An exploration of Pluto’s environment through stellar occultations

Abstract

Context. Pluto has five known satellites with diameters ranging from ∼1200 km down to ∼40 km, a possible outcome of a collisional origin. Smaller objects probably exist and may maintain tenuous rings, thus representing hazards during the New Horizons flyby of July 2015. Aims. The goal is to provide an upper limit for the numbers of unseen small bodies and/or equivalent widths of putative Pluto rings. Methods. We use a Pluto stellar appulse on April 10, 2006, and a stellar occultation by the dwarf planet on June 14, 2007, to scan Pluto's surroundings. Results. Our best data set places a 3σ upper limit of 0.3 km for the radius of isolated moonlets that we can detect. In the absence of detection, we derive an upper limit of 15 000 for the number of such bodies at distances smaller than ∼70 000 km from Pluto's system barycenter. We place a 3σ upper limit of typically 30−100 m for the equivalent width of ring material at barycentric distances ranging from 13 000 to 70 000 km. This limit applies for narrow rings only, i.e. less than about 10 km in width.

Uniform asymptotics of paraxial boundary diffraction waves

“…One of the motivations of the present work has to do with the possibility of grasping the basic features of the wavefields scattered from "large" tridimensional objects in terms of paraxial diffraction from equivalent planar apertures, a topic that continues to receive attention, even in recent times [40], also in light of its intriguing astronomical applications [41]. In particular, we believe that the approach outlined here could be helpful in the study of diffraction effects observed during celestial occultation experiments [42][43][44][45][46].…”

Search for signatures of dust in the Pluto–Charon system usingHerschel/PACS observations

“…They placed a 3σ upper limit on the azimuthally averaged normal I/F of ring particles of 5.1 × 10 7 at a distance of 42 000 km from the Pluto-Charon barycentre. Boissel et al (2014) derive an upper limit of 15 000 for the number of bodies smaller than 0.3 km at distances smaller than 70 000 km from Pluto's system barycentre. The impactor velocity of colliding bodies ranges from 10−100 m s −1 (Steffl & Stern 2007).…”

Limits on Pluto’s ring system from the June 12 2006 stellar occultation and implications for the New Horizons impact hazard

“…The ring systems of both Uranus and Neptune were detected by stellar occultations before they were imaged (Guinan et al 1982;Elliot et al 1977), and occultations were recently used to detect a ring system surrounding the asteroid Chariklo (Braga-Ribas et al 2014). In the Saturn system, ring occultations are frequently observed with Cassini to study structure at scales much smaller than the imaging resolution limit.…”

“…Searches for rings here or elsewhere in the system have so far detected nothing (Boissel et al 2014;McKay 2008;Steffl and Stern 2007;Pasachoff et al 2006). In this paper, we present results which improve the upper limit on the putative Plutonian rings.…”

“…4 holds. Diffraction effects cause the light curve by a small occulter to be more complex than a simple 'top hat' profile (Boissel et al 2014). Because we are sampling the data at roughly the Fresnel resolution, and the occultation depth is small, most of this structure in the wings is not visible and the occultation is essentially a dip one or two bins wide.…”