809 Lundia

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809 Lundia
Asteroid 809 Lundia (apparent magnitude 16.6) near a mag 15.6 star.
Discovered by Max Wolf
Discovery date August 11, 1915
Named after
Lund Observatory
1915 XP; 1936 VC
Minor planet category Main belt
Orbital characteristics
Epoch November 26, 2005 (JD 2453700.5)
Aphelion 407.368 Gm (2.723 AU)
Perihelion 275.743 Gm (1.843 AU)
341.556 Gm (2.283 AU)
Eccentricity 0.193
1260.094 d (3.45 a)
19.53 km/s
Inclination 7.143°
Physical characteristics
Dimensions 10.26 ± 0.07[1] km
Mass (9.27 ± 3.09) × 1014[1] kg
Mean density
1.64 ± 0.10[1] g/cm3
0.001–0.003 m/s² (estimate)
0.003–0.005 km/s (estimate)
Temperature 165-180 K
max: 260-280 K
Spectral type

809 Lundia is a small, binary, V-type asteroid[2] 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 one includes its moon) 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.[3]

Binary system[edit]

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.[4] Due to the similar size of the primary and secondary the Minor Planet Center lists this as a binary companion.[5]

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,[4] 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.


  1. ^ a b c Carry, B. (December 2012), Density of asteroids, Planetary and Space Science 73: 98-118, arXiv:1203.4336, Bibcode:2012P&SS...73...98C, doi:10.1016/j.pss.2012.03.009.  See Table 1.
  2. ^ M. Florczak, D. Lazarro, & R. Duffard (2002). "Discovering New V-Type Asteroids in the Vicinity of 4 Vesta". Icarus 159: 178–182. Bibcode:2002Icar..159..178F. doi:10.1006/icar.2002.6913. 
  3. ^ V. Carruba et al. (2005). "On the V-type asteroids outside the Vesta family". Astronomy & Astrophysics 441 (2): 819–829. arXiv:astro-ph/0506656. Bibcode:2005A&A...441..819C. doi:10.1051/0004-6361:20053355. 
  4. ^ a b Poznań observatory [1] (Lightcurve showing signature of the binary)
  5. ^ "Satellites and Companions of Minor Planets". IAU / Central Bureau for Astronomical Telegrams. Retrieved 2011-07-03. 

External links[edit]