Rotational Variability of Asteroid 490 Veritas in the Near-Infrared

Document Type

Conference Proceeding

Publication Date

9-2009

Publication Title

American Astronomical Society, Department of Planetary Sciences

Abstract

We present rotationally resolved spectra of asteroid 490 Veritas in the near-infrared (NIR) that show interesting differences. Dynamical arguments indicate that 490 Veritas is the main fragment of a recent (8.3 My) asteroidal break-up. We obtained NIR spectra (0.8-2.4 microns) on UT May 11, 2008, using the SpeX instrument on NASA's Infrared Telescope Facility (IRTF) on Mauna Kea, Hawaii. Since published visible spectra of 490 Veritas show some variability, we decided to observe its NIR spectrum at four distinct rotational phases. Veritas's rotational light curve has a period of 7.93 hours with amplitudes ranging from 0.3 to 0.5 magnitudes in the visible. We define the time of our first observation as zero rotational phase and our subsequent observations are at 0.29, 0.52, and 0.70. Our reflectance spectra show a range of slopes. To characterize these slope differences, we normalized each spectrum to 1.0 reflectance at 1.25 microns and measured the reflectance at 2.2 microns. The values obtained are reflectances of 0.99, 1.02, 0.98, and 0.93 at rotational phase 0.00, 0.29, 0.52, and 0.70, respectively. The uncertainty in each reflectance value is ± 3%. In this work, we consider possible causes of this variability, including heterogeneity of the parent body and/or space weathering i.e., from different surfaces having experienced various exposure ages.

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