TY - JOUR
T1 - The cool surfaces of binary near-Earth asteroids
AU - Delbo, Marco
AU - Walsh, Kevin
AU - Mueller, Michael
AU - Harris, Alan W.
AU - Howell, Ellen S.
N1 - Funding Information:
This research was carried out while Marco Delbo’, Kevin Walsh and Michael Mueller were Henri Poincaré Fellows at the Observatoire de la Côte d’Azur. The Henri Poincaré Fellowship is funded by the CNRS-INSU, the Conseil Général des Alpes-Maritimes and the Rotary International – District 1730.
PY - 2011/3
Y1 - 2011/3
N2 - 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.
AB - 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.
KW - Asteroids
KW - Infrared observations
KW - Satellites of asteroids
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U2 - 10.1016/j.icarus.2010.12.011
DO - 10.1016/j.icarus.2010.12.011
M3 - Article
AN - SCOPUS:79952004348
VL - 212
SP - 138
EP - 148
JO - Icarus
JF - Icarus
SN - 0019-1035
IS - 1
ER -