2005/09/30 by David L. Rabinowitz, Kristina Barkume, Michael E. Brown +4 · 4 citations
Engineering · Physics and Astronomy · #Astro and Planetary Science #Planetary Science and Exploration #Spacecraft Dynamics and Control #astro-ph
paper · pdf · doi:10.1086/499575
published as Astrophys.J.639:1238-1251,2006 · 27 pages, six figures
arxiv created 2005/11/08 · openalex publication_date 2006/03/06 · arxiv updated 2010/11/11 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/31
We present measurements at optical wavelengths of the spectral reflectance, rotational light curve, and solar phase curve of 2003 EL61. With apparent visual magnitude 17.5 at 51 AU from the Sun, this newly discovered member of the classical Kuiper Belt is now the third brightest KBO after Pluto and 2005 FY9. Our observations reveal an unambiguous, double-peaked rotational light curve with period 3.9154 ± 0.0002 hr and peak-to-peak amplitude 0.28 ± 0.04 mag. This is the fastest rotation period reliably determined for any body in the solar system larger than 100 km. Assuming the body has relaxed over time to the shape taken by a homogenous fluid body, our observations tightly constrain the shape and density. Given the mass we recently determined for 2003 EL61 from the orbit of a small satellite, we also constrain the size and albedo. We find a total length of 1960-2500 km, a mean density of 2600-3340 kg m -3 , and a visual albedo greater than 0.6. We also measure a neutral reflectance at visible wavelengths and a linear phase curve with slope varying from 0.09 mag deg -1 in the B band to 0.13 mag deg -1 in the I band. The absolute V -band magnitude is 0.444 ± 0.021.