The mutual orbit, mass, and density of the large transneptunian binary system Varda and Ilmarë

W. M. Grundy, S. B. Porter, S. D. Benecchi, H. G. Roe, K. S. Noll, C. A. Trujillo, A. Thirouin, J. A. Stansberry, E. Barker, H. F. Levison

Research output: Contribution to journalArticlepeer-review

25 Scopus citations

Abstract

From observations by the Hubble Space Telescope, Keck II Telescope, and Gemini North Telescope, we have determined the mutual orbit of the large transneptunian object (174567) Varda and its satellite Ilmarë. These two objects orbit one another in a highly inclined, circular or near-circular orbit with a period of 5.75days and a semimajor axis of 4810km. This orbit reveals the system mass to be (2.664±0.064)×1020kg, slightly greater than the mass of the second most massive main-belt asteroid (4) Vesta. The dynamical mass can in turn be combined with estimates of the surface area of the system from Herschel Space Telescope thermal observations to estimate a bulk density of 1.24-0.35+0.50g cm-3. Varda and Ilmarë both have colors similar to the combined colors of the system, B-V=0.886±0.025 and V-I=1.156±0.029.

Original languageEnglish (US)
Pages (from-to)130-138
Number of pages9
JournalIcarus
Volume257
DOIs
StatePublished - Sep 1 2015
Externally publishedYes

Keywords

  • Astrometry
  • Hubble Space Telescope observations
  • Kuiper belt
  • Satellites, general
  • Trans-neptunian objects

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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