Discovered by Annibale de Gasparis Alternative names none Orbital period 1,365 days Orbits Sun Discoverer Annibale de Gasparis | Discovery date September 19, 1852 Aphelion 411.911 Gm (2.753 AU) Discovered 19 September 1852 Spectral type S-type asteroid Named after Marseille | |
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Pronunciation /məˈseɪliə/ mə-SAY-lee-ə Minor planet category Main belt (Massalia family) Similar Annibale de Gasparis discoveries, Other celestial objects | ||
Asteroid 20 massalia in virgo
20 Massalia is a large and fairly bright main-belt asteroid. It is also the largest member of the Massalia family of asteroids. Its name is the Greek name for Marseille, the city from which one of the two independent co-discovers, Jean Chacornac, first sighted it.
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Characteristics
Massalia is an S-type asteroid. It orbits at very low inclination in the intermediate main belt, and is by far the largest asteroid in the Massalia family. The remaining family members are fragments ejected by a cratering event on Massalia.
Massalia has an above-average density for S-type asteroids, similar to the density of silicate rocks. As such, it appears to be a solid un-fractured body, a rarity among asteroids of its size. Apart from the few largest bodies over 400 km in diameter, such as 1 Ceres and 4 Vesta, most asteroids appear to have been significantly fractured, or are even rubble piles. In 1998, Bange estimated Massalia to have a mass of 5.2×1018 kg assuming that 4 Vesta has 1.35×10−10 solar mass. The mass of Massalia is dependent on the mass of 4 Vesta and perturbation of 44 Nysa.
Lightcurve analysis indicates that Massalia's pole points towards either ecliptic coordinates (β, λ) = (45°, 10°) or (β, λ) = (45°, 190°) with a 10° uncertainty. This gives an axial tilt of 45°in both cases. The shape reconstruction from lightcurves has been described as quite spherical with large planar, nonconvex parts of the surface.
In 1988 a search for satellites or dust orbiting this asteroid was performed using the UH88 telescope at the Mauna Kea Observatories, but the effort came up empty.
Discovery
Massalia was discovered by A. de Gasparis on September 19, 1852 in Naples, and also found independently the next night by J. Chacornac in Marseilles. It was Chacornac's discovery that was announced first. In the nineteenth century the variant spelling Massilia was often used. Asteroids discovered prior to Massalia were assigned iconic symbols, like the ones traditionally used to designate the planets. However, astronomers had begun to phase out this practice with the discovery of 16 Psyche in March 1852, and 20 Massalia (being the first object in the Solar System with a non-mythological name) was the first asteroid that was not assigned an iconic symbol.