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Post Info TOPIC: Trans-Neptunian Binaries


Posts: 131433
RE: Trans-Neptunian Binaries

Title: Discovery and Characterisation of Trans-Neptunian Binaries in Large-Scale Surveys
Authors: Alex H. Parker

The dynamically cold component of the Kuiper Belt is host to a population of very widely separated, near-equal mass binary systems. Such binaries, representing the tail of the separation distribution of the more common, more tightly-bound systems, are known to have on-sky separations up to ~4". Their wide separations make them highly valuable due to their delicacy and sensitivity to perturbation, and also makes them relatively easy targets to characterise from the ground. Parker et al. (2011) present a ground-based characterisation of seven such systems with separations at discovery ranging from 0."5-4", and we will adopt these systems as the prototypes for the ultra-wide binaries of the Kuiper Belt. Here we present the prospects for using future large-scale ground-based optical surveys (with LSST as our baseline survey) to measure the orbital properties of a large sample of these widely separated Trans-Neptunian Binaries (TNBs).

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Posts: 131433
Ultra-Wide Trans-Neptunian Binaries

Title: Collisional Evolution of Ultra-Wide Trans-Neptunian Binaries
Authors:  Alex H. Parker, J. J. Kavelaars

The widely-separated, near-equal mass binaries hosted by the cold Classical Kuiper Belt are delicately bound and subject to disruption by many perturbing processes. We use analytical arguments and numerical simulations to determine their collisional lifetimes given various impactor size distributions, and include the effects of mass-loss and multiple impacts over the lifetime of each system. These collisional lifetimes constrain the population of small (R > ~1 km) objects currently residing in the Kuiper Belt, and confirm that the size distribution slope at small size cannot be excessively steep - likely q < ~3.5. We track mutual semi-major axis, inclination, and eccentricity evolution through our simulations, and show that it is unlikely that the wide binary population represents an evolved tail of the primordially-tight binary population. We find that if the wide binaries are a collisionally-eroded population, their primordial mutual orbit planes must have preferred to lie in the plane of the solar system. Finally, we find that current limits on the size distribution at small radii remain high enough that the prospect of detecting dust-producing collisions in real-time in the Kuiper Belt with future optical surveys is feasible.

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Posts: 131433
Trans-Neptunian Binaries

Title: Characterisation of Seven Ultra-Wide Trans-Neptunian Binaries
Authors: Alex H. Parker, JJ. Kavelaars, Jean-Marc Petit, Lynne Jones, Brett Gladman, Joel Parker

The low-inclination component of the Classical Kuiper Belt is host to a population of extremely widely-separated binaries. These systems are similar to other Trans-Neptunian binaries (TNBs) in that the primary and secondary components of each system are of roughly equal size. We have performed an astrometric monitoring campaign of a sample of seven wide-separation, long-period TNBs and present the first-ever well-characterized mutual orbits for each system. The sample contains the most eccentric (2006 CH69, e=0.9) and the most widely-separated, weakly bound (2001 QW322, a/Rh~0.22) binary minor planets known, and also contains the system with lowest-measured mass of any TNB (2000 CF105, M~1.85E17 kg). Four systems orbit in a prograde sense, and three in a retrograde sense. They have a different mutual inclination distribution compared to all other TNBs, preferring low mutual-inclination orbits. These systems have geometric r-band albedos in the range of 0.09-0.3, consistent with radiometric albedo estimates for larger solitary low-inclination Classical Kuiper Belt objects, and we limit the plausible distribution of albedos in this region of the Kuiper Belt. We find that gravitational collapse binary formation models produce a similar orbital distribution to that currently observed, which along with a confluence of other factors supports formation of the cold Classical Kuiper Belt in situ through relatively rapid gravitational collapse rather than slow hierarchical accretion. We show that these binary systems are sensitive to disruption via collisions, and their existence suggests that the size distribution of TNOs at small sizes remains relatively shallow.

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Trans-Neptunian objects
NameTypeDiameter (km)
(or dimensions)
Name of moonDiameter of moon (km)
(or dimensions)
Separation (km)
134340 PlutoPlutino2306±20Charon (Pluto I)1207±319,571±4
Nix (Pluto II)44-13048,675±120
S/2011 P 1 (Pluto IV)13-3459,000±2,000
Hydra (Pluto III)44-13064,780±90
(26308) 1998 SM165Plutino221?S/2001 (26308) 18811,310 ± 110
42355 TyphonSDO134Echidna (Typhon I)781,300?
(47171) 1999 TC36PlutinoA1=286 +45

A2=265 +41
S/2001 (47171) 1139 +22
7411 ± 12
(48639) 1995 TL8SDO352S/2005 (48639) 1161420
50000 QuaoarCubewano<1100Weywot (Quaoar I)96? ?
(55637) 2002 UX25Cubewano649S/2007 (55637) 1205 ?
58534 LogosCubewano80Zoe (Logos I)668,010 ± 80
(60458) 2000 CM114SDO150?S/2006 (60458) 1119?2,200?
(60621) 2000 FE82:5 resonance151?S/2007 (60621) 1115?1,200
65489 CetoSDO172Phorcys (Ceto I)1341,840
66652 BorasisiCubewano166Pabu (Borasisi I)1374,660 ± 170
(79360) 1997 CS29Cubewano305S/2005 (79360) 12922300
(80806) 2000 CM105Cubewano224S/2005 (80806) 11292700
(82075) 2000 YW134SDO431S/2005 (82075) 12371900
88611 TeharonhiawakoCubewano176 ± 20Sawiskera (Teharonhiawako I)122 ± 1427,300 ± 343
90482 OrcusPlutino946Vanth (Orcus I)262 ± 1708,700
(119979) 2002 WC191:2 resonance420?S/2007 (119979) 1 ? ?
120347 SalaciaCubewano580?Actaea (Salacia I)190?3,500?
(123509) 2000 WK183Cubewano221?S/2007 (123509) 1 ? ?
(134860) 2000 OJ67Cubewano253?S/2003 (134860) 1175?2,300?
136108 HaumeaCubewano1400Hiiaka (Haumea I)31049,500 ± 400
Namaka (Haumea II)17039,300
136199 ErisSDO2,800Dysnomia (Eris I)150-25030,000-36,000
(139775) 2001 QG298Plutino171?S/2004 (139775) 1171?240?
148780 AltjiraCubewano340?S/2007 (148780)

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