There were 7 new TNO discoveries announced since the previous issue of Distant EKOs:
2007 RM283, 2007 RT15, 2007 TC418, 2007 TD418, 2007 TZ417, 2007 VJ302, 2007 VK302
and 4 new Centaur/SDO discoveries:
2007 RG283, 2007 RH283, 2007 TA418, 2007 TB418
Reclassified objects:
2007 RW10 (NTrojanCentaur)
Objects recently assigned numbers:
2000 GE147 = 168700
2000 GP183 = 168703
2001 FR185 = 169071
2003 MW12 = 174567
2004 PF115 = 175113
Current number of TNOs: 1074 (including Pluto)
Current number of Centaurs/SDOs: 213
Current number of Neptune Trojans: 5
Out of a total of 1292 objects:
555 have measurements from only one opposition
540 of those have had no measurements for more than a year
278 of those have arcs shorter than 10 days
(for more details, see:
http://www.boulder.swri.edu/ekonews/objects/recov_stats.gif)
We explore the origin and orbital evolution of the Kuiper belt in the framework of a recent model of the dynamical evolution of the giant planets, sometimes known as the Nice model. This model is characterized by a short, but violent, instability phase, during which the planets were on large eccentricity orbits. It successfully explains, for the first time, the current orbital architecture of the giant planets (Tsiganis et al. 2005, Nature 435, 459), the existence of the Trojans populations of Jupiter and Neptune (Morbidelli et al. 2005, Nature 435, 462), and the origin of the late heavy bombardment of the terrestrial planets (Gomes et al. 2005, Nature 435, 466). One characteristic of this model is that the proto-planetary disk must have been truncated at roughly 30 to 35 AU so that Neptune would stop migrating at its currently observed location. As a result, the Kuiper belt would have initially been empty.
In this paper we present a new dynamical mechanism which can
deliver objects from the region interior to 
AU to the
Kuiper belt without excessive inclination excitation. In particular,
we show that during the phase when Neptune's eccentricity is
large, the region interior to its 1:2 mean motion resonance becomes
unstable and disk particles can diffuse into this area. In
addition, we perform numerical simulations where the planets are
forced to evolve using fictitious analytic forces, in a way
consistent with the direct N-body simulations of the Nice model.
Assuming that the last encounter with Uranus delivered Neptune
onto a low-inclination orbit with a semi-major axis of 
AU
and an eccentricity of 
, and that subsequently Neptune's
eccentricity damped in 
My, our simulations reproduce
the main observed properties of the Kuiper belt at an unprecedented
level. In particular, our results explain, at least qualitatively:
1) the so-existence of resonant and non-resonant populations, 2)
the eccentricity-inclination distribution of the Plutinos, 3)
the peculiar semi-major axis - eccentricity distribution in the
classical belt, 4) the outer edge at the 1:2 mean motion resonance
with Neptune, 5) the bi-modal inclination distribution of the
classical population, 6) the correlations between inclination and
physical properties in the classical Kuiper belt, the existence
of the so-called extended scattered disk. Nevertheless, we observe
in the simulations a deficit of nearly-circular objects in the
classical Kuiper belt.
To appear in: Icarus
For preprints, contact hal@boulder.swri.edu
or on the web at
http://arxiv.org/abs/0712.0553
Trans-Neptunian objects (TNOs) are remnants of a collisionally and dynamically evolved planetesimal disk in the outer solar system. This complex structure, known as the trans-Neptunian belt (or Edgeworth-Kuiper belt), can reveal important clues about disk properties, planet formation, and other evolutionary processes. In contrast to the predictions of accretion theory, TNOs exhibit surprisingly large eccentricities, e, and inclinations, i, which can be grouped into distinct dynamical classes. Several models have addressed the origin and orbital evolution of TNOs, but none have reproduced detailed observations, e.g., all dynamical classes and peculiar objects, or provided insightful predictions. Based on extensive simulations of planetesimal disks with the presence of the four giant planets and massive planetesimals, we propose that the orbital history of an outer planet with tenths of Earth's mass can explain the trans-Neptunian belt orbital structure. This massive body was likely scattered by one of the giant planets, which then stirred the primordial planetesimal disk to the levels observed at 40-50 AU and truncated it at about 48 AU before planet migration. The outer planet later acquired an inclined stable orbit (>100 AU; 20-40 deg) because of a resonant interaction with Neptune (an r:1 or r:2 resonance possibly coupled with the Kozai mechanism), guaranteeing the stability of the trans-Neptunian belt. Our model consistently reproduces the main features of each dynamical class with unprecedented detail; it also satisfies other constraints such as the current small total mass of the trans-Neptunian belt and Neptune's current orbit at 30.1 AU. We also provide observationally testable predictions.
To appear in: The Astronomical Journal
For preprints, contact patryk@dragon.kobe-u.ac.jp
or on the web at
http://harbor.scitec.kobe-u.ac.jp/~patryk/index-en.html
EL61
We present high precision, time-resolved visible and near infrared
photometry of the large (diameter 
2500 km) Kuiper belt object
(136108) 2003EL61. The new data confirm rapid rotation
at period P = 3.9155
0.0001hr with a peak-to-peak photometric
range 
= 0.290.02mag. and further show subtle
but reproducible color variations with rotation. Rotational
deformation of 2003EL61 alone would give rise to a symmetric
lightcurve free of color variations. The observed photometric
deviations from the best-fit equilibrium model show the existence
of a large surface region with an albedo and color different from
the mean surface of 2003EL61. We explore constraints on
the nature of this anomalous region set by the existing data.
To appear in: The Astrophysical Journal
For preprints, contact pedro@ifa.hawaii.edu
or on the web at
http://www.ifa.hawaii.edu/~pedro/papers.html
The aim of this paper is to investigate the surface composition of
the Transneptunian Object (TNO) Orcus. High quality observations
have been carried out with the new instrument SINFONI at the Very
Large Telescope (VLT) of ESO. Crystalline water ice, and possibly
ammonia ice, have been found from spectroscopic observations of the
TNO Orcus between 1.4 and 2.4 
m. The existence of such ices
on the surface of Orcus may indicate a renewal mechanism on the
surface and geological activity. The presence of ammonia on the
surface of Orcus, if confirmed, could have important implications
for the composition of the primitive solar nebula and the formation
of the TNO population.
To appear in:
Astronomy & Astrophysics
For preprints, contact antonella.barucci@obspm.fr
We present high signal precision optical reflectance spectra of
2005 FY9 taken with the Red Channel Spectrograph and the 6.5-m MMT
telescope on 2006 March 4 UT (5000-9500 Å; 6.33 Å pixel-1)
and 2007 February 12 UT (6600-8500 Å; 1.93 Å pixel-1).
From cross correlation experiments between the 2006 March 4 spectrum
and a pure CH4-ice Hapke model, we find the CH4-ice bands in
the MMT spectrum are blueshifted by 34 Å relative to bands
in the pure CH4-ice Hapke spectrum. The higher resolution MMT
spectrum of 2007 February 12 UT enabled us to measure shifts of
individual CH4-ice bands. We find the 7296 Å, 7862 Å, and
7993 Å CH4-ice bands are blueshifted by 42 Å, 44 Å,
and 65 Å. From four measurements we report here and one of
our previously published measurements, we find the CH4-ice bands
are shifted by 41 Å. This small shift is important because
it suggest the presence of another ice component on the surface of
2005 FY9. Laboratory experiments show that CH4-ice bands in
spectra of CH4 mixed with other ices are blueshifted relative
to bands in spectra of pure CH4-ice. A likely candidate for the
other component is N2-ice because its weak 2.15 m band and
blueshifted CH4 bands are seen in spectra of Triton and Pluto.
Assuming the shift is due to the presence of N2, spectra taken
on two consecutive nights show no difference in CH4/N2. In
addition, we find no measurable difference in CH4/N2 at
different depths into the surface of 2005 FY9.
To appear in:
Icarus
For preprints, contact Stephen.Tegler@nau.edu
or on the web at http://arxiv.org/abs/0801.3115
The results of a search for sub-km Kuiper Belt Objects (KBOs) with
the method of serendipitous stellar occultations are reported.
Photometric time series were obtained on the 1.8m telescope at the
Dominion Astrophysical Observatory (DAO) in Victoria, British
Columbia, and were analyzed for the presence of occultation events.
Observations were performed at 40 Hz and included a total of 5.0
star-hours for target stars in the ecliptic open cluster M35
(
), and 2.1 star-hours for control stars in the
off-ecliptic open cluster M34 (
). To evaluate
the recovery fraction of the analysis method, and thereby determine
the limiting detectable size, artificial occultation events were
added to simulated time series (1/f scintillation-like power-spectra),
and to the real data. No viable candidate occultation events were
detected. This limits the cumulative surface density of KBOs to
3.5 x 1010 deg-2 (95% confidence) for KBOs brighter
than mR=35.3 (larger than 860 m in diameter, assuming a
geometric albedo of 0.04 and a distance of 40 AU). An evaluation
of TNO occultations reported in the literature suggests that they
are unlikely to be genuine, and an overall 95%-confidence upper
limit on the surface density of
2.8 x 109 deg-2 is
obtained for KBOs brighter than mR=35 (larger than 1 km
in diameter, assuming a geometric albedo of 0.04 and a distance of
40 AU) when all existing surveys are combined.
To appear in:
The Astronomical Journal
For preprints, contact bick@astro.princeton.edu
or on the web at http://arXiv.org/abs/0801.2969
A 2-3 decade mission is proposed with a solar-sail spacecraft approaching the Sun within 0.2 AU. After sail unfurlment at the perihelion of an initially elliptical solar orbit and the completion of acceleration, the spacecraft splits into two components. One part is a scientific payload bound for the heliopause; the second is designed to rendezvous with a Kuiper Belt Object and decelerates across the solar system using Radioisotope-Electric Propulsion.
Published in: Journal of the British Interplanetary Society, 60, 439 (2007 Dec)
For preprints, contact GMatloff@citytech.cuny.edu
Masses of Nix and Hydra
David J. Tholen1, Marc W. Buie2, William M. Grundy2, and Garrett T. Elliott3
1 Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822, USA
2 Lowell Observatory, 1400 W. Mars Hill Road, Flagstaff, AZ 86001, USA
3 The Ohio State University, Columbus, OH 43210, USA
Submitted to: The Astronomical Journal
Preprint available on the web at
http://arxiv.org/abs/0712.1261
Amorphization of Crystalline Water Ice
Weijun Zheng1,2,3, David Jewitt1, and Ralf I. Kaiser2
1 Institute for Astronomy, University of Hawaii, Honolulu, HI 96822, USA
2 Department of Chemistry, University of Hawaii, Honolulu, HI 96822, USA
3 State Key Laboratory of Molecular Reaction Dynamics, Institute of Chemistry,
Chinese Academy of Sciences, Beijing 100080, P. R. China
Preprint available on the web at
http://arxiv.org/abs/0801.2805
Detection of Small Kuiper Belt Objects by Stellar Occultations
R.Stevenson1
1 Institute for Astronomy, 2680 Woodlawn Drive, University of Hawaii, Honolulu, HI 96822, USA
To appear in: Proc. of the 14th Young Scientists Conference on Astronomy and Space Physics
Preprint available on the web at
http://arxiv.org/abs/0712.1550
The University of Arizona Press in collaboration with the Lunar and Planetary Institute, 2008
CONTENTS
PART I: INTRODUCTION
PART II: TRANSNEPTUNIAN OBJECT POPULATIONS
PART III: BULK PROPERTIES
PART IV: PHYSICAL PROCESSES
PART V: FORMATION AND EVOLUTION
PART VI: INDIVIDUALITIES AND PECULIARITIES
PART VII: LINKS WITH OTHER SOLAR SYSTEM POPULATIONS
PART VIII: BOUNDARIES AND CONNECTIONS TO OTHER STELLAR SYSTEMS
PART IX: LABORATORY
PART X: PERSPECTIVES
The results of a search for kilometer-sized Kuiper Belt Objects (KBOs)
with the method of serendipitous stellar occultations are reported.
Photometric time-series were obtained at the Dominion Astrophysical
Observatory (DAO) in Victoria, British Columbia, and were analyzed
for the presence of occultation events. Observations were performed
at 40 Hz and included a total of 5.0 star-hours for target stars
in the ecliptic open cluster M35, and 2.1 star-hours for control
stars in the off-ecliptic open cluster M34. To evaluate the
recovery fraction of the analysis method, and thereby determine
the limiting detectable size, artificial occultation events were
added to the data. No viable candidate occultation events were
detected. This limits the cumulative surface density of KBOs to
3.5 x 1010 deg-2 (95% confidence) for KBOs brighter
than mR=35.3 (larger than 860 m in diameter, assuming a
geometric albedo of 0.04 and a distance of 40 AU). To evaluate
false-positive rates, a method of simulating scintillation effects
was developed.
Dissertation directed by D.L. Welch and J-J. Kavelaars
Ph.D. awarded May, 2007 from McMaster University
Available in postscript or PDF, contact bick@astro.princeton.edu
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.
