Astronomy:4797 Ako
| Discovery [1] | |
|---|---|
| Discovered by | T. Nomura K. Kawanishi |
| Discovery site | Minami-Oda Obs. (374) |
| Discovery date | 30 September 1989 |
| Designations | |
| (4797) Ako | |
| Named after | Akō, Hyōgo (Japanese city)[2] |
| 1989 SJ · 1978 VY9 1985 QB4 | |
| Minor planet category | main-belt · Nysa [3] |
| Orbital characteristics [1] | |
| Epoch 4 September 2017 (JD 2458000.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 38.49 yr (14,057 days) |
| |{{{apsis}}}|helion}} | 2.8553 AU |
| |{{{apsis}}}|helion}} | 1.9714 AU |
| 2.4133 AU | |
| Eccentricity | 0.1831 |
| Orbital period | 3.75 yr (1,369 days) |
| Mean anomaly | 146.42° |
| Mean motion | 0° 15m 46.44s / day |
| Inclination | 1.8108° |
| Longitude of ascending node | 320.82° |
| 78.111° | |
| Physical characteristics | |
| Dimensions | 4.00 km (calculated)[3] 6.000±0.496 km[4][5] |
| Rotation period | 4.085±0.001 h[6] |
| Geometric albedo | 0.112±0.021[4][5] 0.21 (assumed)[3] |
| S [3] | |
| Absolute magnitude (H) | 14.1[4] · 14.3[1][3] · 14.31±0.27[7] |
4797 Ako, provisional designation 1989 SJ, is a stony Nysian asteroid from the inner regions of the asteroid belt, approximately 5 kilometers in diameter. It was discovered on 30 September 1989, by the Japanese astronomers Toshiro Nomura and Kōyō Kawanishi at the Minami-Oda Observatory (374), Japan.[8] The asteroid was named for the Japanese city of Akō.[2]
Orbit and classification
Ako is a member of the stony subgroup of the Nysa family, which is named after its largest member 44 Nysa. It orbits the Sun in the inner main-belt at a distance of 2.0–2.9 AU once every 3 years and 9 months (1,369 days). Its orbit has an eccentricity of 0.18 and an inclination of 2° with respect to the ecliptic.[1]
In 1978, it was first identified as 1978 VY9 at Palomar Observatory, extending the body's observation arc by 11 years prior to its official discovery observation at Minami-Oda Observatory.[8]
Physical characteristics
Rotation period
A rotational lightcurve of Ako was obtained for the first time from photometric observations made at the U.S. Ricky Observatory, Missouri, in November 2008. It gave a well-defined rotation period of 4.085±0.001 hours with a relatively high brightness variation of 0.90 in magnitude ({{{1}}}), indicative of a non-spheroidal shape.[6]
Diameter and albedo
According to NASA's space-based Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission, Ako measures 6.0 kilometers in diameter and its surface has an albedo of 0.11,[4][5] while the Collaborative Asteroid Lightcurve Link (CALL) assumes a standard albedo for stony asteroids of 0.21, and calculates a diameter of 4.0 kilometers, as the higher the albedo (reflectivity), the smaller a body's diameter for a certain absolute magnitude (brightness).[3]
Naming
This minor planet was named for the city of Akō in the Hyōgo Prefecture, Japan, and for its ancient castle on the Seto Inland Sea.[2]
Known for its salt production, Ako is the birthplace of the fictional account of Chūshingura, a tale about the forty-seven Ronin who committed seppuku after avenging their master. The city is also the home of the second discoverer's private Minami-Oda observatory, where Kōyō Kawanishi observes small Solar System bodies.[2] The official naming citation was published by the Minor Planet Center on 27 June 1991 (M.P.C. 18465).[9]
References
- ↑ 1.0 1.1 1.2 1.3 "JPL Small-Body Database Browser: 4797 Ako (1989 SJ)". Jet Propulsion Laboratory. https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2004797.
- ↑ 2.0 2.1 2.2 2.3 Schmadel, Lutz D. (2007). "(4797) Ako". Dictionary of Minor Planet Names – (4797) Ako. Springer Berlin Heidelberg. p. 414. doi:10.1007/978-3-540-29925-7_4700. ISBN 978-3-540-00238-3.
- ↑ 3.0 3.1 3.2 3.3 3.4 3.5 "LCDB Data for (4797) Ako". Asteroid Lightcurve Database (LCDB). http://www.minorplanet.info/PHP/generateOneAsteroidInfo.php?AstInfo=4797%7CAko.
- ↑ 4.0 4.1 4.2 4.3 Mainzer, A.; Grav, T.; Masiero, J.; Hand, E.; Bauer, J.; Tholen, D. et al. (November 2011). "NEOWISE Studies of Spectrophotometrically Classified Asteroids: Preliminary Results". The Astrophysical Journal 741 (2): 25. doi:10.1088/0004-637X/741/2/90. Bibcode: 2011ApJ...741...90M. http://adsabs.harvard.edu/cgi-bin/bib_query?bibcode=2011ApJ...741...90M. Retrieved 4 May 2016.
- ↑ 5.0 5.1 5.2 Masiero, Joseph R.; Mainzer, A. K.; Grav, T.; Bauer, J. M.; Cutri, R. M.; Dailey, J. et al. (November 2011). "Main Belt Asteroids with WISE/NEOWISE. I. Preliminary Albedos and Diameters". The Astrophysical Journal 741 (2): 20. doi:10.1088/0004-637X/741/2/68. Bibcode: 2011ApJ...741...68M. http://adsabs.harvard.edu/cgi-bin/bib_query?bibcode=2011ApJ...741...68M. Retrieved 5 December 2016.
- ↑ 6.0 6.1 Bennefeld, Craig; Bass, Stephen; Blair, Ricco; Cunningham, Kendrick; Hill, Da'quia; McHenry, Michael et al. (October 2009). "Asteroid Lightcurve Analysis at Ricky Observatory". The Minor Planet Bulletin 36 (4): 147–148. ISSN 1052-8091. Bibcode: 2009MPBu...36..147B. http://adsabs.harvard.edu/cgi-bin/bib_query?bibcode=2009MPBu...36..147B. Retrieved 4 May 2016.
- ↑ 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". Icarus 261: 34–47. doi:10.1016/j.icarus.2015.08.007. Bibcode: 2015Icar..261...34V. http://adsabs.harvard.edu/cgi-bin/bib_query?bibcode=2015Icar..261...34V. Retrieved 4 May 2016.
- ↑ 8.0 8.1 "4797 Ako (1989 SJ)". Minor Planet Center. https://www.minorplanetcenter.net/db_search/show_object?object_id=4797.
- ↑ "MPC/MPO/MPS Archive". Minor Planet Center. https://www.minorplanetcenter.net/iau/ECS/MPCArchive/MPCArchive_TBL.html.
External links
- Asteroid Lightcurve Database (LCDB), query form (info )
- Dictionary of Minor Planet Names, Google books
- Asteroids and comets rotation curves, CdR – Observatoire de Genève, Raoul Behrend
- Discovery Circumstances: Numbered Minor Planets (1)-(5000) – Minor Planet Center
- 4797 Ako at AstDyS-2, Asteroids—Dynamic Site
- 4797 Ako at the JPL Small-Body Database
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