809 Lundia

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809 Lundia
Discovery
Discoverer Max Wolf
Discovery date August 11, 1915
Alternate
designations
1915 XP; 1936 VC
Category Main belt
Orbital elements
Epoch November 26, 2005 (JD 2453700.5)
Eccentricity (e) 0.193
Semi-major axis (a) 341.556 Gm (2.283 AU)
Perihelion (q) 275.743 Gm (1.843 AU)
Aphelion (Q) 407.368 Gm (2.723 AU)
Orbital period (P) 1260.094 d (3.45 a)
Mean orbital speed 19.53 km/s
Inclination (i) 7.143°
Longitude of the
ascending node
(Ω)
154.685°
Argument of
perihelion
(ω)
196.321°
Mean anomaly (M) 42.298°
Physical characteristics
Dimensions 7–10 km (estimate) (for each component)
Mass 0.2–2×1015 each (estimate)
Density unknown
Surface gravity 0.001–0.003 m/s² (estimate)
Escape velocity 0.003–0.005 km/s (estimate)
Rotation period unknown
Spectral class V
Absolute magnitude 11.8
Albedo (geometric) unknown
Mean surface
temperature
165-180 K
max: 260-280 K

809 Lundia is a small, binary, V-type asteroid[1] orbiting in the Flora family in the Main Belt. It is named after Lund Observatory, Sweden.

The V-type spectrum says that it is not genetically related to the Flora family, but rather is probably a piece (actually two pieces) blown off the surface of nearby 4 Vesta by a big impact in the past. Its orbit is too far from Vesta for it to actually be a member of the Vesta family It is not clear how it came at an orbit so far from Vesta, but other examples of V-type asteroids fairly far from their parent body are known. A mechanism of interplay between the Yarkovsky effect and nonlinear secular resonances (mainly involving Jupiter and Saturn) has been suggested.[2]

Binary[change | change source]

A moon, designated S/2005 (809) 1, was seen based on lightcurve sightings in 2005. In fact, the size of the two bodies appear to be close in size, because during mutual occultations the brightness drops by a similar amount independently of which body is hidden.[3] Assuming an albedo similar to 4 Vesta (around 0.4), suggests that the bodies are about 7 km across. It takes 15.4 hours to orbit each other[3], which says that the binary is very close — the separation being of the order of 10-20 km, if normal asteroid albedo and density values are assumed.

References[change | change source]

  1. M. Florczak, D. Lazarro, & R. Duffard (2002). "Discovering New V-Type Asteroids in the Vicinity of 4 Vesta". Icarus 159: 178.
  2. V. Carruba et al. (2005). "On the V-type asteroids outside the Vesta family". Astronomy & Astrophysics 441: 819.
  3. 3.0 3.1 Poznań observatory [1] (Lightcurve showing signature of the binary)

Other websites[change | change source]