Extreme Asteroids in the Pan-STARRS 1 Survey

Andrew McNeill, Alan Fitzsimmons, Robert Jedicke, Pedro Lacerda, Eva Lilly, Andrew Thompson, David E. Trilling, Ernst DeMooij, Matthew J. Hooton, Christopher A. Watson

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Abstract

Using the first 18 months of the Pan-STARRS 1 survey, we have identified 33 candidate high-amplitude objects for follow-up observations and carried out observations of 22 asteroids. Four of the observed objects were found to have observed amplitude A obs ≥ 1.0 mag. We find that these high-amplitude objects are most simply explained by single rubble-pile objects with some density-dependent internal strength, allowing them to resist mass shedding even at their highly elongated shapes. Three further objects, although below the cutoff for “high amplitude,” had a combination of elongation and rotation period which also may require internal cohesive strength, depending on the density of the body. We find that none of the “high-amplitude asteroids” identified here require any unusual cohesive strengths to resist rotational fission. Three asteroids were sufficiently observed to allow for shape and spin-pole models to be determined through light curve inversion. Asteroid 45864 was determined to have retrograde rotation with spin-pole axes λ = 218° ± 10°, β = ‑82° ± 5° and asteroid 206167 was found to have best-fit spin-pole axes λ = 57° ± 5°, β = ‑67° ± 5°. An additional object not initially measured with A obs > 1.0 mag, 49257, was determined to have a shape model that does suggest a high-amplitude object. Its spin-pole axes were best fit for values λ = 112°± 6°, β = 6° ± 5°. In the course of this project, to date no large superfast rotators (P rot <2.2 hr) have been identified.
Original languageEnglish
Article number282
Number of pages19
JournalAstronomical Journal
Volume156
Issue number6
DOIs
Publication statusPublished - 28 Nov 2018

Bibliographical note

31 pages; accepted by AJ

Keywords

  • methods: observational
  • minor planets
  • asteroids: general
  • techniques: photometric

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