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TOPIC: (136108) 2003EL61


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Dwarf Planet (136108) Haumea
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The Dwarf Planet (136108) Haumea is at Opposition (49.617 AU) on the 15th April 2018



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RE: (136108) 2003EL61
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Dwarf Planet (136108) Haumea (2003 EL61) is at Opposition (49.831 AU) in the constellation Bootes on the 12th April 2015



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Dwarf Planet 136108 Haumea
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Dwarf Planet (136108) Haumea is at Opposition (49.895 AU) on the 10th April 2014



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RE: (136108) 2003EL61
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Title: The size and shape of the oblong dwarf planet Haumea
Author: Alexandra C. Lockwood, Michael E. Brown, John Stansberry

We use thermal radiometry and visible photometry to constrain the size, shape, and albedo of the large Kuiper belt object Haumea. The correlation between the visible and thermal photometry demonstrates that Haumea's high amplitude and quickly varying optical light curve is indeed due to Haumea's extreme shape, rather than large scale albedo variations. However, the well-sampled high precision visible data we present does require longitudinal surface heterogeneity to account for the shape of lightcurve. The thermal emission from Haumea is consistent with the expected Jacobi ellipsoid shape of a rapidly rotating body in hydrostatic equilibrium. The best Jacobi ellipsoid fit to the visible photometry implies a triaxial ellipsoid with axes of length 1920 x 1540 x 990 km and density 2.6 g cm^-3, as found by Lellouch et al(2010). While the thermal and visible data cannot uniquely constrain the full non-spherical shape of Haumea, the match between the predicted and measured thermal flux for a dense Jacobi ellipsoid suggests that Haumea is indeed one of the densest objects in the Kuiper belt.

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Dwarf Planet 136108 Haumea is at Opposition (49.956 AU) on the 9th April, 2013.



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Date:
Dwarf Planet (136108) Haumea
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Dwarf Planet (136108) Haumea is at Opposition (50.0136 AU) on the 7th, April, 2012.



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RE: (136108) 2003EL61
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Dwarf Planet (136108) Haumea is Stationary on the 29th January, 2012.



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Dwarf planet (136108) Haumea
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Dwarf planet (136108) Haumea is at Quadrature on the 17th January, 2012.



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Haumea's collisional family
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Title: The dynamical evolution of dwarf planet (136108) Haumea's collisional family: General properties and implications for the trans-Neptunian belt
Authors: Patryk Sofia Lykawka, Jonathan Horner, Tadashi Mukai, Akiko M. Nakamura

Recently, the first collisional family was identified in the trans-Neptunian belt. The family consists of Haumea and at least ten other ~100km-sized trans-Neptunian objects (TNOs) located in the region a = 42 - 44.5 AU. In this work, we model the long-term orbital evolution of an ensemble of fragments representing hypothetical post-collision distributions at the time of the family's birth. We consider three distinct scenarios, in which the kinetic energy of dispersed particles were varied such that their mean ejection velocities (veje) were of order 200 m/s, 300 m/s and 400 m/s, respectively. Each simulation considered resulted in collisional families that reproduced that currently observed. The results suggest that 60-75% of the fragments created in the collision will remain in the trans-Neptunian belt, even after 4 Gyr of dynamical evolution. The surviving particles were typically concentrated in wide regions of orbital element space centred on the initial impact location, with their orbits spread across a region spanning {\Delta}a ~ 6-12 AU, {\Delta}e ~ 0.1-0.15 and {\Delta}i ~ 7-10{\deg}. Most of the survivors populated the so-called Classical and Detached regions of the trans-Neptunian belt, whilst a minor fraction entered the Scattered Disk reservoir (<1%), or were captured in Neptunian mean motion resonances (<10%). In addition, except for those fragments located near strong resonances, the great majority displayed negligible long-term orbital variation. This implies that the orbital distribution of the intrinsic Haumean family can be used to constrain the orbital conditions and physical nature of the collision that created the family, billions of years ago. Indeed, our results suggest that the formation of the Haumean collisional family most likely occurred after the bulk of Neptune's migration was complete, or even some time after the migration had completely ceased.

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Haumea
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Title: Rotational fission of Trans-Neptunian Objects. The case of Haumea
Authors: J.L. Ortiz, A. Thirouin, A. Campo Bagatin, R. Duffard, J. Licandro, D.C. Richardson, P. Santos-Sanz, N. Morales, P.G. Benavidez

We present several lines of evidence based on different kinds of observations to conclude that rotational fission has likely occurred for a fraction of the known Trans-Neptunian Objects (TNOs). It is also likely that a number of binary systems have formed from that process in the trans-neptunian belt. We show that Haumea is a potential example of an object that has suffered a rotational fission. Its current fast spin would be a slight evolution of a primordial fast spin, rather than the result of a catastrophic collision, because the percentage of objects rotating faster than 4 hours would not be small in a maxwellian distribution of spin rates that fits the current TNO rotation database. On the other hand, the specific total angular momentum of Haumea and its satellites falls close to that of the high size ratio asteroid binaries, which are thought to be the result of rotational fissions or mass shedding. We also present N-body simulations of rotational fissions applied to the case of Haumea, which show that this process is feasible, might have generated satellites, and might have even created a "family" of bodies orbitally associated to Haumea. The orbitally associated bodies may come from the direct ejection of fragments according to our simulations, or through the evolution of a proto-satellite formed during the fission event. Also, the disruption of an escaped fragment after the fission might create the orbitally related bodies. If any of those mechanisms are correct, other rotational fission families may be detectable in the trans-neptunian belt in the future, and perhaps even TNO pairs might be found (pairs of bodies sharing very similar orbital elements, but not bound together).

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