A carefully characterised trans-neptunian survey
department or school: Science, Faculty of
department or school: Physics and Astronomy, Department of
data provider: DSpace
degree campus: UBCV
creator: Alexandersen, Mike
issued: 2015-08-17T14:58:42Z
issued: 2015
related degree: Doctor of Philosophy - PhD
degree grantor: University of British Columbia
description: The Trans-Neptunian objects (TNOs) preserve evidence of planet building processes in their orbital and size distributions. While all populations show steep size distributions for large objects, recently a relative deficit of Neptunian Trojans and scattering objects with diameters D<100 km was detected. We have investigated this deficit with a 32 square degree survey, in which we detected 77 TNOs brighter than a limiting r-band magnitude of 24.6. Our Plutino sample (18 objects in 3:2 mean motion resonance with Neptune) also shows a deficit of D<100 km objects. We reject a single power-law size distribution at >99% confidence. The fact that three independent samples of three different populations show this trend suggests that it is a real feature, possibly shared by all hot TNO populations as a remnant of ''born big'' planetesimal formation processes. We surmise the existence of 9000 ± 3000 Plutinos with absolute magnitude Hr ≤ 8.66 and estimate 37000 +12000/-10000 Plutinos with Hr ≤ 10.0 (95% confidence ranges). Our survey also discovered one temporary Uranian Trojan, one temporary Neptunian Trojan and one stable Neptunian Trojan. With these discoveries, combined with our survey characteristics, we derive populations of 110 +500/-100, 210 +900/-200 and 150 +600/-140 for these populations, respectively, with Hr ≤ 10.0. With such approximately equal numbers, the temporary Neptunian Trojans cannot be previously stable Trojans that happen to be escaping the resonance now; they must be captured from another reservoir. Our population estimate also reveals that the Neptunian Trojans are less numerous than the main belt asteroids (semi-major axis 2.06<a<3.65), which has 592 asteroids with Hr ≤ 10.0. As the bias against detection of objects grows with larger semi-major axis, our discovery of three 3:1 resonators and one 4:1 resonator adds to the growing evidence that the high-order resonances are far more populated than can currently be explained theoretically.
aggregated CHO: https://circle.library.ubc.ca/rest/handle/2429/54455
note: A carefully characterised Trans-NeptuniansurveybyMike AlexandersenB. Astronomy, University of Copenhagen, 2007M. Astronomy, University of Copenhagen, 2009a thesis submitted in partial fulfillmentof the requirements for the degree ofDoctor of Philosophyinthe faculty of graduate and postdoctoralstudies(Astronomy)The University of British Columbia(Vancouver)August 2015c© Mike Alexandersen, 2015AbstractThe Trans-Neptunian Objects (TNOs) preserve evidence of planet buildingprocesses in their orbital and size distributions. While all populations showsteep size distributions for large objects, recently a relative deficit of Neptu-nian Trojans and scattering objects with diametersD < 100 km was detected.We have investigated this deficit with a 32 square degree survey, in which wedetected 77 TNOs brighter than a limiting r-band magnitude of 24.6. OurPlutino sample (18 objects in 3:2 mean motion resonance with Neptune)also shows a deficit of D < 100 km objects. We reject a single power-law sizedistribution at > 99% confidence. The fact that three independent samplesof three different populations show this trend suggests that it is a real fea-ture, possibly shared by all hot TNO populations as a remnant of “born big”planetesimal formation processes. We surmise the existence of 9000 ± 3000Plutinos with absolute magnitude Hr ≤ 8.66 and estimate 37000+12000−10000 Pluti-nos with Hr ≤ 10.0 (95% confidence ranges). Our survey also discovered onetemporary Uranian Trojan, one temporary Neptunian Trojan and one stableNeptunian Trojan. With these discoveries, combined with our survey char-acteristics, we derive populations of 110+500−100, 210+900−200 and 150+600−140 for thesepopulations, respectively, with Hr ≤ 10.0. With such approximately equalnumbers, the temporary Neptunian Trojans cannot be previously stable Tro-jans that happen to be escaping the resonance now; they must be capturedfrom another reservoir. Our population estimate also reveals that the Nep-tunian Trojans are less nu…
has type: Thesis/Dissertation
date issued: 2015-09
is shown at: 10.14288/1.0166545
language: eng
degree discipline: Astronomy
provider: Vancouver : University of British Columbia Library
publisher: University of British Columbia
rights: Attribution-NonCommercial-NoDerivs 2.5 Canada
rights URI: http://creativecommons.org/licenses/by-nc-nd/2.5/ca/
scholar level: Graduate
type: Text
identifier URI: http://hdl.handle.net/2429/54455