A Deep Search for Additional Satellites around the Dwarf Planet Haumea
Haumea is a dwarf planet with two known satellites, an unusually high spin rate, and a large collisional family, making it one of the most interesting objects in the outer solar system. A fully self-consistent formation scenario responsible for the satellite and family formation is still elusive, but some processes predict the initial formation of many small moons, similar to the small moons recently discovered around Pluto. Deep searches for regular satellites around Kuiper belt objects are difficult due to observational limitations, but Haumea is one of the few for which sufficient data exist. We analyze Hubble Space Telescope (HST) observations, focusing on a 10-consecutive-orbit sequence obtained in 2010 July, to search for new very small satellites. To maximize the search depth, we implement and validate a nonlinear shift-and-stack method. No additional satellites of Haumea are found, but by implanting and recovering artificial sources, we characterize our sensitivity. At distances between ~10,000 and ~350,000 km from Haumea, satellites with radii as small as ~10 km are ruled out, assuming an albedo (p ≃ 0.7) similar to Haumea. We also rule out satellites larger than ≳40 km in most of the Hill sphere using other HST data. This search method rules out objects similar in size to the small moons of Pluto. By developing clear criteria for determining the number of nonlinear rates to use, we find that far fewer shift rates are required (~35) than might be expected. The nonlinear shift-and-stack method to discover satellites (and other moving transients) is tractable, particularly in the regime where nonlinear motion begins to manifest itself.
Additional Information© 2016 The American Astronomical Society. Received 2015 July 10; accepted 2016 March 27; published 2016 May 27. We thank Alex Parker, Danielle Hastings, and the anonymous referee for discussions and suggestions that improved the manuscript. D.R. acknowledges the support of a Harvard Institute for Theory and Computation Fellowship. This work is based on NASA/ESA Hubble Space Telescope Program 12243. Support was provided by NASA through grants HST-GO-12243 from the Space Telescope Science Institute (STScI), which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555.
Published - aj_151_6_162.pdf
Submitted - 1605.03941v1.pdf