There were 3 new TNO discoveries announced since the previous issue of Distant EKOs:
2011 HJ103, 2012 HZ84, 2012 XR157
and 10 new Centaur/SDO discoveries:
2011 HK103, 2012 VP113, 2013 FY27, 2013 FZ27, 2013 LU35, 2014 DT112, 2014 FW, 2014 FX43, 2014 GE45, 2014 HY123
Reclassified objects:
2010 GF65 (SDOCentaur)
2012 GX17 (Centaur
2014 FW (Centaur
2013 FZ27 (SDO
Objects recently assigned numbers:
2011 WU92 = (389820)
Objects recently assigned names:
2003 QW111 = Manwe
Current number of TNOs: 1263 (including Pluto)
Current number of Centaurs/SDOs: 393
Current number of Neptune Trojans: 9
Out of a total of 1665 objects:
644 have measurements from only one opposition
631 of those have had no measurements for more than a year
326 of those have arcs shorter than 10 days
(for more details, see:
http://www.boulder.swri.edu/ekonews/objects/recov_stats.jpg)
`ohoku Place, Hilo, HI 96720, USA
The observable Solar System can be divided into three distinct regions: the rocky terrestrial planets including the asteroids at 0.39 to 4.2 astronomical units (AU) from the Sun (where 1 AU is the mean distance between Earth and the Sun), the gas giant planets at 5 to 30 AU from the Sun, and the icy Kuiper belt objects at 30 to 50 AU from the Sun. The 1,000-kilometre-diameter dwarf planet Sedna was discovered ten years ago and was unique in that its closest approach to the Sun (perihelion) is 76 AU, far greater than that of any other Solar System body. Formation models indicate that Sedna could be a link between the Kuiper belt objects and the hypothesized outer Oort cloud at around 10,000 AU from the Sun. Here we report the presence of a second Sedna-like object, 2012 VP113, whose perihelion is 80 AU. The detection of 2012 VP113 confirms that Sedna is not an isolated object; instead, both bodies may be members of the inner Oort cloud, whose objects could outnumber all other dynamically stable populations in the Solar System.
Published in: Nature 507, 471 (2014 March 27)
For preprints, contact trujillo@gemini.edu
The small satellites of the Pluto system (Styx, Nix, Kerberos, and Hydra) have very low surface escape velocities, and impacts should therefore eject a large amount of material from their surfaces. We show that most of this material then escapes from the Pluto system, though a significant fraction collects on the surfaces of Pluto and Charon. The velocity at which the dust is ejected from the surfaces of the small satellites strongly determines which object it is likely to hit, and where on the surfaces of Pluto and Charon it is most likely to impact. We also show that the presence of an atmosphere around Pluto eliminates most particle size effects and increases the number of dust impacts on Pluto. In total, Pluto and Charon may have accumulated several centimeters of small-satellite dust on their surfaces, which could be observed by the New Horizons spacecraft.
Published in: Icarus (Pluto special issue)
Preprints available on the web at
http://arxiv.org/abs/1403.4873
,
F. Roig1,
D.E. Reichart34,
A.P. LaCluyze34,
J.B. Haislip34,
K.M. Ivarsen34,
J.P. Moore34,
N.R. Frank34, and
D.G. Lambas14,30
Royal Society University Research Fellow
Hitherto, rings have been found exclusively around the four giant
planets in the Solar System. Rings are natural laboratories in which to
study dynamical processes analogous to those that take place during the
formation of planetary systems and galaxies. Their presence also tells
us about the origin and evolution of the body they encircle. Here we
report observations of a multichord stellar occultation that revealed
the presence of a ring system around (10199) Chariklo, which is a
Centaur -- that is, one of a class of small objects orbiting primarily
between Jupiter and Neptune -- with an equivalent radius of 124
9 km.
There are two dense rings, with respective widths of about 7
and 3 km, optical depths of 0.4 and 0.06, and orbital radii of
391 and 405 km. The present orientation of the ring is
consistent with an edge-on geometry in 2008, which provides a simple
explanation for the dimming of the Chariklo system between 1997 and
2008, and for the gradual disappearance of ice and other absorption
features in its spectrum over the same period. This implies that the
rings are partly composed of water ice. They may be the remnants of a
debris disk, possibly confined by embedded, kilometre-sized satellites.
This paper contains Supplementary Information.
Published in: Nature, 508, 72 (2014 April 3)
For preprints, contact ribas@on.br
or on the web at http://www.nature.com/nature/journal/v508/n7494/full/nature13155.html
High-resolution spectra of Pluto in the 1.66 
m region, recorded
with the VLT/CRIRES instrument in 2008 (2 spectra) and 2012 (5 spectra),
are analyzed to constrain the spatial and vertical distribution of
methane in Pluto's atmosphere and to search for mid-term (4 year)
variability. A sensitivity study to model assumptions (temperature
structure, surface pressure, Pluto's radius) is performed. Results
indicate that (i) no variation of the CH4 atmospheric content
(column-density or mixing ratio) with Pluto rotational phase is present
in excess of 20% (ii) CH4 column densities show at most marginal
variations between 2008 and 2012, with a best guess estimate of a 
20%
decrease over this time frame. As stellar occultations indicate that
Pluto's surface pressure has continued to increase over this period,
this implies a concomitant decrease of the methane mixing ratio (iii)
the data do not show evidence for an altitude-varying methane
distribution; in particular, they imply a roughly uniform mixing ratio
in at least the first 22-27 km of the atmosphere, and high
concentrations of low-temperature methane near the surface can be ruled
out. Our results are also best consistent with a relatively large
(>1180 km) Pluto radius. Comparison with predictions from a recently
developed global climate model indicates that these features are best
explained if the source of methane occurs in regional-scale CH4 ice
deposits, including both low latitudes and high Northern latitudes,
evidence for which is present from the rotational and secular evolution
of the near-IR features due to CH4 ice. Our ``best guess'' predictions
for the New Horizons encounter in 2015 are: a 1184 km radius, a 17 bar
surface pressure, and a 0.44% CH4 mixing ratio with
negligible longitudinal variations.
To appear in: Icarus (Pluto special issue)
Preprints available on the web at
http://arxiv.org/abs/1403.3208
Combining stellar occultation observations probing Pluto's atmosphere from 1988 to 2013, and models of energy balance between Pluto's surface and atmosphere, we find the preferred models are consistent with Pluto retaining a collisional atmosphere throughout its 248-year orbit. The occultation results show an increasing atmospheric pressure with time in the current epoch, a trend present only in models with a high thermal inertia and a permanent N2 ice cap at Pluto's north rotational pole.
To appear in: Icarus
For preprints, contact colkin@boulder.swri.edu
or on the web at http://arxiv.org/abs/1309.0841
Debris disks are thought to be sculptured by neighboring planets.
The same is true for the Edgeworth-Kuiper debris disk, yet no direct observational
evidence for signatures of giant planets in the Kuiper belt dust distribution has been
found so far.
Here we model the dust distribution in the outer solar system
to reproduce the dust impact rates onto the dust detector onboard the New
Horizons spacecraft measured so far and to predict the rates during the Neptune
orbit traverse.
To this end, we take a realistic distribution of transneptunian
objects to launch a sufficient
number of dust grains of different sizes and follow their orbits by
including radiation pressure, Poynting-Robertson and stellar wind drag,
as well as the perturbations of four giant planets.
In a subsequent statistical analysis, we calculate number densities and lifetimes of
the dust grains in order to simulate a collisional cascade.
In contrast to the previous work, our model not only considers
collisional elimination of particles, but also includes production of finer debris.
We find that particles captured in the 3:2 resonance with Neptune build
clumps that are not removed by collisions, because the depleting effect of collisions is counteracted by production of
smaller fragments.
Our model successfully reproduces the dust impact rates measured by New Horizons
out to 
AU and predicts an increase of the impact rate of about a factor of
two or three around the Neptune orbit crossing.
This result is robust with respect to the variation of the vaguely known
number of dust-producing scattered disk objects,
collisional outcomes, and the dust properties.
To appear in: The Astronomical Journal
For preprints, contact vitense@astro.uni-jena.de
A new Hubble Space Telescope observation of the 7:4 resonant
transneptunian binary system (385446) Manwë has shown that, of
two previously reported solutions for the orbit of its satellite
Thorondor, the prograde one is correct. The orbit has a period of
110.180.02 days, semimajor axis of 667040 km, and an
eccentricity of 0.5630.007. It will be viewable edge-on from
the inner solar system during 2015-2017, presenting opportunities to
observe mutual occultation and eclipse events. However, the number of
observable events will be small, owing to the long orbital period and
expected small sizes of the bodies relative to their separation. This
paper presents predictions for events observable from Earth-based
telescopes and discusses the associated uncertainties and challenges.
To appear in: Icarus
Preprints available at
http://www2.lowell.edu/users/grundy/abstracts/2014.Manwe-Thorondor.html
We combine long-term photometric observations in multiple band passes to
determine the rotational light curve for the binary Kuiper-Belt object
(79360) Sila-Nunam. We measure an unambiguous fundamental period of
d, within 0.02% of half the orbital period (
d) determined earlier from HST observations resolving
the binary. The light curve is double-peaked, and well fit by the sum of
two sinusoids: a primary with period Porb / 2 and peak-to-peak amplitude
mag and a secondary with period Porb and peak- to-peak
amplitude
mag. Excluding observations within 0.1 deg of
opposition, we measure a linear solar phase dependence with slope
mag deg-1 and a mean absolute magnitude in the Gunn g band of
mag. There is no rotational color variation exceeding 4%.
We also observe that eclipses occur centered on light curve minima to
within 0.3%, requiring the long axis of at least one of the two bodies
to point precisely toward the other. Assuming the binary is doubly
synchronous and both rotation axes are aligned with the orbital angular
momentum vector, our observations jointly constrain triaxial shape
models for Sila and Nunam such that the product of their
long-to-intermediate axes ratios is
. Hence both bodies are
elongated by 6%, or else one is elongated by 6% to 12%, and the other
by less than 6%.
To appear in: Icarus
Preprints available on the web at http://arxiv.org/abs/1404.0244
The Kuiper belt is formed of planetesimals which failed to grow to
planets and its dynamical structure has been affected by Neptune. The
classical Kuiper belt contains objects both from a low-inclination,
presumably primordial, distribution and from a high-inclination
dynamically excited population. Based on a sample of classical TNOs with
observations at thermal wavelengths we determine radiometric sizes,
geometric albedos and thermal beaming factors for each object as well as
study sample properties of dynamically hot and cold classicals.
Observations near the thermal peak of TNOs using infra-red space
telescopes are combined with optical magnitudes using the radiometric
technique with near-Earth asteroid thermal model (NEATM). We have
determined three-band flux densities from Herschel/PACS
observations at 70.0, 100.0 and 160.0 m and
Spitzer/MIPS at 23.68 and 71.42 m when available.
We use reexamined absolute visual magnitudes from the literature and
ground based programs in support of Herschel observations. We
have analysed 18 classical TNOs with previously unpublished data and
re-analysed previously published targets with updated data reduction to
determine their sizes and geometric albedos as well as beaming factors
when data quality allows. We have combined these samples with classical
TNOs with radiometric results in the literature for the analysis of
sample properties of a total of 44 objects. We find a median geometric
albedo for cold classical TNOs of
0.14-0.07+0.09 and for
dynamically hot classical TNOs, excluding the Haumea family and dwarf
planets,
0.085-0.045+0.084. We have determined the bulk
densities of Borasisi-Pabu (
2.1-1.2+2.6 g cm-3),
Varda-Ilmarë (
1.25-0.43+0.40 g cm-3) and 2001 QC298
(
1.14-0.30+0.34 g cm-3) as well as updated previous density
estimates of four targets. We have determined the slope parameter of the
debiased cumulative size distribution of dynamically hot classical TNOs
as 
in the diameter range 100 < D < 500 km. For
dynamically cold classical TNOs we determine 
in the
diameter range 160<D<280 km as the cold classical TNOs have a
smaller maximum size.
Published in: Astronomy and Astrophysics, 564, A35
For preprints, contact vilenius@mpe.mpg.de
or on the web at http://arxiv.org/abs/1403.6309
Planet X Revamped after the Discovery of the Sedna-like Object 2012 VP
?
L. Iorio1
1 Ministero dell'Istruzione, dell'Università e della Ricerca (M.I.U. R.). Permanent address for correspondence: Viale Unità di Italia 68, 70125, Bari (BA), Italy
Preprints available on the web at http://arxiv.org/abs/1404.0258
The Secular Evolution of the Kuiper Belt after a Close Stellar Encounter
D. Punzo1, 2, R. Capuzzo-Dolcetta1, and S. Portegies Zwart3
1 Dep. of Physics, Sapienza, University of Roma, P.le A. Moro
1, Roma, Italy
2 Kapteyn Institute, Rijksuniversiteit, Landleven 12, 9747AD
Groningen, Netherlands
3 Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden, The Netherlands
Submitted to: Monthly Notices of the Royal Astronomical Society
Preprint available on the web at http://arxiv.org/abs/1403.6633
WFIRST Ultra-Precise Astrometry I: Kuiper Belt Objects
Andrew Gould1
1 Department of Astronomy, Ohio State University, Colubmus, OH, USA
Submitted to: The Astrophysical Journal
Preprints available on the web at http://arxiv.org/abs/1403.4241
Uranus has three known co-orbitals: 83982 Crantor (2002 GO9), 2010 EU65 and 2011 QF99. All of them were captured in their current resonant state relatively recently. Here, we perform a comparative analysis of the orbital evolution of these transient co-orbitals to understand better how they got captured in the first place and what makes them dynamically unstable. We also look for additional temporary Uranian co-orbital candidates among known objects. Our N-body simulations show that the long-term stability of 2011 QF99 is controlled by Jupiter and Neptune; it briefly enters the 1:7 mean motion resonance with Jupiter and the 2:1 with Neptune before becoming a Trojan and prior to leaving its tadpole orbit. During these ephemeral two-body mean motion resonance episodes, apsidal corotation resonances are also observed. For known co-orbitals, Saturn is the current source of the main destabilizing force but this is not enough to eject a minor body from the 1:1 commensurability with Uranus. These objects must enter mean motion resonances with Jupiter and Neptune in order to be captured or become passing Centaurs. Asteroid 2010 EU65, a probable visitor from the Oort cloud, may have been stable for several Myr due to its comparatively low eccentricity. Additionally, we propose 2002 VG131 as the first transient quasi-satellite candidate of Uranus. Asteroid 1999 HD12 may signal the edge of Uranus' co-orbital region. Transient Uranian co-orbitals are often submitted to complex multi-body ephemeral mean motion resonances that trigger the switching between resonant co-orbital states, making them dynamically unstable. In addition, we show that the orbital properties and discovery circumstances of known objects can be used to outline a practical strategy by which additional Uranus' co-orbitals may be found.
To appear in: Monthly Notices of the Royal Astronomical Society
For preprints, contact nbplanet@fis.ucm.es
or on the web at http://arxiv.org/abs/1404.2898
http://sbd14.sciencesconf.org
The Small Bodies Dynamics (SBD) meeting intends to provide a new space for in-depth and stimulating discussions and talks on all aspects of minor bodies dynamics. Topics covered by this meeting will involve the dynamical evolution of asteroids, TNOs, satellites, rings, dust, and space probes. The SBD meeting will feature invited talks on a range of topics, contributed talks, and posters.
The meeting will take place in the Hotel Wembly Inn, in Ubatuba, SP, Brazil,
on August 24-28th. More information on the conference is available at:
http://sbd14.sciencesconf.org
We accept submissions for the following sections:
Distant EKOs is not a refereed publication, but is a tool for furthering communication among people interested in Kuiper belt research. Publication or listing of an article in the Newsletter or the web page does not constitute an endorsement of the article's results or imply validity of its contents. When referencing an article, please reference the original source; Distant EKOs is not a substitute for peer-reviewed journals.