| Minorplanet: | yes |
| Background: |
|
| 809 Lundia | |
| Discovered: | 11 August 1915 |
| Mpc Name: | (809) Lundia |
| Alt Names: | 1915 XP; 1936 VC |
| Epoch: | 31 July 2016 (JD 2457600.5) |
| Semimajor: | 2.28254AU |
| Perihelion: | 1.84193AU |
| Aphelion: | 2.72316abbr=onNaNabbr=on |
| Eccentricity: | 0.19304 |
| Period: | 3.45 yr (1259.6 d) |
| Inclination: | 7.14911° |
| Asc Node: | 154.580° |
| Arg Peri: | 196.162° |
| Dimensions: | 10.26 ± 0.07 km |
| Density: | 1.64 ± 0.10 g/cm3 |
| Rotation: | 15.4142abbr=onNaNabbr=on |
| Abs Magnitude: | 12.2 |
| Mean Motion: | / day |
| Observation Arc: | 100.48 yr (36700 d) |
| Uncertainty: | 0 |
809 Lundia is a small, binary, V-type asteroid[1] orbiting within the Flora family in the main belt. It is named after Lund Observatory, Sweden.
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.[2]
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.[3] Due to the similar size of the primary and secondary the Minor Planet Center lists this as a binary companion.[4]
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.