_Ani.png) Modelled shape ofAni from itslightcurve | |
| Discovery[1] | |
|---|---|
| Discovered by | G. Neujmin |
| Discovery site | Simeiz Obs. |
| Discovery date | 29 June 1914 |
| Designations | |
| (791) Ani | |
Named after | Historic city ofAni[2] |
| A914 MB · 1949 WH 1964 PO · 1975 XM 1914 UV | |
| main-belt[1][3] · (outer) Meliboea[4][5] · Bg[6] | |
| Orbital characteristics[3] | |
| Epoch 31 May 2020 (JD 2459000.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 104.08yr (38,017 d) |
| Aphelion | 3.7242AU |
| Perihelion | 2.5197 AU |
| 3.1219 AU | |
| Eccentricity | 0.1929 |
| 5.52 yr (2,015 d) | |
| 33.057° | |
| 0° 10m 43.32s / day | |
| Inclination | 16.381° |
| 129.81° | |
| 201.49° | |
| Physical characteristics | |
| Dimensions | 65.7 km × 103.5 km |
| 11.174±0.004 h[10] | |
791 Ani (prov. designation:A914 MBor1914 UV) is a very largeasteroid of theMeliboea family, located in the outer regions of theasteroid belt. It was discovered on 29 June 1914, by Russian astronomerGrigory Neujmin at theSimeiz Observatory on the Crimean peninsula.[1] The dark carbonaceousC-type asteroid has arotation period of 11.2 hours and measures approximately65.7 × 103.5 kilometers, with amean diameter of 100 km (62 mi). It was named after the historic Armenian city ofAni.[2]
When applying thehierarchical clustering method (HCM) to itsproper orbital elements,Ani is a member of theMeliboea family (604),[4][5] a smallfamily of carbonaceous asteroids in theouter main belt, named after its principal body,137 Meliboea.[13]: 23 However, according to another HCM-analysis byMilani andKnežević (AstDyS), it is abackground asteroid as this analysis does not recognize the Meliboea family.[6]Ani orbits the Sun in theouter asteroid belt at a distance of 2.5–3.7 AU once every 5 years and 6 months (2,015 days;semi-major axis of 3.12 AU). Its orbit has aneccentricity of 0.19 and aninclination of 16° with respect to theecliptic.[3] The body'sobservation arc begins atAlgiers Observatory in North Africa on 6 December 1915, some 17 months after its official discovery observation atSimeiz Observatory.[1]
Thisminor planet was named after the medieval city ofAni, which was destroyed by an earthquake in 1319. The ruins of the former capital of the Armenian kingdom are located near the border to Armenia, in what is now Turkey. Ani was known as "the city of 1001 churches". Thenaming was also mentioned inThe Names of the Minor Planets byPaul Herget in 1955 (H 79).[2]
In theTholen classification,Ani is a common, carbonaceousC-type asteroid.[3] It is also a common C-type in the Tholen-like taxonomy of theSmall Solar System Objects Spectroscopic Survey (S3OS2), while in the survey's SMASS-like taxonomic variant, the asteroid is a hydrated carbonaceous subtype (Ch).[4][12]
In May 2018, a rotationallightcurve ofAni was obtained fromphotometric observations by American amateur astronomerTom Polakis at the Command Module Observatory (V02) in Arizona . Lightcurve analysis gave a well-definedrotation period of11.174±0.004 hours with a brightness variation of0.28±0.02magnitude (U=3).[10]
In June 2002,Brian Warner at hisPalmer Divide Observatory first observed this asteroid and later derived a period of16.8±0.1 hours and an amplitude of0.35±0.05 magnitude, based on poor data (U=1).[a] In December 2004, and in May 2007, two periods of22.850±0.003 h and22.85±0.05 h with a corresponding amplitude of0.17±0.01 and0.38±0.02 magnitude were determined by European astronomers Raymond Poncy (177) as well as Yves Revaz,Raoul Behrend,Alain Klotz, Michel Hernandez, Robert Soubie, Jean-François Gauthier, Bernard Tregon,Pierre Antonini,Laurent Bernasconi, Federico Manzini (A12), Yassine Damerdji and Horacio Correia. The two periods are slightly longer than twice Polakis' period solution (U=2/2−).[14] In April 2007, astronomers at theOakley Observatory (916), Indiana, obtained a period of16.72±0.03 hours and an amplitude of0.32±0.05 magnitude (U=2).[15] In February 2011, French amateur astronomerRené Roy determined a period of12±0.5 hours and a brightness variation of0.38±0.02 magnitude (U=2).[14]
A modeled lightcurve byJosef Ďurech andJosef Hanuš, using photometric data including from theLowell Photometric Database and from theWide-field Infrared Survey Explorer (WISE) was published in 2018. It gave a sidereal period of11.16954±0.00002 and twospin axes at (94.0°, −25.0°) and (269.0°, 4.0°) inecliptic coordinates (λ, β).[16][11]
According to the surveys carried out by the JapaneseAkari satellite, theNEOWISE mission of NASA'sWide-field Infrared Survey Explorer (WISE), and the Infrared Astronomical SatelliteIRAS,Ani measures (97.87±1.15), (99.799±11.027) and (103.52±1.9) kilometers in diameter and its surface has analbedo of (0.037±0.001), (0.035±0.016) and (0.0329±0.001), respectively.[7][8][9] TheCollaborative Asteroid Lightcurve Link adopts the results obtained by IRAS, that is, an albedo of 0.0329 and a diameter of 103.52 kilometers based on anabsolute magnitude of 9.25.[11] Alternative mean-diameter measurements published by the WISE team include (82.500±5.957 km), (83.31±21.31 km), (93.29±31.33 km) and (116.865±1.024 km) with corresponding albedos of (0.0518±0.0131), (0.04±0.02), (0.04±0.02) and (0.026±0.003).[4][11] On 7 April 2000, anasteroid occultation ofAni gave a best-fit ellipse dimension of (65.7 km × 103.5 km) with a good quality rating of 3. These timed observations are taken when the asteroid passes in front of a distant star.[4]
