Astrophysics, abstract
astro-ph/0602543

From: Imre Nagy [view email]

Date (v1): Fri, 24 Feb 2006 16:59:42 GMT (402kb)
Date (revised v2): Mon, 27 Feb 2006 16:31:00 GMT (393kb)

Pluto's moon system: survey of the phase space I

Authors: I. Nagy, A. Suli, B. Erdi

Comments: 5 pages, 3 figures

The dynamical structure of the phase space of the Pluto--Charon system is studied in the model of the spatial circular restricted three-body problem by using numerical methods. With the newly discovered two small satellites S/2005 P1 and S/2005 P2, the Pluto--Charon system can be considered the first binary system in which celestial bodies move in P-type orbits. It is shown that the two satellites are in the stable region of the phase space and their origin by capture is unlikely. Also the large mass parameter allows to regard the satellites as a model of a new class of exoplanets orbiting around stellar binary systems.

http://arxiv.org/abs/astro-ph/0602543

Astrophysics, abstract
astro-ph/0602546

From: H. B. Hammel [view email]

Date: Fri, 24 Feb 2006 18:28:44 GMT (945kb)

Mid-Infrared Ethane Emission on Neptune and Uranus

Authors: H. B. Hammel, D. K. Lynch, R. W. Russell, M. L. Sitko, L. S. Bernstein, T. Hewagama

Comments: Accepted for publication in ApJ. 16 pages, 10 figures, 2 tables

We report 8- to 13-micron spectral observations of Neptune and Uranus from the NASA Infrared Telescope Facility spanning more than a decade. The spectroscopic data indicate a steady increase in Neptune's mean atmospheric 12-micron ethane emission from 1985 to 2003, followed by a slight decrease in 2004. The simplest explanation for the intensity variation is an increase in stratospheric effective temperature from 155 +/- 3 K in 1985 to 176 +/- 3 K in 2003 (an average rate of 1.2 K/year), and subsequent decrease to 165 +/- 3 K in 2004. We also detected variation of the overall spectral structure of the ethane band, specifically an apparent absorption structure in the central portion of the band; this structure arises from coarse spectral sampling coupled with a non-uniform response function within the detector elements. We also report a probable direct detection of ethane emission on Uranus. The deduced peak mole fraction is approximately an order of magnitude higher than previous upper limits for Uranus. The model fit suggests an effective temperature of 114 +/- 3 K for the globally-averaged stratosphere of Uranus, which is consistent with recent measurements indicative of seasonal variation.

http://arxiv.org/abs/astro-ph/0602546

General Relativity and Quantum Cosmology, abstract
gr-qc/0602095

From: Lorenzo Iorio [view email]

Date: Thu, 23 Feb 2006 15:28:02 GMT (4kb)

Solar System planetary orbital motions and dark matter

Authors: Lorenzo Iorio

Comments: Latex, 5 pages, 2 tables, no figures, 4 references

In this brief note we explicitly work out the effects that a spherically symmetric distribution of dark matter would induce on the Keplerian orbital elements of the Solar System planets and compare them with the latest results in planetary orbit determination from the EPM2004 ephemerides. It turns out that the longitudes of perihelia and the mean longitudes are affected by secular precessions. The resulting upper bounds on dark matter density, obtained from the EPM2004 formal errors in the determined mean longitude shifts over 90 years, lie in the range 10^-19-10^-20 g cm^-3 with a peak of 10^-22 g cm^-3 for Mars. Even if realistic errors on mean longitudes may be one order of magnitude larger, such results are up to 2-3 orders of magnitude better than other Solar System-based constraints.

http://arxiv.org/abs/gr-qc/0602095