Phase reddening on near-Earth asteroids: Implications for mineralogical analysis, space weathering and taxonomic classification

By Juan A. Sánchez, Vishnu Reddy, Andreas Nathues, Edward A. Cloutis, Paul Mann, Harald Hiesinger. 2012

176 citations recorded by the source corpus.

Abstract Phase reddening is an effect that produces an increase of the spectral slope and variations in the strength of the absorption bands as the phase angle increases. In order to understand its effect on spectroscopic observations of asteroids, we have analyzed the visible and near-infrared spectra (0.45–2.5 μm) of 12 near-Earth asteroids observed at different phase angles. All these asteroids are classified as either S-complex or Q-type asteroids. In addition, we have acquired laboratory spectra of three different types of ordinary chondrites at phase angles ranging from 13° to 120°. We have found that both, asteroid and meteorite spectra show an increase in band depths with increasing phase angle. In the case of the asteroids the Band I depth increases in the range of ∼2° g g g > 30°. Variations in band centers and band area ratio (BAR) values were also found, however they seems to have no significant impact on the mineralogical analysis. Our study showed that the increase in spectral slope caused by phase reddening is comparable to certain degree of space weathering. In particular, an increase in phase angle in the range of 30–120° will produce a reddening of the reflectance spectra equivalent to exposure times of ∼0.1 × 10 6 –1.3 × 10 6 years at about 1 AU from the Sun. This increase in spectral slope due to phase reddening is also comparable to the effects caused by the addition of different fractions of SMFe. Furthermore, we found that under some circumstances phase reddening could lead to an ambiguous taxonomic classification of asteroids.

Subfields: Astronomy and Astrophysics, Geophysics

View Paper: https://www.semanticscholar.org/paper/378df5aabd6b0cd7dd8b1ae17cbabc1bd744e61c

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Citations in the corpus

Properties of rubble-pile asteroid (101955) Bennu from OSIRIS-REx imaging and thermal analysis (2019, background): “1b), as has been observed on several other asteroids [39,40].”
Mineralogies and source regions of near-Earth asteroids (2013, methodology): “Temperature corrections from this study are identical to those from Sanchez et al. (2012), as both sets of corrections were calibrated using ordinary chondrite data from Moroz et al. (2000).”
Compositional distributions and evolutionary processes for the near-Earth object population: Results from the MIT-Hawaii Near-Earth Object Spectroscopic Survey (MITHNEOS) (2019, methodology): “ation (Fig. 3c), where each calculated value for spectral slope (change in normalized reflectance per micron) follows the methodology of the Bus-DeMeo taxonomy (DeMeo et al., 2009). In agreement with Sanchez et al. (2012), we find a strong correlation between spectral slope and phase angle (r = 0.94”