Spinning and colour properties of the active asteroid (6478) Gault
Date Issued
2020
Author(s)
Abstract
We report on accurate BVRc observations of (6478) Gault, a 5-6 km diameter inner main-belt asteroid in the Phocaea family, notable for its sporadic, comet-like ejection of dust. This curious behaviour has been mainly interpreted as reconfigurations after YORP spin-up, although merging of a contact binary system cannot be fully excluded. We collected optical observations along the 2019 March-April period, at orbital phase angles between 12° and 21°, to search for direct evidence of asteroid quick spinning rotation. A prevailing period value of 3.34 ± 0.02 h is supported by our and other photometric observations. In the YORP spin-up hypothesis, this period points to a bulk density ρ ≈ 1 g cm^{-3}. The mean colours are B - V = +0.82±0.3, V - Rc = +0.28±0.06, and B - Rc = +1.11±0.4, but we have observed a trend towards bluer colour during the April session, with about Δ(B - V) ∼ 0.35 ± 0.09 mag. This colour change can be due to asteroid rotation and support the hypothesis that there is a bluer surface under the Gault's dust.
Volume
493
Issue
1
Start page
70
Issn Identifier
0035-8711
Ads BibCode
2020MNRAS.493...70C
Rights
open.access
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