Pluto, the Kupier Belt & the Early Compact Solar System

What we Know About Pluto Before the New Horizons Encounter

Where did Pluto's Small Moons Come From?

On the Origin of Pluto's Small Satellites by Resonant Transport

Authors:

Cheng et al

Abstract:

The orbits of Pluto's four small satellites (Styx, Nix, Kerberos, and Hydra) are nearly circular and coplanar with the orbit of the large satellite Charon, with orbital periods nearly in the ratios 3:1, 4:1, 5:1, and 6:1 with Charon's orbital period. These properties suggest that the small satellites were created during the same impact event that placed Charon in orbit and had been pushed to their current positions by being locked in mean-motion resonances with Charon as Charon's orbit was expanded by tidal interactions with Pluto. Using the Pluto-Charon tidal evolution models developed by Cheng et al. (2014), we show that stable capture and transport of a test particle in multiple resonances at the same mean-motion commensurability is possible at the 5:1, 6:1, and 7:1 commensurabilities, if Pluto's zonal harmonic J2P=0. However, the test particle has significant orbital eccentricity at the end of the tidal evolution of Pluto-Charon in almost all cases, and there are no stable captures and transports at the 3:1 and 4:1 commensurabilities. Furthermore, a non-zero hydrostatic value of J2P destroys the conditions necessary for multiple resonance migration. Simulations with finite but minimal masses of Nix and Hydra also fail to yield any survivors. We conclude that the placing of the small satellites at their current orbital positions by resonant transport is extremely unlikely.

Do Orcus and Quaoar Have Liquid Cores?

Conditions for liquid or icy core existence in KBO objects: numerical simulations for Orcus and Quaoar

Authors:

Shchuko et al

Abstract:

In this article, we present a model describing the thermal evolution and structure of Kuiper Belt objects (KBO) as a function of the intensity of radiogenic heat sources, mean density and the object's formation time. We have studied numerically the dependence of the interior composition and structure of a forming body on the accretion rate and radionuclide content in the dust particles, as well as the impact of the radiogenic heat generation rate on the water phase transition dynamics. The model is applied to predict the present internal structure of Plutino (90482) Orcus and KBO (50000) Quaoar with special emphasis on the possibility of cryovolcanism.

Mike Brown: Something's Weird With Kupier Object 2002 UX25

[Mike Brown] gave a presentation of these results at the 2013 meeting of the Division for Planetary Sciences of the American Astronomical Society in October. At this point in the talk I stopped and had the ~100 people in the audience guess what the density of 2002 UX25 was going to be. I gave them the option of (1) lower than water ice like the small objects (2) midway between the small and large objects (3) very rocky like the big objects. The votes were nearly evenly split. Evenly split! Often a group of experts kind of knows what the answer is going to be before you give it. Here no one really had a clue. Including me, I must say. Though, for the record, I voted (2). What’s your vote?

And the answer is….. (1). The Kuiper belt object 2002 UX25 has a density smaller than that of water ice. In fact, 2002 UX25 is the largest solid object in the solar system which could float in water. If you could find a big enough body of water to float it in. As I explained to the audience at the time, this is such a startling result that everyone should currently be gasping.

This answer begs an important question: WHAT IS GOING ON????

link.

New Observations of Quaoar

THE SIZE, SHAPE, ALBEDO, DENSITY, AND ATMOSPHERIC LIMIT OF TRANSNEPTUNIAN OBJECT (50000) QUAOAR FROM MULTI-CHORD STELLAR OCCULTATIONS

Authors:

1. F. Braga-Ribas (a,b,bb)
2. B. Sicardy (b,c)
3. J. L. Ortiz (d)
4. E. Lellouch (b)
5. G. Tancredi (e)
6. J. Lecacheux (b)
7. R. Vieira-Martins (a,f,g)
8. J. I. B. Camargo (a)
9. M. Assafin (g)
10. R. Behrend (h)
11. F. Vachier (f)
12. F. Colas (f)
13. N. Morales (d)
14. A. Maury (i)
15. M. Emilio (j)
16. A. Amorim (k)
17. E. Unda-Sanzana (l)
18. S. Roland (e)
19. S. Bruzzone (e)
20. L. A. Almeida (m)
21. C. V. Rodrigues (m)
22. C. Jacques (n)
23. R. Gil-Hutton (o)
24. L. Vanzi (p)
25. A. C. Milone (m)
26. W. Schoenell (d,k)
27. R. Salvo (e)
28. L. Almenares (e)
29. E. Jehin1 (g)
30. J. Manfroid (q)
31. S. Sposetti (r)
32. P. Tanga1 (i)
33. A. Klotz (t)
34. E. Frappa (u)
35. P. Cacella (u)
36. J. P. Colque (l)
37. C. Neves (j)
38. E. M. Alvarez (v)
39. M. Gillon (q)
40. E. Pimentel (n)
41. B. Giacchini (n)
42. F. Roques (b)
43. T. Widemann (b)
44. V. S. Magalhães (m)
45. A. Thirouin (d)
46. R. Duffard (d)
47. R. Leiva1 (f)
48. I. Toledo (x)
49. J. Capeche (e)
50. W. Beisker (y)
51. J. Pollock (z)
52. C. E. Cedeño Montaña (m)
53. K. Ivarsen (aa)
54. D. Reichart (aa)
55. J. Haislip (aa)
56. A. Lacluyze (aa)

Affiliations:

a. Observatório Nacional, Rio de Janeiro, Brazil

b. Observatoire de Paris, LESIA, F-92195 Meudon, France

c. Université Pierre et Marie Curie, F-75252 Paris, France

d. Instituto de Astrofísica de Andalucía-CSIC, E-18080 Granada, Spain

e. Observatorio Astronomico Los Molinos, Montevideo U-12400, Uruguay

f. Observatoire de Paris, IMCCE, F-75014 Paris, France

g. Observatório do Valongo/UFRJ, Rio de Janeiro, Brazil

h. Observatoire de Genève, Sauverny, Switzerland

i. San Pedro de Atacama Celestial Explorations, San Pedro de Atacama, Chile

j. Universidade Estadual de Ponta Grossa, Ponta Grossa, Brazil

k. Universidade Federal de Santa Catarina, Florianópolis, Brazil

l. Unidad de Astronomía, Universidad de Antofagasta, Antofagasta, Chile

m. Instituto Nacional de Pesquisas Espaciais, DAS, São José dos Campos, Brazil

n. Centro de Estudos Astronômicos de Minas Gerais (CEAMIG), Belo Horizonte, Brazil

o. Complejo Astronómico El Leoncito and San Juan National University, San Juan, Argentina

p. Department of Electrical Engineering and Center of Astro-Engineering, Pontificia Universidad Católica de Chile, Av. Vicuña Mackenna 4860, Santiago, Chile

q. Institut d'Astrophysique de l'Université de Liége, B-4000 Liège, Belgium

r. Gnosca Observatory, Gnosca, Switzerland

s. Laboratoire Lagrange, Université de Sophia Antipolis, Observatoire de la Côte d'Azur, CNRS UMS7293, F-06304 NICE Cedex 4, France

t. Université de Toulouse, UPS-OMP, IRAP, F-31000 Toulouse, France

u. Euraster, 1B cours J. Bouchard, F-42000 St-Etienne, France

v. Rede de Astronomia Observacional, Brasilia, Brazil

w. Observatorio Los Algarrobos, Salto, Uruguay

x. Joint ALMA Observatory, Alonso de Córdova 3107, Vitacura, Santiago, Chile

y. International Occultation Timing Association-European Section, D-30459 Hannover, Germany

z. Department of Physics and Astronomy, Appalachian State University, Boone, NC 28608, USA

aa. Physics and Astronomy Department, University of North Carolina, Chapel Hill, NC, USA

bb. Current address: Rua General José Cristino, 77, CEP 20921-400, Rio de Janeiro, RJ, Brazil.

Abstract:

We present results derived from the first multi-chord stellar occultations by the transneptunian object (50000) Quaoar, observed on 2011 May 4 and 2012 February 17, and from a single-chord occultation observed on 2012 October 15. If the timing of the five chords obtained in 2011 were correct, then Quaoar would possess topographic features (crater or mountain) that would be too large for a body of this mass. An alternative model consists in applying time shifts to some chords to account for possible timing errors. Satisfactory elliptical fits to the chords are then possible, yielding an equivalent radius R equiv = 555 ± 2.5 km and geometric visual albedo pV = 0.109 ± 0.007. Assuming that Quaoar is a Maclaurin spheroid with an indeterminate polar aspect angle, we derive a true oblateness of $\epsilon = 0.087^{+0.0268}_{-0.0175}$, an equatorial radius of $569^{+24}_{-17}$ km, and a density of 1.99 ± 0.46 g cm–3. The orientation of our preferred solution in the plane of the sky implies that Quaoar's satellite Weywot cannot have an equatorial orbit. Finally, we detect no global atmosphere around Quaoar, considering a pressure upper limit of about 20 nbar for a pure methane atmosphere.

In the future, with this many authors, I am not going to reformat.  Good grief.