Bibcode
DOI
Fernández, Y. R.; Campins, H.; Kassis, M.; Hergenrother, C. W.; Binzel, R. P.; Licandro, J.; Hora, J. L.; Adams, J. D.
Referencia bibliográfica
The Astronomical Journal, Volume 132, Issue 3, pp. 1354-1360.
Fecha de publicación:
9
2006
Número de citas
20
Número de citas referidas
19
Descripción
We present an analysis of thermal emission from comet 162P/Siding Spring
(P/2004 TU12) measured during its discovery apparition in
2004 December. The comet showed no dust coma at this time, so we have
sampled emission from the comet's nucleus. Observations using the
Mid-Infrared Spectrometer and Imager (MIRSI) were performed at NASA's
Infrared Telescope Facility, where the peak of the comet's spectral
energy distribution was observed between 8 and 25 μm. In combination
with the three near-IR spectra presented by Campins and coworkers (in
the companion to this paper) that show the Wien-law tail of the thermal
emission, the data provide powerful constraints on surface properties of
the nucleus. We find that the nucleus's effective radius is 6.0+/-0.8
km. This is one of the largest radii known among Jupiter-family comets,
which is unusual considering that the comet was discovered only
recently. Its geometric albedo is 0.059+/-0.023 in the H band,
0.037+/-0.014 in the R band, and 0.034+/-0.013 in the V band. We also
find that the nucleus of 162P has little IR beaming, and this implies
that the nucleus has low thermal inertia. Including all near-IR spectra
yields a beaming parameter η of 1.01+/-0.20. This result is in
agreement with others showing that cometary nuclei have low thermal
inertia and little IR beaming. If confirmed for many nuclei, the
interpretation of radiometry may not be as problematic as feared.