| Discovery[1] | |
|---|---|
| Discovered by | G. Neujmin |
| Discovery site | Simeiz Obs. |
| Discovery date | 24 June 1914 |
| Designations | |
| (789) Lena | |
| Pronunciation | /ˈleɪnə/[2] |
Named after | Elena Neujmina (discoverer's family)[3] |
| 1914 UU · 1970 CE | |
| main-belt · (middle)[4] | |
| Orbital characteristics[1] | |
| Epoch 16 February 2017 (JD 2457800.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 81.69 yr (29,837 days) |
| Aphelion | 3.0817AU |
| Perihelion | 2.2907 AU |
| 2.6862 AU | |
| Eccentricity | 0.1472 |
| 4.40yr (1,608 days) | |
| 110.02° | |
| 0° 13m 26.04s / day | |
| Inclination | 10.781° |
| 232.62° | |
| 44.006° | |
| Physical characteristics | |
| Dimensions | 20.56±0.34 km[5] 22.483±0.306[6] 23.871±0.162 km[7] 24.18 km(calculated)[4] |
| 5.84239±0.00001h[8] 5.848±0.001 h[9] 5.85±0.05 h[10] 22 h[11] | |
| 0.10(assumed)[4] 0.1373±0.0147[7] 0.153±0.028[6] 0.186±0.007[5] | |
| SMASS =X[1] · M[7] · X[4] | |
| 10.47±0.60[12] · 10.9[5][7] · 11.2[1][4] | |
789 Lena, provisional designation1914 UU, is a metallicasteroid from the middle region of theasteroid belt, approximately 24 kilometers in diameter. It was discovered on 24 June 1914, by Soviet–Russian astronomerGrigory Neujmin atSimeiz Observatory on the Crimean peninsula, and named after the discoverer's mother.[13]
Lena orbits the Sun in themiddle main-belt at a distance of 2.3–3.1 AU once every 4 years and 5 months (1,608 days). Its orbit has aneccentricity of 0.15 and aninclination of 11° with respect to theecliptic.[1]Lena'sobservation arc begins with its first used observation made atYerkes Observatory in 1935, or 21 years after its official discovery observation at Simeiz.[13]
Although its orbital elements resemble those of the asteroids in theEunomia family, true members of this family have aS-type composition, so it is almost certainly an unrelated interloper.[citation needed]
In theSMASS taxonomy,Lena is anX-type asteroid. It has also been characterized as a metallicM-type asteroid by NASA'sWide-field Infrared Survey Explorer (WISE).[7]
In 1993, a rotationallightcurve which was later proven incorrect, was obtained from photometric observations at theFélix Aguilar Observatory, Argentina. It gave an unusual lightcurve, indicating a very irregular shape and/or a relatively longrotation period of 22 hours with an exceptionally high amplitude of 1.5 inmagnitude (U=0).[11]
In August and September 2007, two reliable lightcurves were obtained by Italian astronomerSilvano Casulli and by members at the U.S.Oakley Observatory. Lightcurve analysis gave a period of5.848±0.001 and5.85±0.05 hours, with a brightness variation of 0.50 and of 0.40 magnitude, respectively (U=3/2+).[a][9][10]
According to the space-based surveys carried out by the JapaneseAkari satellite and theNEOWISE mission of the WISE telescope,Lena measures between 20.6 and 23.9 kilometers in diameter, and its surface has analbedo of 0.137–0.186.[5][6][7] TheCollaborative Asteroid Lightcurve Link assumes a much lower albedo of 0.10 and calculates a diameter of 24.2 kilometer, as the lower the albedo (reflectivity), the larger a body's diameter, at a constantabsolute magnitude (brightness).[4]
Thisminor planet was named in honor of Elena ("Lena") Petrovna Neujmina (1860–1942), mother of the discovering astronomerGrigory Neujmin.[3]
