|Discovered by||A. Nakamura|
|Discovery site||Kuma Kogen Obs.|
|Discovery date||4 February 1998|
|MPC designation||(15415) Rika|
|Rika Akana (character in the drama Tokyo Love Story)|
1998 CA1 · 1983 PC1|
1983 PH · 1997 WK22
main-belt  · (inner)|
background  · Flora 
|Orbital characteristics |
|Epoch 23 March 2018 (JD 2458200.5)|
|Uncertainty parameter 0|
|Observation arc||63.41 yr (23,161 d)|
|3.27 yr (1,193 d)|
|0° 18m 6.48s / day|
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. The presumed S-type asteroid has a rotation period of 6.36 hours and possibly an elongated shape. It was named after Rika Akana, a character in the Japanese film and later television adapted drama Tokyo Love Story.
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. 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.
It orbits the Sun in the inner asteroid belt at a distance of 1.7–2.7 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.
The body'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.
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).[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. The Collaborative Asteroid Lightcurve Link assumes an albedo of 0.24 – derived from 8 Flora, the parent body of the Flora family – and calculates a diameter of 3.74 kilometers based on an absolute magnitude of 14.3.
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 Kumakōgen, where the discovering observatory of this asteroid is located.
- 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 ±0.0007 hours (basically identical with 6.3632±0.0008 h) and a brightness amplitude of 6.3636 mag. Quality code is 3. Summary figures at the 1.06LCDB.
- "15415 Rika (1998 CA1)". Minor Planet Center. Retrieved 28 May 2018.
- "JPL Small-Body Database Browser: 15415 Rika (1998 CA1)" (2018-04-24 last obs.). Jet Propulsion Laboratory. Retrieved 28 May 2018.
- "Asteroid 15415 Rika". Small Bodies Data Ferret. Retrieved 28 May 2018.
- "LCDB Data for (15415) Rika". Asteroid Lightcurve Database (LCDB). Retrieved 28 May 2018.
- Masiero, Joseph R.; Nugent, C.; Mainzer, A. K.; Wright, E. L.; Bauer, J. M.; Cutri, R. M.; et al. (October 2017). "NEOWISE Reactivation Mission Year Three: Asteroid Diameters and Albedos" (PDF). The Astronomical Journal. 154 (4): 10. arXiv: . Bibcode:2017AJ....154..168M. doi:10.3847/1538-3881/aa89ec. Retrieved 28 May 2018.
- Husárik, M.; Kusnirák, P. (February 2008). "Relative photometry of numbered asteroids (1314), (2257), (3541), (4080), (4155), (12081) and (15415)". Contributions of the Astronomical Observatory Skalnaté Pleso: 47–60. Bibcode:2008CoSka..38...47H.
- Veres, Peter; Jedicke, Robert; Fitzsimmons, Alan; Denneau, Larry; Granvik, Mikael; Bolin, Bryce; et al. (November 2015). "Absolute magnitudes and slope parameters for 250,000 asteroids observed by Pan-STARRS PS1 - Preliminary results" (PDF). Icarus. 261: 34–47. arXiv: . Bibcode:2015Icar..261...34V. doi:10.1016/j.icarus.2015.08.007. Retrieved 28 May 2018.
- "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 28 May 2018.
- Asteroid Lightcurve Database (LCDB), query form (info)
- Dictionary of Minor Planet Names, Google books
- Discovery Circumstances: Numbered Minor Planets (15001)-(20000) – Minor Planet Center
- 15415 Rika at AstDyS-2, Asteroids—Dynamic Site
- 15415 Rika at the JPL Small-Body Database