[FPSPACE] The water ice rich surface of (145453) 2005 RR43: a case for a population of tra

[LARRY KLAES]

Astrophysics, abstract
astro-ph/0703098

From: Noemi Pinilla-Alonso [view email]

Date: Tue, 6 Mar 2007 00:36:32 GMT   (26kb)

The water ice rich surface of (145453) 2005 RR43: a case for a population of 
trans-neptunian objects?

Authors: N. Pinilla-Alonso (1), J. Licandro (2,3), R. Gil-Hutton (4), R. 
Brunetto (5,6) ((1) Fundacion Galileo Galilei, (2) Isaac Newton Group, (3) 
Instituto de Astrofisica de Canarias, (4) Complejo Astronomico el Leoncito, 
(5) Dipartamento di Fisica, Universita di Lecce, (6) INAF-Osservatorio 
Astrofisico di Catania)

Comments: 5 pages, 3 figures submitted to Astronomy & Astrophysics

Recent results suggest that there is a group of trans-Neptunian objects 
(TNOs) (2003 EL61 being the biggest member), with surfaces composed of 
almost pure water ice and with very similar orbital elements. We study the 
surface composition of another TNO that moves in a similar orbit, (145453) 
2005 RR43, and compare it with the surface composition of the other members 
of this group. We report visible and near-infrared spectra in the 
0.53-2.4\mu spectral range, obtained with the 4.2m William Herschel 
Telescope and the 3.58m Telescopio Nazionale Galileo at the "Roque de los 
Muchachos" Observatory (La Palma, Spain). The spectrum of 2005 RR43 is 
neutral in color in the visible and dominated by very deep water ice 
absorption bands in the near infrared (D= 70.3 +/- 2.1 % and 82.8 +/- 4.9 % 
at 1.5 \mu and 2.0 \mu respectively). It is very similar to the spectrum of 
the group of TNOs already mentioned. All of them present much deeper water 
ice absorption bands (D>40 %) than any other TNO except Charon. Scattering 
models show that its surface is covered by water ice, a significant fraction 
in crytalline state with no trace (5 % upper limit) of complex organics. 
Possible scenarios to explain the existence of this population of TNOs are 
discussed: a giant collision, an originally carbon depleted composition, or 
a common process of continuous resurfacing. We conclude that TNO 2005 RR43 
is member of a group, may be a population, of TNOs clustered in the space of 
orbital parameters that show abundant water ice and no signs of complex 
organics and which origin needs to be further investigated. A carbon 
depleted population of TNOs could be the origin of the population of carbon 
depleted Jupiter family comets already noticed by A'Hearn et al. (1995).

http://arxiv.org/abs/astro-ph/0703098