Active Asteroid (6478) Gault: A Blue Q-type Surface below the Dust?

Marsset, Michaël and DeMeo, Francesca and Sonka, Adrian and Birlan, Mirel and Polishook, David and Burt, Brian and Binzel, Richard P. and Bus, Shelte J. and Thomas, Cristina (2019) Active Asteroid (6478) Gault: A Blue Q-type Surface below the Dust? The Astrophysical Journal, 882 (1). L2. ISSN 2041-8213

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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.

Item Type: Article
Subjects: AP Academic Press > Physics and Astronomy
Depositing User: Unnamed user with email support@apacademicpress.com
Date Deposited: 31 May 2023 05:49
Last Modified: 18 Oct 2024 04:14
URI: http://info.openarchivespress.com/id/eprint/1401

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