There were 3 new TNO discoveries announced since the previous issue of Distant EKOs:
2002 XP114, 2004 NE32, 2004 OL12
and 1 new Centaur/SDO discovery:
2004 PY42
Reclassified objects:
2003 QA91 (SDOTNO)
2003 QB92 (SDO
2004 EG96 (TNO
Objects recently assigned numbers:
2001 KF77 = (88269)
2000 OO67 = (87269)
2000 QB243 = (87555)
2003 VB12 = (90377)
1998 HP151 = (85627)
1998 KR65 = (85633)
1999 OY3 = (86047)
1999 RY215 = (86177)
2001 KE76 = (88267)
2001 KK76 = (88268)
2001 QT297 = (88611)
2004 DW = (90482)
2004 GV9 = (90568)
Re-identified objects:
2002 GX32 = 1994 JV (SDO)
Current number of TNOs: 800 (and Pluto & Charon, and 12 other TNO binary companions)
Current number of Centaurs/SDOs: 147
Current number of Neptune Trojans: 1
Out of a total of 948 objects:
463 have measurements from only one opposition
354 of those have had no measurements for more than a year
199 of those have arcs shorter than 10 days
(for more details, see:
http://www.boulder.swri.edu/ekonews/objects/recov_stats.gif)
We have measured the separations and position angles of the two
components of the binary transneptunian object (58534) 1997 CQ29
at eight epochs. From these data we are able to constrain the orbit
and mass of this binary system. The best fitting orbit has an orbital
period of P = 312
3 days. The orbital eccentricity is
e = 0.450.03 and the semimajor axis is a = 8,01080 km.
The mass of the system is surprisingly low at 0.420.02
x
1018 kg. To account for the observed brightness consistent with
the low mass and a range of plausible densities, the geometric albedo
must be very high; for an assumed density of 1000 kg m-3 we find
a red geometric albedo of pR = 0.37, an order of magnitude higher
than has been generally assumed for transneptunian objects. If
objects with comparably high albedos are common in the Kuiper belt,
estimates of the mass of the belt must be significantly reduced. The
semimajor axis of (58534) 1997 CQ29's orbit is 2.8% of the Hill
radius of the primary, a value strikingly similar to this same ratio
in other transneptunian binaries, main-belt binaries, and regular
satellite systems.
To appear in: Icarus
For preprints, contact Keith Noll noll@stsci.edu
We investigate the effect that a close stellar encounter would have on the growing scattered disk and Oort cloud. Such an encounter has been suggested as the cause of the Kuiper belt's outer edge (Melita et al. 2002). Thus, we restrict our study to encounters that could have caused such a structure. We find that we probably can rule out all such encounters that occurred either at or subsequently to 10 million years after the Oort cloud started to form. In our simulations, these encounters either produce an extended scattered disk that is too populous to be consistent with observations or produces an Oort cloud that is too anemic.
To appear in: The Astronomical Journal
Preprints on the web at
http://www.boulder.swri.edu/~hal/passing_star.html
Large-scale simulations of the Centaur population are carried out. The
evolution of 23,328 particles based on the orbits of 32 well-known
Centaurs is followed for up to 3 Myr in the forward and backward
direction under the influence of the four massive planets. The objects
exhibit a rich variety of dynamical behaviour with half-lives ranging
from 540 kyr (1996 AR20) to 32 Myr (2000 FZ53). The mean half-life of
the entire sample of Centaurs is 2.7 Myr. The data are analysed using
a classification scheme based on the controlling planets at perihelion
and aphelion, previously given in Horner et al. Tranfer probabilities
are computed and show the main dynamical pathways of the Centaur
population. The total number of Centaurs with diameters larger than
1 km is estimated as 
44,300, assuming an inward flux of one new
short-period comet every 200 yr. The flux into the Centaur region from
the Edgeworth-Kuiper Belt is estimated to be one new object every
125 yr. Finally, the flux from the Centaur region to Earth-crossing
orbits is one new Earth-crosser every 880 yr.
To appear in: Monthly Notices of the Royal Astronomical Society
For preprints, contact horner@phim.unibe.ch
or on the web at http://arxiv.org/abs/astro-ph/0407400
Detailed orbit integrations of clones of five Centaurs -- namely,
1996 AR20, 2060 Chiron, 1995 SN55, 2000 FZ53 and 2002 FY36 -- for
durations of 3 Myr are presented. One of our Centaur sample
starts with perihelion initially under the control of Jupiter
(1996 AR20), two start under the control of Saturn (Chiron and
1995 SN55) and one each starts under the control of Uranus (2000 FZ53)
and Neptune (2002 FY36) respectively. A variety of interesting
pathways are illustrated with detailed examples including: capture
into the Jovian Trojans, repeated bursts of short-period comet
behaviour, capture into mean-motion resonances with the giant planets
and into Kozai resonances, as well as traversals of the entire Solar
system. For each of the Centaurs, we provide statistics on the numbers
(i) ejected, (ii) showing short-period comet behaviour and (iii)
becoming Earth and Mars crossing. For example, Chiron has over 60% of
its clones becoming short-period objects, whilst 1995 SN55 has over
35%. Clones of these two Centaurs typically make numerous close
approaches to Jupiter. At the other extreme, 2000 FZ53 has 2% of its
clones becoming short-period objects. About 20% of the clones which
become short-period comets subsequently evolve into Earth-crossers.
To appear in: Monthly Notices of the Royal Astronomical Society
For preprints, contact horner@phim.unibe.ch
or on the web at http://arxiv.org/abs/astro-ph/0408576
Explaining the origin of the orbits of 2000 CR105 (
AU,
AU) and 2003 VB12 (a=531 AU, q=74 AU, unofficially
known as Sedna) is a major test for our understanding of the
primordial evolution of the outer Solar System. Gladman et al. (2001)
showed that 2000 CR105 could not have been a normal member of the
scattered disk that had its perihelion distance increased by chaotic
diffusion. The same conclusion also clearly applies to 2003 VB12. In
this paper we explore five seemingly promising mechanisms for
explaining the origin of the orbits of these peculiar objects: (i) the
passage of Neptune through a high-eccentricity phase, (ii) the past
existence of massive planetary embryos in the Kuiper belt or the
scattered disk, (iii) the presence of a massive trans-Neptunian disk
at early epochs that perturbed high-inclined scattered disk objects,
(iv) encounters with other stars that perturbed the orbits of some of
the Solar System's trans-Neptunian planetesimals, and (v) the capture
of extra-solar planetesimals from low mass stars or brown dwarfs
encountering the Sun. Of all these mechanisms, the ones giving the
most satisfactory results are those related to the passages of stars
(iv and v). An important advantage of both stellar passage scenarios
is that all the resulting objects with large perihelion distances also
have large semi-major axes. This is in good agreement with the fact
that 2000 CR105 and 2003 VB12 have semi-major axes larger
than 200 AU and no other bodies with similar perihelion distances but
smaller semi-major axes have yet been discovered. We favor (iv), since
it produces an orbital element distribution that is more consistent
with the observations, unless 2000 CR105 and 2003 VB12
represent a population more massive than a few tenths of an Earth
mass, in which case (iv) is not viable.
To appear in: The Astronomical Journal
Preprints on the web at
http://www.boulder.swri.edu/~hal/CR105.html
and
http://www.arXiv.org/abs/astro-ph/0403358
Trans-neptunian Object (55636) 2002 TX300 :
A Fresh Icy Surface in
the Outer Solar System
J. Licandro1,2, L. di Fabrizio3, N. Pinilla-Alonso3, L.M. Lara4, J. de León2, A. García1, and E. Oliva3
1 Isaac Newton Group, P.O.Box 321, E-38700, Santa Cruz de La Palma,
Tenerife, Spain
2 Instituto de Astrofísica de Canarias, c/Vía Láctea s/n,
E38205, La Laguna, Tenerife, Spain
3 Centro Galileo Galilei & Telescopio
Nazionale Galileo, P.O.Box 565, E-38700, S/C de La Palma,
Tenerife, Spain
4 Instituto de Astrofísica de Andalucía, CSIC,
Camino Bajo de Huétor 24, 18008 Granada, Spain
Submitted to: Astronomy & Astrophysics Letters
For preprints, contact licandro@ing.iac.es
The Inhomogeneous Surface of Centaur (32522) Thereus 2001 PT13
J. Licandro1,2 and N. Pinilla-Alonso3
1 Isaac Newton Group, P.O.Box 321, E-38700, Santa Cruz de La Palma,
Tenerife, Spain
2 Instituto de Astrofísica de Canarias, c/Vía Láctea s/n,
E38205, La Laguna, Tenerife, Spain
3 Centro Galileo Galilei & Telescopio
Nazionale Galileo, P.O.Box 565, E-38700, S/C de La Palma,
Tenerife, Spain
Submitted to: Astrophysical Journal Letters
For preprints, contact licandro@ing.iac.es
The Origin of Asymmetric Capture in Migratory Resonances
Ruth A. Murray-Clay1 and Eugene I. Chiang1,2
1 Center for Integrative Planetary Sciences, Astronomy Department,
University of California at Berkeley, Berkeley, CA 94720, USA
2 Alfred P. Sloan Research Fellow
Submitted to: The Astrophysical Journal
For preprints, contact rmurray@astro.berkeley.edu
or on the web at
http://astron.berkeley.edu/~rmurray/publications.html
King of the Kuiper Belt
Diana Whitman
Published in: Mercury, 33, 17 (2004 May/June)
Comet Nucleus Size Distributions from HST and Keck Telescopes
K.J. Meech1, O.R. Hainaut2, and B.G. Marsden3
1University Hawaii, Institute for Astronomy, 2680 Woodlawn Drive,
Honolulu, HI 96822, USA
2European Southern Observatory, Casilla 19001, Santiago, Chile
3Harvard-Smithsonian Center for Astrophysics, 60 Garden Street,
Cambridge, MA 02138, USA
Published in: Icarus, 170, 463 (2004 August)
Pumping of a Planetesimal Disc by a Rapidly Migrating Planet
R.G. Edgar1 and P. Artymowicz1
1Stockholm Observatory, SCFABSE-10691 Stockholm, Sweden
To appear in: The Monthly Notices of the Royal Astronomical Society
For preprints contact: rge21@astro.su.se
Available online at: http://arxiv.org/abs/astro-ph/0409017
Formation and Migration of Trans-Neptunian Objects
S.I. Ipatov1
1 George Mason University, USA
To appear in: Proceedings of the 14th Annual Astrophysics Conference in Maryland; ``The Search for Other Worlds'', ed. by S.S. Holt and D. Deming, American Institute of Physics, 2004, pp. 277-280
For preprints, contact ipatov@stars.gsfc.nasa.gov
or on the web at http://www.arXiv.org/abs/astro-ph/0401279
We carried out extensive numerical orbit integrations to probe the long-term chaotic dynamics of the 2:3 (Plutinos) and 1:2 (Twotinos) mean motion resonances with Neptune. We derive maps of resonance stability measured both by time-averaged particle density and by mean dynamical diffusion rate, and investigate the effects of a massive perturber embedded in the resonance. We also investigate the population of Resonant Kuiper Belt Objects at 4 Gyr ago compared to the present, and discuss the implications for theories of Kuiper Belt origins.
We have numerically investigated the long term dynamical behavior of known Centaurs. We find that their orbital evolution is characterized by frequent close encounters with the giant planets, with no significant long-term resonant behavior. Most of these Centaurs will escape from the inner solar system, while a fraction will enter the Jupiter-family comet (JFC) population and a few percent will impact a giant planet. We discuss the implications of our study for the spatial distribution of the actual Centaur population.
Using numerical and analytical models, we investigate the ejection of water molecules from Europa's surface by sputtering, the subsequent evolution of their ballistic trajectories, and their re-deposition onto the surface as a water frost. We conclude that net deposition does occur under certain conditions, making sputtering erosion and re-deposition a plausible explanation for the observed color dichotomy between Europa's leading and trailing hemispheres.
During Cassini's approach to Jupiter, a series of images was taken to
search for any undiscovered satellites of Jupiter. Our analysis of
these images indicates that no undiscovered satellites exist between
2.6 and 20 RJ with inclination
, eccentricity e <
0.0002, diameter D > 15 km and albedo A > 0.1.
Dissertation directed by Renu Malhotra.
Ph.D. awarded in August, 2004, from the University of Arizona.
Current Address: 322 Space Sciences, Cornell University, Ithaca,
NY 14853, USA
For reprints, contact matthewt@astro.cornell.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.
