| Discovery[1] | |
|---|---|
| Discovered by | G. Neujmin |
| Discovery site | Simeiz Obs. |
| Discovery date | 5 September 1915 |
| Designations | |
| (917) Lyka | |
Named after | Lyka, a friend of the discoverer's sister[2] |
| A915 RR · 1950 BS 1951 JJ · 1915 S4 1915 Σ4 | |
| main-belt[1][3] · (inner) background[4][5] | |
| Orbital characteristics[3] | |
| Epoch 31 May 2020 (JD 2459000.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 100.18yr (36,591 d) |
| Aphelion | 2.8590AU |
| Perihelion | 1.9035 AU |
| 2.3812 AU | |
| Eccentricity | 0.2006 |
| 3.67 yr (1,342 d) | |
| 181.91° | |
| 0° 16m 5.52s / day | |
| Inclination | 5.1264° |
| 343.38° | |
| 359.90° | |
| Physical characteristics | |
| 7.867±0.006 h | |
| X(S3OS2)[9] | |
| 11.6[1][3] | |
917 Lyka (prov. designation:A915 RRor1915 S4) is abackground asteroid, approximately 32 kilometers (20 miles) in diameter, located in the inner region of theasteroid belt. It was discovered on 5 September 1915, by Russian astronomerGrigory Neujmin at theSimeiz Observatory on the Crimean peninsula.[1] TheX-type asteroid has arotation period of 7.9 hours and is likely spherical in shape. It was named after Lyka, a friend of the discoverer's sister.[2]
Lyka is a non-family asteroid of the main belt'sbackground population when applying thehierarchical clustering method to itsproper orbital elements.[4][5] It orbits the Sun in theinner main-belt at a distance of 1.9–2.9 AU once every 3 years and 8 months (1,342 days;semi-major axis of 2.38 AU). Its orbit has aneccentricity of 0.20 and aninclination of 5° with respect to theecliptic.[3] The body'sobservation arc begins at Simeiz on 1 September 1926, eleven years after to its official discovery observation.[1]
Thisminor planet was named after Lyka, a friend of the sister of discovererGrigory Neujmin.Lutz Schmadel, the author of theDictionary of Minor Planet Names learned about the meaning of the asteroid's name from private communications with long-time Simeiz astronomerNikolai Chernykh.[2]
In both the Tholen- and SMASS-like taxonomy of theSmall Solar System Objects Spectroscopic Survey (S3OS2),Lyka is anX-type asteroid.[5][9]
In January 2005, a rotationallightcurve ofLyka was obtained fromphotometric observations by Matthieu Conjat. Lightcurve analysis gave a well-definedrotation period of7.867±0.006 hours with a low brightness variation of0.17±0.02magnitude, indicative of a rather spherical shape (U=3).[10] In October 2018, the period was confirmed byLaurent Bernasconi (7.8838±0.0003 h) and by Alfonso Carreño of OBAS (7.889±0.007 h) with amplitudes of0.12±0.01 and0.26±0.03, respectively (U=3/3).[10][11]
According to the survey carried out by the Infrared Astronomical SatelliteIRAS, the JapaneseAkari satellite, and theNEOWISE mission of NASA'sWISE telescope (WISE),Lyka measures (28.10±3.9), (31.29±0.49) and (34.878±0.184) kilometers in diameter and its surface has analbedo of (0.0891±0.031), (0.072±0.003) and (0.056±0.008), respectively.[6][7][8] TheCollaborative Asteroid Lightcurve Link derives an albedo of 0.0520 and a diameter of 27.89 km based on anabsolute magnitude of 11.6.[12] Further published mean-diameters by the WISE team include (21.60±4.99 km), (26.65±9.28 km), (34.789±2.565 km) and (37.843±0.227 km) with albedos between (0.026±0.009) and (0.05±0.02).[5][12] Anasteroid occultation, observed on 4 March 2005, gave a best-fit ellipse dimension of 28.0×28.0 kilometers.[5] These timed observations are taken when the asteroid passes in front of a distant star. However the quality of the measurement is rated poorly.[5]
