The big news since the previous issue of the Newsletter is the multiplicity of large TNOs:
Two's company, three's a crowd...
In IAUC 08625, Hal Weaver, Alan Stern, et al. announced the discovery of two more
satellites around Pluto, making it a quadruple system. The observations
were made with HST; the separations of the two new satellites are on the order of
2 arcsec from Pluto, with magnitudes of 
23.0 and 23.4 mag. Initial
analysis indicates the two new satellites are in
nearly circular orbits in Pluto's equatorial plane, with semi-major axes around
49,500 and 64,700 km, corresponding to orbital periods of approximately 25.5 and
38.2 days, respectively.
IAUC: http://cfa-www.harvard.edu/iauc/08600/08625.html
HST press release: http://hubblesite.org/newscenter/newsdesk/archive/releases/2005/19/
More information at: http://www.boulder.swri.edu/plutonews
In IAUC 8610, Mike Brown et al. announced the discovery that 2003 UB313 is a binary. The satellite K'-band magnitude was 4.43 mag fainter than the primary and at a separation of 0.53 arcsec. [A preprint of the submitted paper is listed in this issue of the newsletter.]
IAUC: http://cfa-www.harvard.edu/iauc/08600/08610.html
More information at: http://www.gps.caltech.edu/~mbrown/planetlila/moon/index.html
There were 12 new TNO discoveries announced since the previous issue of Distant EKOs:
2005 PK21, 2005 PL21, 2005 PM21, 2005 PN21, 2005 PO21, 2005 PP21, 2005 PQ21, 2005 PR21, 2005 PS21, 2005 PT21, 2005 PU21, 2005 TN74
and no new Centaur/SDO discoveries.
Current number of TNOs: 913 (and Pluto & Charon & two friends, and 14 other TNO binary companions)
Current number of Centaurs/SDOs: 153
Current number of Neptune Trojans: 2
Out of a total of 1068 objects:
499 have measurements from only one opposition
414 of those have had no measurements for more than a year
206 of those have arcs shorter than 10 days
(for more details, see:
http://www.boulder.swri.edu/ekonews/objects/recov_stats.gif)
We have analyzed a homogeneous set of observations of eighty-one
transneptunian objects obtained with the NIC2 camera on the Hubble
Space Telescope with the goal of identifying partially resolved
binaries. Using PSF-fitting we have identified six likely binaries in
addition to the three new binaries already found in this data set. We
find that 11
% of transneptunian objects are binaries
at separation and brightness limits of the NIC2 camera. The
identification of these new binaries significantly increases the known
lower limit to the binary fraction among transneptunian objects. The
origin of such a high fraction of binaries remains to be determined.
Most interestingly, detectable binaries appear to be about four times
more common among the cold classical disk than in the dynamically
excited populations.
To appear in: The Astronomical Journal
For preprints, contact stephens@pha.jhu.edu
We report high precision photometry of three small and one larger Kuiper Belt Objects (KBOs) obtained with the Advanced Camera for Surveys onboard the Hubble Space Telescope (ACS/HST). The three small bodies are the smallest KBOs for which lightcurve measurements are available. 2003 BF91 has a diameter of 20 kilometers (assuming 10% albedo) and a 1.09 magnitude, 9.1-hour lightcurve that is feasibly explained by the rotation of an elongated, coherent body that is supported by material strength and best imagined as an icy outer Solar System analog to asteroid (243) Ida. Two other small KBOs, 2003 BG91 and 2003 BH91 (diameters 31 and 18 km, with albedo 10%), exhibit an unremarkable lightcurve and no detectable photometric variation, respectively. For the larger KBO 2000 FV53 (116 km diameter, assuming 10% albedo) we strongly detect a non-sinusoidal periodic (7.5 hours) brightness variation with a very small amplitude (0.07 mag). This KBO may be nearly spherical, a result that might not be unusual in the Kuiper Belt but would be remarkable among outer Solar System satellites of similar size.
Lightcurves may be caused by variations in albedo or shape, and we carry out a study of possible physical states and bulk densities under the assumptions of both fluid equilibrium and finite, non-zero internal friction. Under most assumptions, the densities for the these KBOs are likely to be in the range 1-2 g cm-3, and a plausible solution for 2000 FV53 is a rubble pile of this density that is held slightly out of the minimum-energy shape by internal friction among constituent blocks that are relatively small. Our interpretation of 2000 FV53 as a pulverized but essentially primordial object and 2003 BF91 as a collisional fragment is consistent with models of collisional timescales in the outer Solar System. We compile all published KBO lightcurve data to date and compare our results to the larger population.
To appear in: The Astronomical Journal
Preprints available on the web at http://arxiv.org/abs/astro-ph/0510454
Discovery of a Planetary-sized Object in the Scattered Kuiper Belt
M.E. Brown1, C.A. Trujillo2, and D.L. Rabinowitz3
1 Division of Geological and Planetary Sciences, California Institute
of Technology, Pasadena, CA 91125, USA
2 Gemini Observatory, 670 North A'ohoku Place,
Hilo, HI 96720, USA
3 Department of Physics, Yale University, New
Haven, CT 06520, USA
Submitted to: The Astrophysical Journal letters
For preprints, contact mbrown@caltech.edu
or on the web at http://arxiv.org/abs/astro-ph/0508633
Photometric Observations Constraining the Size, Shape, and Albedo of 2003 El61, a Rapidly Rotating, Pluto-Sized Object in the Kuiper Belt
David L. Rabinowitz1, Kristina Barkume2, Michael E. Brown2,
Henry Roe2,
Michael Schwartz3, Suzanne Tourtellotte4, and Chad Trujillo5
1 Yale University, Yale Center for Astronomy & Astrophysics,
P.O. Box 208121, New Haven, CT, USA
06520-8121
2 Division of Geological and Planetary Sciences, California
Institute of Technology, Pasadena, CA 91125, USA
3 Tenagra Observatory, C2 Box 292, Nogales, Arizona, 85621, USA
4 Yale University, Astronomy Department, P.O. Box 208121,
New Haven CT 06520-8121, USA
5 Gemini Observatory, 670 North AĠohoku Place, Hilo, HI 96720, USA
Submitted to: The Astrophysical Journal
For preprints, contact david.rabinowitz@yale.edu
or on the web at http://arxiv.org/abs/astro-ph/0509401
Satellites of the Largest Kuiper Belt Objects
M.E. Brown1, M.A. van Dam2, A.H. Bouchez2,3,
D. LeMignant2, R.D. Campbell2, J.C.Y. Chin2,
A. Conrad2, S.K. Hartman2, E.M. Johansson2,
R.E. Lafon2,
D.L. Rabinowitz4, P.J. Stomski2,
D.M. Summers2, C.A. Trujillo5, and P.L. Wizinowich2
1 Division of Geological and Planetary Sciences, California Institute
of Technology, Pasadena, CA 91125, USA
2 W.M. Keck Observatory, 65-1120 Mamalahoa
Highway, Kamuela, HI 96743, USA
3 Caltech Optical Observatories, California
Institute of Technology, Pasadena, CA 91125, USA
4 Department of Physics, Yale University, New
Haven, CT 06520, USA
5 Gemini Observatory, 670 North A'ohoku Place,
Hilo, HI 96720, USA
Submitted to: Astrophysical Journal Letters
For preprints, contact mbrown@caltech.edu
or on the web at http://arxiv.org/abs/astro-ph/0510029
The Methane Ice Rich Surface of the Large TNO 2005 FY9:
A Pluto-twin in the Trans-neptunian Belt?
J. Licandro1,2, N. Pinilla-Alonso3,2, M. Pedani3,
E. Oliva3, G.P. Tozzi4, and W.M. Grundy5
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 Fundación Galileo Galilei & Telescopio
Nazionale Galileo, P.O.Box 565, E-38700, S/C de La Palma, Tenerife, Spain
4 INAF-Osservatorio Astrofisico di Arcetri, Largo e Fermi 5, 50125,
Firenze, Italy
5 Lowell Observatory, 1400 West Mars Hill Road, Flagstaff, AZ 86001-4470, USA
Submitted to: Astronomy & Astrophysics Letters
For preprints, contact licandro@ing.iac.es
http://www.wiley.com/WileyCDA/WileyTitle/productCd-3527405569.html
The second edition of this book has expanded material and a new chapter, reflecting new understanding of Pluto since 1997 and the New Horizons mission.
Chapters:
Prologue: Encounter!
Introduction
Chapter 1: New Frontier
Chapter 2: First Facts
Chapter 3: A Distant Dance
Chapter 4: The Importance of Snow
Chapter 5: Building a Binary Planet
Chapter 6: Ice Fields and Ice Dwarfs
Chapter 7: Everest
Chapter 8: New Horizons
Chapter 9: Where No One Has Gone Before
Appendix: A Chronology of Major Events in the Exploration of Pluto
Further Reading
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.