisher
- American Astronomical Society
- Published
- 2017-07-14
- Volume
- 154
- Issue
- 2
- Pages
- 50
- ISSN
- 0004-6256 (ISSN-L)
- 1538-3881
- OpenAlex
- W2625988104
- Semantic Scholar
- 2d265184647c114e2c7076e2258af5f4eed2ec62
- Cited by
- 87
- References
- 29
- Citations by year
- 2026: 3 · 2025: 7 · 2024: 7 · 2023: 7 · 2022: 8 · 2021: 13 · 2020: 15 · 2019: 10 · 2018: 11 · 2017: 6
- FWCI
- 6.28
- Type
- journal article
- Language
- en
- Open access
- bronze
- doi.org
- Licence
- Locations
- The Astronomical Journal (publishedVersion)
- UA Campus Repository (The University of Arizona) (acceptedVersion)
- arXiv (Cornell University) (submittedVersion)
- HAL (submittedVersion, cc-by)
- NPARC (submittedVersion)
- Research Portal (Queen's University Belfast) (submittedVersion, other-oa)
- arXiv (Cornell University)
- Funders
- Academia Sinica
- Centre National de la Recherche Scientifique
- Canadian Space Agency
- Natural Sciences and Engineering Research Council of Canada
- Science and Technology Facilities Council (ST/L000709/1, L000709/1)
- Topics
- Physical Sciences › Physics and Astronomy › Astronomy and Astrophysics › Astro and Planetary Science
- Physical Sciences › Physics and Astronomy › Astronomy and Astrophysics › Stellar, planetary, and galactic studies
- Physical Sciences › Engineering › Aerospace Engineering › Space Satellite Systems and Control
- Keywords
- trans-Neptunian objects, observation bias, orbital clustering, orbital distribution
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