2003/05/30 by T. Grav, Matthew J. Holman, M. J. Holman +2 · 4 citations
Biochemistry, Genetics and Molecular Biology · Physics and Astronomy · #Astro and Planetary Science #Geomagnetism and Paleomagnetism Studies #Planetary Science and Exploration #astro-ph
paper · pdf · doi:10.1086/377067
published as Astrophys.J. 591 (2003) L71-L74 · Accepted by ApJ Letters, 11 pages (incl. 1 figure)
arxiv created 2003/05/30 · openalex publication_date 2003/06/04 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/31
We determine the period, p = 11.52 ± 0.14 hr, and a light-curve peak-to-peak amplitude, a = 0.029 ± 0.003 mag, of the Neptunian irregular satellite Nereid. If the light-curve variation is due to albedo variations across the surface, rather than solely to the shape of Nereid variations, the rotation period would be a factor of 2 shorter. In either case, such a rotation period and light-curve amplitude, together with Nereid's orbital period, p = 360.14 days, imply that Nereid is almost certainly in a regular rotation state, rather than the chaotic rotation state suggested in work of Schaefer & Schaefer and of Dobrovolskis. Assuming that Nereid is perfectly spherical, the albedo variation is 3% across the observed surface. Assuming a uniform geometric albedo, the observed cross-sectional area varies by 3%. We caution that the light curve found in this Letter only sets limits on the combination of albedo and physical irregularity and that we cannot determine the orientation of Nereid's spin axis from our data.