 | |
| Discovery | |
|---|---|
| Discovered by | J. Chacornac |
| Discovery date | 8 February 1856 |
| Designations | |
| (39) Laetitia | |
| Pronunciation | /lɛˈtɪʃiə/[1] |
Named after | Laetitia |
| Main belt | |
| Orbital characteristics[2] | |
| Epoch 31 December 2006 (JD 2454100.5) | |
| Aphelion | 461.503 Gm (3.085 AU) |
| Perihelion | 366.877 Gm (2.452 AU) |
| 414.190 Gm (2.769 AU) | |
| Eccentricity | 0.114 |
| 1,682.713 d (4.61 a) | |
| 58.261° | |
| Inclination | 10.383° |
| 157.168° | |
| 209.560° | |
| Physical characteristics | |
| Dimensions | |
| Mass | (4.72±1.14)×1018 kg[4] |
Meandensity | 2.47±0.63 g/cm3[4] |
| 0.2141 d (5.138 h)[2][5] | |
| 0.287 (geometric)[2][6] | |
| S[2] | |
| 8.97[7] to 12.18 | |
| 6.1[2] | |
| 0.142″–0.051″ | |
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39 Laetitia is a largemain-beltasteroid that was discovered by French astronomerJean Chacornac on 9 February 1856[8] and named afterLaetitia, a minorRoman goddess ofgaiety. The spectrum matches anS-type, indicating a stony (silicate) composition. It is orbiting theSun with a period of 4.61 years and is spinning on its axis once every 5.1 hours.
Photometric observations of this asteroid gathered between 1968 and 1974 were used to build alight curve that provided shape and rotation information. It has the general shape of an elongated triaxialellipsoid with ratios between the lengths of the axes equal to 15:9:5. Major surface features are on a scale of 10 km and the surface color does not vary significantly across the surface. In theecliptic coordinate system, the pole of rotation is estimated to be oriented to the coordinates (λ0, β0) = (121°±10°,+37°±10°).[9]
In 1988 a search for satellites or dust orbiting this asteroid was performed using theUH88 telescope at theMauna Kea Observatories, but the effort came up empty.[10] Photometric observations collected during 2006–08 were used to measure time variations of the asteroid light curve. This data suggests that the asteroid may have a complex shape or it could be abinary asteroid system.[11] Observations of anoccultation on 21 March 1998, produced severalchords indicating an ellipsoidal cross-section of219 km × 142 km.[3]
