Ellipsoidal geometry in asteroid thermal models: The standard radiometric model

Robert Hamilton Brown

Research output: Contribution to journalArticlepeer-review

29 Scopus citations


This paper reports results of the incorporation of ellipsoidal geometry into the standard radiometric model for asteroids. For small departures from spherical shape the standard model using spherical geometry predicts fluxes in good agreement with ellipsoidal models. Large departures from spherical shape, however, can produce substantial differences in the calculated flux depending on the subsolar temperature and the wavelength of interest. The results derived here suggest that radiometric measurements of highly nonspherical, low-obliquity asteroids interpreted with spherical models result in systematically smaller diameter and higher albedos. In addition, non-spherical shape can also result in a systematic difference in the diameter of a particular asteroid derived from separate 10- and 20-μm flux measurements interpreted with spherical models. Thermal-infrared diurnal lightcurves calculated for ellipsoids have amplitudes that depend on wavelength as well as projected area, and phase curves calculated for ellipsoids are indistinguishable from those calculated for spheres.

Original languageEnglish (US)
Pages (from-to)53-63
Number of pages11
Issue number1
StatePublished - Oct 1985

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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