Physical Characterization of Active Asteroid (6478) Gault

Abstract

Main belt asteroid (6478) Gault has been dynamically linked with two overlapping asteroid families: Phocaea, dominated by S-type asteroids, and Tamara, dominated by low-albedo C-types. This object has recently become an interesting case for study, after images obtained in late 2018 revealed that it was active and displaying a comet-like tail. Previous authors have proposed that the most likely scenarios to explain the observed activity on Gault were rotational excitation or merger of near-contact binaries. Here we use new photometric and spectroscopic data of Gault to determine its physical and compositional properties. Lightcurves derived from the photometric data showed little variation over three nights of observations, which prevented us from determining the rotation period of the asteroid. Using WISE observations of Gault and the near-Earth Asteroid Thermal Model (NEATM) we determined that this asteroid has a diameter $<$6 km. NIR spectroscopic data obtained with the Infrared Telescope Facility (IRTF) showed a spectrum similar to that of S-complex asteroids, and a surface composition consistent with H chondrite meteorites. These results favor a compositional affinity between Gault and asteroid (25) Phocaea, and rules out a compositional link with the Tamara family. From the spectroscopic data we found no evidence of fresh material that could have been exposed during the outburst episodes.

arXiv comment9 pages, 4 figures, accepted for publication in ApJL

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Cited by in corpus (10)

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• (6478) Gault: Physical characterization of an active main-belt asteroid
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• Active asteroid (6478) Gault: a blue Q-type surface below the dust?
• Rotational Mass Shedding from Asteroid (6478) Gault
• Fragmenting Active Asteroid 331P/Gibbs
• Lifted particles from the fast spinning primary of the Near-Earth Asteroid (65803) Didymos
• Spinning and color properties of the active asteroid (6478) Gault
• Activity of (6478) Gault during January 13 - March 28, 2019
• Probabilistic modeling of asteroid diameters from Gaia DR2 errors