تقرير
Spectrophotometric properties of dwarf planet Ceres from the VIR spectrometer on board the Dawn mission
| العنوان: | Spectrophotometric properties of dwarf planet Ceres from the VIR spectrometer on board the Dawn mission |
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| المؤلفون: | Ciarniello, M., De Sanctis, M. C., Ammannito, E., Raponi, A., Longobardo, A., Palomba, E., Carrozzo, F. G., Tosi, F., Li, J. -Y., Schröder, S. E., Zambon, F., Frigeri, A., Fonte, S., Giardino, M., Pieters, C. M., Raymond, C. A., Russell, C. T. |
| المصدر: | A&A 598, A130 (2017) |
| سنة النشر: | 2016 |
| المجموعة: | Astrophysics |
| مصطلحات موضوعية: | Astrophysics - Earth and Planetary Astrophysics |
| الوصف: | We study the spectrophotometric properties of dwarf planet Ceres in the VIS-IR spectral range by means of hyper-spectral images acquired by the VIR imaging spectrometer on board the NASA Dawn mission. Disk-resolved observations with a phase angle within the $7^{\circ}<\alpha<132^{\circ}$ interval were used to characterize Ceres' phase curve in the 0.465-4.05 $\mu$m spectral range. Hapke's model was applied to perform the photometric correction of the dataset, allowing us to produce albedo and color maps of the surface. The $V$-band magnitude phase function of Ceres was fitted with both the classical linear model and H-G formalism. The single-scattering albedo and the asymmetry parameter at 0.55$\mu$m are $w=0.14\pm0.02$ and $\xi=-0.11\pm0.08$, respectively (two-lobe Henyey-Greenstein phase function); the modeled geometric albedo is $0.094\pm0.007$; the roughness parameter is $\bar{\theta}=29^{\circ}\pm6^{\circ}$. Albedo maps indicate small variability on a global scale with an average reflectance of $0.034 \pm 0.003$. Isolated areas such as the Occator bright spots, Haulani, and Oxo show an albedo much higher than average. We measure a significant spectral phase reddening, and the average spectral slope of Ceres' surface after photometric correction is $1.1\%k\AA^{-1}$ and $0.85\%k\AA^{-1}$ at VIS and IR wavelengths, respectively. Broadband color indices are $V-R=0.38\pm0.01$ and $R-I=0.33\pm0.02$. H-G modeling of the $V$-band magnitude phase curve for $\alpha<30^{\circ}$ gives $H=3.14\pm0.04$ and $G=0.10\pm0.04$, while the classical linear model provides $V(1,1,0^{\circ})=3.48\pm0.03$ and $\beta=0.036\pm0.002$. The comparison with spectrophotometric properties of other minor bodies indicates that Ceres has a less back-scattering phase function and a slightly higher albedo than comets and C-type objects. However, the latter represents the closest match in the usual asteroid taxonomy. Comment: 14 pages, 20 figures, published online on Astronomy and Astrophysics on 13 February 2017. Revised to reflect minor changes in text and figures made in proofs, updated value of V-R and R-I |
| نوع الوثيقة: | Working Paper |
| DOI: | 10.1051/0004-6361/201629490 |
| URL الوصول: | http://arxiv.org/abs/1608.04643 |
| رقم الأكسشن: | edsarx.1608.04643 |
| قاعدة البيانات: | arXiv |
| DOI: | 10.1051/0004-6361/201629490 |
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