Active Asteroid (6478) Gault: A Blue Q-type Surface below the Dust?
Name
1907.10077.pdf
Description
Accepted version
Size
2.69 MB
Format
Unknown
Checksum (MD5)
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Author(s)
Marsset, Michaël
DeMeo, Francesca E
Sonka, Adrian
Birlan, Mirel
Polishook, David
Burt, Brian
Binzel, Richard P
Bus, Shelte J.
Thomas, Cristina
Date Issued
August 2019
Journal
Astrophysical Journal Letters
Publisher
American Astronomical Society
Citation
Marsset, Michaël"Active Asteroid (6478) Gault: A Blue Q-type Surface below the Dust?." Astrophysical Journal Letters, 882, 1 (August 2019): L2. © 2019 The American Astronomical Society
Version
Author's final manuscript
Abstract
We present near-infrared spectroscopy of the sporadically active asteroid (6478)Gault collected on the 3 m NASA/Infrared Telescope Facility observatory in late 2019 March/early April. Long-exposure imaging with the 0.5 m Near Earth Environment Monitoring T05 telescope and previously published data simultaneously monitored the asteroid activity, providing context for our measurements. We confirm that Gault is a silicate-rich (Q- or S-type) object likely linked to the (25)Phocaea collisional family. The asteroid exhibits substantial spectral variability over the 0.75-2.45 μm wavelength range, from unusual blue (s′=-13.5 1.1% μm-1) to typical red (s′=+9.1 1.2% μm-1) spectral slope, that does not seem to correlate with activity. Spectral comparisons with samples of ordinary chondrite meteorites suggest that the blue color relates to the partial loss of the asteroid dust regolith, exposing a fresh, dust-free material at its surface. The existence of asteroids rotating close to rotational break-up limit and having similar spectral properties as Gault further supports this interpretation. Future spectroscopic observations of Gault, when the tails dissipate, will help further testing of our proposed hypothesis.
MIT Department
Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences
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Persistent DSpace Link
DOI of Published Version
https://doi.org/10.3847/2041-8213/ab32ee
