Paper: astro-ph/0604552

Date: Wed, 26 Apr 2006 20:27:17 GMT (73kb)

Title: A Survey for "Normal" Irregular Satellites Around Neptune: Limits to
Completeness

Authors: Scott S. Sheppard (Carnegie Inst. of Wash.), David C. Jewitt and Jan
Kleyna

Comments: 10 pages, 9 figures (6 color), 3 tables; Accepted for the July 2006
Astronomical Journal
\\
We surveyed 1.75 square degrees of sky near Neptune to an R-band 50%
detection efficiency of 25.8 mags (corresponding to radii of about 17 km for an
assumed albedo of 0.04). We discovered one new outer satellite, Psamathe
(S/2003 N1), about 20 km in radius and having a distant retrograde orbit and
moderate eccentricity. Until 2003 Neptune was only known to have two satellites
which exhibited orbital signatures indicative of capture. Both of these, Triton
and Nereid, are unusual when compared to the irregular satellites of other
giant planets. With recent discoveries of four additional satellites by Holman
et al. (2004) it is now apparent that Neptune has a distant ``normal''
irregular satellite system in which the satellites have radii and orbital
properties similar to those of the satellites of other giant planets. We find
that the satellite size distribution at Neptune is not well determined given
the few objects known to date, being especially sensitive to the inclusion of
Triton and Nereid in the sample. Finally, we note that Psamathe and S/2002 N4
have similar semi-major axes, inclinations and eccentricities. They may be
fragments of a once larger satellite.

\\ ( http://arXiv.org/abs/astro-ph/0604552 , 73kb)