Alternative names 1915 XP; 1936 VC Observation arc 100.48 yr (36700 d) Orbits Sun Discoverer Max Wolf Moon S/2005 (809) 1 | Discovery date 11 August 1915 Minor planet category Main belt Discovered 11 August 1915 | |
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Aphelion 2.72316 AU (407.379 Gm) Similar 528 Rezia, Asteroid belt, 889 Erynia, 540 Rosamunde, 509 Iolanda | ||
809 Lundia is a small, binary, V-type asteroid orbiting within the Flora family in the main belt. It is named after Lund Observatory, Sweden.
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Characteristics
Lundia orbits within the Flora family. However, its V-type spectrum indicates that it is not genetically related to the Flora family, but rather is probably a fragment (two fragments, if its moon is included) ejected from the surface of 4 Vesta by a large impact in the past. Its orbit lies too far from Vesta for it to actually be a member of the Vesta family. It is not clear how it arrived at an orbit so far from Vesta, but other examples of V-type asteroids orbiting fairly far from their parent body are known. A mechanism of interplay between the Yarkovsky effect and nonlinear secular resonances (primarily involving Jupiter and Saturn) has been proposed.
Binary system
Lightcurve observations in 2005 revealed that Lundia is a binary system of two similarly sized objects orbiting their common centre of gravity. "Lundia" now refers to one of the objects, the other being provisionally designated S/2005 (809) 1. The similarity of size between the two components is suspected because during mutual occultations the brightness drops by a similar amount independently of which component is hidden. Due to the similar size of the primary and secondary the Minor Planet Center lists this as a binary companion.
Assuming an albedo similar to 4 Vesta (around 0.4) suggests that the components are about 7 km across. They orbit each other in a period of 15.4 hours, which roughly indicates that the separation between them is very close: to the order of 10–20 km if typical asteroid albedo and density values are assumed.