809 Lundia
Main-belt asteroid binary
From Wikipedia, the free encyclopedia
809 Lundia is a small, binary, V-type asteroid[3] orbiting within the Flora family in the main belt. It is named after Lund Observatory, Sweden.
Asteroid 809 Lundia (apparent magnitude 16.6) near a mag 15.6 star | |
| Discovery | |
|---|---|
| Discovered by | Max Wolf |
| Discovery date | 11 August 1915 |
| Designations | |
| (809) Lundia | |
| Pronunciation | /ˈlʌndiə/ |
Named after | Lund Observatory |
| 1915 XP; 1936 VC | |
| Main belt | |
| Orbital characteristics[1] | |
| Epoch 31 July 2016 (JD 2457600.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 100.48 yr (36700 d) |
| Aphelion | 2.72316 AU (407.379 Gm) |
| Perihelion | 1.84193 AU (275.549 Gm) |
| 2.28254 AU (341.463 Gm) | |
| Eccentricity | 0.19304 |
| 3.45 yr (1259.6 d) | |
| 76.7867° | |
| 0° 17m 8.912s / day | |
| Inclination | 7.14911° |
| 154.580° | |
| 196.162° | |
| Physical characteristics | |
| Dimensions | 10.26 ± 0.07 km[2] |
| Mass | (9.27 ± 3.09) × 1014 kg[2] |
Mean density | 1.64 ± 0.10 g/cm3[2] |
| 15.4142 h (0.64226 d) | |
| V | |
| 12.2 | |
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.[4]
Binary system
Lightcurve observations in 2005 revealed that Lundia is a binary system of two similarly sized objects orbiting their common centre of gravity. The satellite remains undesignated.[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.[5] Due to the similar size of the primary and secondary the Minor Planet Center lists this as a binary companion.[6]
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,[5] 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.
