2016/01/11 by Csaba Kiss, Cs. Kiss, A. Pál +15 · 2 citations
Physics and Astronomy · #Astro and Planetary Science #Solar and Space Plasma Dynamics #Stellar, planetary, and galactic studies #astro-ph.EP
paper · pdf · doi:10.1093/mnras/stw081
Accepted for publication in MNRAS
arxiv created 2016/01/11 · openalex publication_date 2016/02/20 · arxiv updated 2016/03/09 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/01
In this paper we present an analysis of Kepler K2 mission Campaign 3 observations of the irregular Neptune satellite, Nereid. We determined a rotation period of P=11.594(+/-)0.017 h and amplitude of dm=0.0328(+/-)00018, confirming previous short rotation periods obtained in ground based observations. The similarities of light curve amplitudes between 2001 and 2015 show that Nereid is in a low-amplitude rotation state nowadays and it could have been in a high-amplitude rotation state in the mid 1960's. Another high-amplitude period is expected in about 30 years. Based on the light curve amplitudes observed in the last 15 years we could constrain the shape of Nereid and obtained a maximum a:c axis ratio of 1.3:1. This excludes the previously suggested very elongated shape of a:c=1.9:1 and clearly shows that Nereid's spin axis cannot be in forced precession due to tidal forces. Thermal emission data from the Spitzer Space Telescope and the Herschel Space Observatory indicate that Nereid's shape is actually close to the a:c axis ratio limit of 1.3:1 we obtained, and it has a very rough, highly cratered surface