| Discovery[1] | |
|---|---|
| Discovered by | K. Endate K. Watanabe |
| Discovery site | Kitami Obs. |
| Discovery date | 14 February 1991 |
| Designations | |
| (16525) Shumarinaiko | |
Named after | Lake Shumarinai[2] (Japanese lake) |
| 1991 CU2 · 1996 TE51 | |
| main-belt · (inner)[3] Nysa[4] | |
| Orbital characteristics[1] | |
| Epoch 4 September 2017 (JD 2458000.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 67.29 yr (24,578 days) |
| Aphelion | 2.7341AU |
| Perihelion | 2.0648 AU |
| 2.3995 AU | |
| Eccentricity | 0.1395 |
| 3.72yr (1,358 days) | |
| 30.750° | |
| 0° 15m 54.72s / day | |
| Inclination | 2.4279° |
| 7.6547° | |
| 180.19° | |
| Knownsatellites | 1 (D: 0.83 km;P: 14.409 h)[5][6][a] |
| Physical characteristics | |
| Dimensions | 5.253±0.146 km[7][8] 5.66 km(calculated)[3] |
| 2.5932±0.0003h[6] 2.6425±0.0006 h(poor)[9] 8.8±0.3 h(poor)[10] | |
| 0.20(assumed)[3] 0.306±0.033[7][8] | |
| S(assumed)[3] | |
| 13.3[8] · 13.6[1][3] · 14.37±0.56[11] | |
16525 Shumarinaiko (provisional designation1991 CU2) is a stonyNysian asteroid and synchronousbinary system from the inner regions of theasteroid belt, approximately 5 kilometers in diameter. It was discovered on 14 February 1991, by Japanese astronomersKin Endate andKazuro Watanabe at theKitami Observatory on the island of Hokkaidō in northern Japan.[12] The asteroid was named after the JapaneseLake Shumarinai.[2] Its sub-kilometer sizedminor-planet moon was discovered in 2013.
Shumarinaiko is a member of theNysa family (405),[3][4] the largestasteroid family of the main belt, consisting of stony and carbonaceous subfamilies. The family, named after44 Nysa, is located in the inner belt near theKirkwood gap (3:1 orbital resonance with Jupiter), a depleted zone that separates the central main belt.[13]
It orbits the Sun in theinner asteroid belt at a distance of 2.1–2.7 AU once every 3 years and 9 months (1,358 days). Its orbit has aneccentricity of 0.14 and aninclination of 2° with respect to theecliptic.[1]
The body'sobservation arc begins with aprecovery from theDigitized Sky Survey. It was taken atPalomar Observatory in March 1950, almost 41 years prior to the asteroid's official discovery observation at Kitami in 1991.[12]
Shumarinaiko is an assumed stonyS-type asteroid.[3]
In January 2013, a rotationallightcurve of Shumarinaiko was obtained from photometric observations byBrian Warner at the Palmer Divide Observatory (716) in Colorado, and Dan Coley at DanHenge Observatory (U80) in California. Analysis of the bimodal lightcurve gave a well-definedrotation period of 2.5932 hours with a brightness amplitude of 0.08magnitude (U=3),[6][a] superseding the results from previous observations that gave a period of 2.6425 and 8.8 hours, respectively (U=1/1).[9][10] A low brightness amplitude typically indicates that the body is rather spherical in shape.
During the photometric observation by Warner and Coley in January 2013(see above), mutualoccultation and eclipsing events revealed that Shumarinaiko is a synchronousbinary asteroid with an elongatedminor-planet moon in orbit. The satellite, provisionally designatedS/2013 (16525) 1, seems to be tidally locked to itsorbital period of 14.409 hours. It measures least 16% of its primary (Ds/Dp of <0.16±0.02),[6][a] which translates into a diameter of approximately 830 meters.[5] There are more than100 binary asteroids known to exist in the asteroid belt.
According to the survey carried out by theNEOWISE mission of NASA'sWide-field Infrared Survey Explorer, Shumarinaiko measures 5.253 kilometers in diameter and its surface has analbedo of 0.306,[7][8] while theCollaborative Asteroid Lightcurve Link assumes a standard albedo for stony asteroids of 0.20 and calculates a diameter of 5.66 kilometers based on anabsolute magnitude of 13.6.[3]
Thisminor planet was named afterLake Shumarinai. The lake is located within theShumarinai Prefectural Natural Park in northernHokkaidō, Japan. Artificially created to generatehydroelectricity in the 1940s, it is now known for its scenery.[2] The official naming citation was published by theMinor Planet Center on 15 December 2005 (M.P.C. 55722).[14]
