The cool surfaces of binary near-Earth asteroids

Marco Delbo, Kevin Walsh, Michael Mueller, Alan W. Harris, Ellen S. Howell

Research output: Contribution to journalArticlepeer-review

26 Scopus citations

Abstract

Here we show results from thermal-infrared observations of km-sized binary near-Earth asteroids (NEAs). We combine previously published thermal properties for NEAs with newly derived values for three binary NEAs. The η value derived from the near-Earth asteroid thermal model (NEATM) for each object is then used to estimate an average thermal inertia for the population of binary NEAs and compared against similar estimates for the population of non-binaries. We find that these objects have, in general, surface temperatures cooler than the average values for non-binary NEAs as suggested by elevated η values. We discuss how this may be evidence of higher-than-average surface thermal inertia. This latter physical parameter is a sensitive indicator of the presence or absence of regolith: bodies covered with fine regolith, such as the Earth's moon, have low thermal inertia, whereas a surface with little or no regolith displays high thermal inertia. Our results are suggestive of a binary formation mechanism capable of altering surface properties, possibly removing regolith: an obvious candidate is the YORP effect. We present also newly determined sizes and geometric visible albedos derived from thermal-infrared observations of three binary NEAs: (5381) Sekhmet, (153591) 2001 SN263, and (164121) 2003 YT1. The diameters of these asteroids are 1.41±0.21km, 1.56±0.31km, and 2.63±0.40km, respectively. Their albedos are 0.23±0.13, 0.24±0.16, and 0.048±0.015, respectively.

Original languageEnglish (US)
Pages (from-to)138-148
Number of pages11
JournalIcarus
Volume212
Issue number1
DOIs
StatePublished - Mar 2011
Externally publishedYes

Keywords

  • Asteroids
  • Infrared observations
  • Satellites of asteroids

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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