Paper No. 166-6
TOSI, Federico1, CARROZZO, Filippo Giacomo
2, ZAMBON, Francesca
1, CIARNIELLO, Mauro
1, COMBE, Jean-Philippe
3, DE SANCTIS, Maria Cristina
1, HOFFMANN, Martin
4, LONGOBARDO, Andrea
5, NATHUES, Andreas
6, RAPONI, Andrea
1, AMMANNITO, Eleonora
7, KROHN, Katrin
8, MCFADDEN, Lucy
9, PIETERS, Carle M.
10, STEPHAN, Katrin
11, RUSSELL, Christopher T.
12 and RAYMOND, Carol A.
13, (1)INAF - Istituto Nazionale di Astrofisica, IAPS - Istituto di Astrofisica e Planetologia Spaziali, Via del Fosso del Cavaliere, 100, Rome, I-00133, Italy, (2)INAF - Istituto Nazionale di Astrofisica, IAPS - Istituto di Astrofisica e Planetologia Spaziali, Via del Fosso del Cavaliere, 100, Rome, I-00133, (3)Bear Fight Institute, P.O. Box 667, 22 Fiddler's Rd, Winthrop, WA 98862, (4)Max Planck Institute for Solar System Research, Justus-von-Liebig-Weg 3, Goettingen, 37077, Germany, (5)IAPS - Istituto di Astrofisica e Planetologia Spaziali, INAF - Istituto Nazionale di Astrofisica, Via del Fosso del Cavaliere, 100, Rome, I-00133, Italy, (6)Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig-Weg 3, Goettingen, 37077, Germany, (7)Institute of Geophysics and Planetary Physics, University of California, Los Angeles, CA, (8)Institute of Planetary Research, German Aerospace Center (DLR), Rutherfordstr. 2, Berlin, 12489, Germany, (9)NASA Goddard Space Flight Center, Greenbelt, MD 20771, (10)Department of Geological Sciences, Brown University, 324 Brook Street, Providence, RI 02912, (11)German Aerospace Center, Institute of Planetary Research, Rutherfordstrasse 2, Berlin, 12489, Germany, (12)Earth Planetary and Space Sciences, University of California, Los Angeles, Los Angeles, CA 90095-1567, (13)Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, federico.tosi@iaps.inaf.it
Quadrangle Ac-H-6 ‘Haulani’ is one of five quadrangles that cover the equatorial region of the dwarf planet Ceres. This quadrangle is notable for the high albedo (bright) ejecta that extend around crater Haulani, which gives the name to the quadrangle. In Dawn’s Framing Camera (FC) color-ratio composite images, crater Haulani is clearly distinct compared to surrounding terrains. Haulani’s bright material displays a very small or even negative ("blue") spectral slope in the range from the visible to the near infrared, which is a peculiar occurrence compared to rest of the quadrangle and more generally to the average surface of Ceres.
Hyperspectral images returned by the Visible and InfraRed (VIR) mapping spectrometer onboard Dawn enabled a careful mineralogical analysis of the Haulani quadrangle. In the High-Altitude Mapping Orbit HAMO phase, yielding an average pixel resolution of ~0.38 km, VIR obtained nearly global coverage of quadrangle Ac-H-6. Based on this dataset, crater Haulani also stands out compared to the rest of the quadrangle. The spectral features centered at 2.7 and 3.06 µm, respectively indicative of the presence of hydrous minerals and ammoniated phyllosilicates, show a decrease of band depth in the floor and in Haulani’s bright ejecta, corresponding to the blue spectral slope.
Similar, but less prominent, spectral behavior, is observed in other small craters found within this quadrangle.
Acknowledgements
This work is supported by the Italian Space Agency (ASI). VIR was funded and coordinated by the Italian Space Agency, with the scientific leadership of the Institute for Space Astrophysics and Planetology, Italian National Institute for Astrophysics, Italy. Support of the Dawn Science, Instrument, and Operation Teams is gratefully acknowledged.
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