Trans-Neptunian Binaries - Astronomy News

Blobrana

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Posts: 131433

Date: Jul 4 21:17 2012

RE: Trans-Neptunian Binaries	Permalink

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). Read more (17kb, PDF) __________________

Blobrana

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Posts: 131433

Date: Nov 10 13:34 2011

Ultra-Wide Trans-Neptunian Binaries	Permalink

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. Read more (1516kb, PDF) __________________

Blobrana

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Posts: 131433

Date: Aug 15 20:57 2011

Trans-Neptunian Binaries

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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

Name	Type	Diameter (km) (or dimensions)	Name of moon	Diameter of moon (km) (or dimensions)	Separation (km)
134340 Pluto	Plutino	2306±20	Charon (Pluto I)	1207±3	19,571±4
			Nix (Pluto II)	44-130	48,675±120
			S/2011 P 1 (Pluto IV)	13-34	59,000±2,000
			Hydra (Pluto III)	44-130	64,780±90
(26308) 1998 SM₁₆₅	Plutino	221?	S/2001 (26308) 1	88	11,310 ± 110
42355 Typhon	SDO	134	Echidna (Typhon I)	78	1,300?
(47171) 1999 TC₃₆	Plutino	A₁=286 +45 -38 A₂=265 +41 -35	S/2001 (47171) 1	139 +22 -18	7411 ± 12
(48639) 1995 TL₈	SDO	352	S/2005 (48639) 1	161	420
50000 Quaoar	Cubewano	<1100	Weywot (Quaoar I)	96?	?
(55637) 2002 UX₂₅	Cubewano	649	S/2007 (55637) 1	205	?
58534 Logos	Cubewano	80	Zoe (Logos I)	66	8,010 ± 80
(60458) 2000 CM₁₁₄	SDO	150?	S/2006 (60458) 1	119?	2,200?
(60621) 2000 FE₈	2:5 resonance	151?	S/2007 (60621) 1	115?	1,200
65489 Ceto	SDO	172	Phorcys (Ceto I)	134	1,840
66652 Borasisi	Cubewano	166	Pabu (Borasisi I)	137	4,660 ± 170
(79360) 1997 CS₂₉	Cubewano	305	S/2005 (79360) 1	292	2300
(80806) 2000 CM₁₀₅	Cubewano	224	S/2005 (80806) 1	129	2700
(82075) 2000 YW₁₃₄	SDO	431	S/2005 (82075) 1	237	1900
88611 Teharonhiawako	Cubewano	176 ± 20	Sawiskera (Teharonhiawako I)	122 ± 14	27,300 ± 343
90482 Orcus	Plutino	946	Vanth (Orcus I)	262 ± 170	8,700
(119979) 2002 WC₁₉	1:2 resonance	420?	S/2007 (119979) 1	?	?
120347 Salacia	Cubewano	580?	Actaea (Salacia I)	190?	3,500?
(123509) 2000 WK₁₈₃	Cubewano	221?	S/2007 (123509) 1	?	?
(134860) 2000 OJ₆₇	Cubewano	253?	S/2003 (134860) 1	175?	2,300?
136108 Haumea	Cubewano	1400	Hiiaka (Haumea I)	310	49,500 ± 400
136108 Haumea	Cubewano	1400	Namaka (Haumea II)	170	39,300
136199 Eris	SDO	2,800	Dysnomia (Eris I)	150-250	30,000-36,000
(139775) 2001 QG₂₉₈	Plutino	171?	S/2004 (139775) 1	171?	240?
148780 Altjira	Cubewano	340?	S/2007 (148780)

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