15415 Rika
Main-belt asteroid
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15415 Rika (provisional designation 1998 CA1) is a bright background asteroid from the Florian region of the inner asteroid belt, approximately 3 kilometers (2 miles) in diameter. It was discovered on 4 February 1998, by Japanese astronomer Akimasa Nakamura at the Kuma Kogen Astronomical Observatory in southern Japan.[1] The presumed S-type asteroid has a rotation period of 6.36 hours and possibly an elongated shape.[4] It was named after Rika Akana, a character in the Japanese film and later television adapted drama Tokyo Love Story.[1]
| Discovery[1] | |
|---|---|
| Discovered by | A. Nakamura |
| Discovery site | Kuma Kogen Obs. |
| Discovery date | 4 February 1998 |
| Designations | |
| (15415) Rika | |
Named after | Rika Akana (character in the drama Tokyo Love Story)[1] |
| 1998 CA1 · 1983 PC1 1983 PH · 1997 WK22 | |
| main-belt[1][2] · (inner) background[3] · Flora[4] | |
| Orbital characteristics[2] | |
| Epoch 23 March 2018 (JD 2458200.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 63.41 yr (23,161 d) |
| Aphelion | 2.7047 AU |
| Perihelion | 1.6979 AU |
| 2.2013 AU | |
| Eccentricity | 0.2287 |
| 3.27 yr (1,193 d) | |
| 194.33° | |
| 0° 18m 6.48s / day | |
| Inclination | 7.4787° |
| 327.38° | |
| 28.661° | |
| Physical characteristics | |
| 2.830±0.488 km[5] 3.74 km (calculated)[4] | |
| 6.3636±0.0008 h[6][a] | |
| 0.24 (assumed)[4] 0.6053±0.2264[5] | |
| S (assumed)[4] | |
| 14.2[2][1] 14.21[5][7] 14.3[4] | |
Orbit and classification
Rika is a non-family asteroid of the main belt's background population when applying the hierarchical clustering method to its proper orbital elements.[3] Based on osculating Keplerian orbital elements, the asteroid has also been classified as a member of the Flora family (402), a giant asteroid family and the largest family of stony asteroids in the main-belt.[4]
It orbits the Sun in the inner asteroid belt at a distance of 1.7â2.7 astronomical units (AU) once every 3 years and 3 months (1,193 days; semi-major axis of 2.2 AU). Its orbit has an eccentricity of 0.23 and an inclination of 7° with respect to the ecliptic.[2]
Rika's observation arc begins with a precovery published by the Digitized Sky Survey and taken at the Palomar Observatory in November 1954, more than 43 years prior to its official discovery observation at Kuma Kogen.[1]
Physical characteristics
Rika is an assumed, common S-type asteroid,[4] despite the exceptionally high albedo (see below) measured by the Wide-field Infrared Survey Explorer (WISE).
Rotation period
In October 2006, a rotational lightcurve of Rika was obtained from photometric observations by astronomers at the Skalnaté pleso Observatory in Slovakia. Lightcurve analysis gave a well-defined rotation period of 6.3636 hours with a high brightness amplitude of 1.06 magnitude, indicating that the body has an elongated shape (U=3).[6][a]
Diameter and albedo
According to the survey carried out by the NEOWISE mission of NASA's WISE telescope, Rika measures 2.830 kilometers in diameter and its surface has a high albedo of 0.6053.[5] The Collaborative Asteroid Lightcurve Link assumes an albedo of 0.24 â derived from 8 Flora, the parent body of the Flora family â and calculates a diameter of 3.74 kilometers based on an absolute magnitude of 14.3.[4]
Naming
This minor planet was named after Rika Akana, the heroine played by Honami Suzuki in the manga-based Japanese television drama Tokyo Love Story. Some episodes of the dorama were filmed on locations near the town of KumakÅgen, where the discovering observatory of this asteroid is located.[1]
The official naming citation was published by the Minor Planet Center on 13 October 2000 (M.P.C. 41388).[8]
Notes
- Pravec (2006) Lightcurve plot of (15415) Rika by Husárik and Kusnirák, from Ondrejov data published by the NEO Photometric Program and collaborating projects: rotation period 6.3632±0.0007 hours (basically identical with 6.3636±0.0008 h) and a brightness amplitude of 1.06 mag. Quality code is 3. Summary figures at the LCDB.
