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The mysterious active asteroid Gault

Asteroid (6478) Gault is a mysterious object; although it is in the Main Belt of asteroids, this object presents a cometary activity. During 2018 and 2019 astronomers detected a tail of matter in the asteroid's motion around the Sun, most likely due to the sublimation of light elements in its composition. The phenomenon involves the particles of dust and gas that reflect sunlight.

An international team that includes researchers from MIT-US, Astronomical Institute of the Romanian Academy, Weizmann Institute of Science in Israel, Observatoire de Paris-France, Lowell Observatory, Institute for Astronomy in Hawaii, and Northern Arizona University, has monitored the asteroid and obtained spectral and photometric data of Gault, between March and April 2019. Near-infrared spectral observations were performed in late March and early April 2019 with the 3 m diameter IRTF (NASA) telescope located in Mauna Kea-Hawaii; the spectral data were corroborated with the photometric data (Figure 1) obtained with the NEEMO-T05 telescope operated by the Astronomical Institute of the Romanian Academy.

Observational data confirm that the surface of the object contains minerals rich in silicium, most likely similar to the mineralogical composition of the asteroid family (25) Phocaea. The spectral data show variations of the spectral slope, decorrelated by a possible burst in object's cometary activity. This aspect can be explained by observing a new layer, unaltered by space weather, predominantly present on the surface of the object after the initial dust layer was entrained in the tail developed by the asteroid.

These results were recently published in the prestigious Astrophysical Journal Letters.

M. Marsset, F. DeMeo, A. Sonka, et al., "Active asteroid (6478) Gault: a blue Q-type surface below the dust?” accepted in Astrophysical Journal Letters. Contacts: Adrian Sonka, Astronomical Institute of the Romanian Academy, Mirel Birlan, Paris Observatory.

Published on: Aug 04, 2019

Images used for Gault photometry were obtained in four nights of observations with the Romanian infrastructure. The asteroid is the point-like object in images that leaves behind a trail

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