Spitzer Albedos of Near-Earth Objects. (arXiv:1906.07284v1 [astro-ph.EP])
<a href="http://arxiv.org/find/astro-ph/1/au:+Gustafsson_A/0/1/0/all/0/1">Annika Gustafsson</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Trilling_D/0/1/0/all/0/1">David E. Trilling</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Mommert_M/0/1/0/all/0/1">Michael Mommert</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+McNeill_A/0/1/0/all/0/1">Andrew McNeill</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hora_J/0/1/0/all/0/1">Joseph L. Hora</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Smith_H/0/1/0/all/0/1">Howard A. Smith</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hellmich_S/0/1/0/all/0/1">Stephan Hellmich</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Mottola_S/0/1/0/all/0/1">Stefano Mottola</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Harris_A/0/1/0/all/0/1">Alan W. Harris</a>
Thermal infrared observations are the most effective way to measure asteroid
diameter and albedo for a large number of near-Earth objects. Major surveys
like NEOWISE, NEOSurvey, ExploreNEOs, and NEOLegacy find a small fraction of
high albedo objects that do not have clear analogs in the current meteorite
population. About 8% of Spitzer-observed near-Earth objects have nominal albedo
solutions greater than 0.5. This may be a result of lightcurve variability
leading to an incorrect estimate of diameter or inaccurate absolute visual
magnitudes. For a sample of 23 high albedo NEOs we do not find that their
shapes are significantly different from the McNeill et al. (2019) near-Earth
object shape distribution. We performed a Monte Carlo analysis on 1505
near-Earth objects observed by Spitzer, sampling the visible and thermal fluxes
of all targets to determine the likelihood of obtaining a high albedo
erroneously. Implementing the McNeill shape distribution for near-Earth
objects, we provide an upper-limit on the geometric albedo of 0.5+/-0.1 for the
near-Earth population.
Thermal infrared observations are the most effective way to measure asteroid
diameter and albedo for a large number of near-Earth objects. Major surveys
like NEOWISE, NEOSurvey, ExploreNEOs, and NEOLegacy find a small fraction of
high albedo objects that do not have clear analogs in the current meteorite
population. About 8% of Spitzer-observed near-Earth objects have nominal albedo
solutions greater than 0.5. This may be a result of lightcurve variability
leading to an incorrect estimate of diameter or inaccurate absolute visual
magnitudes. For a sample of 23 high albedo NEOs we do not find that their
shapes are significantly different from the McNeill et al. (2019) near-Earth
object shape distribution. We performed a Monte Carlo analysis on 1505
near-Earth objects observed by Spitzer, sampling the visible and thermal fluxes
of all targets to determine the likelihood of obtaining a high albedo
erroneously. Implementing the McNeill shape distribution for near-Earth
objects, we provide an upper-limit on the geometric albedo of 0.5+/-0.1 for the
near-Earth population.
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