1125 China

1125 China (prov. designation: 1957 UN1) is a dark background asteroid from the outer regions of the asteroid belt. It was discovered on 30 October 1957, by astronomer Zhāng Yùzhé (Y. C. Chang，张钰哲) at the Chinese Purple Mountain Observatory（紫金山天文台） in Nanjing, and named in honor of the country China.[3] The assumed C-type asteroid has a short rotation period of 5.4 hours and measures approximately 26 kilometers (16 miles) in diameter. Its name and number were actually taken from another asteroid that was considered a lost asteroid at the time, but was eventually rediscovered and given the new designation 3789 Zhongguo. "Zhongguo" means "China" in Chinese (1928 UF).[2][14]

For 1928 UF and 1986 QK1, the asteroid discovered in 1928, lost, and then rediscovered in 1986, see 3789 Zhongguo.

1125 China
Modelled shape of China from its lightcurve
Discovery [1]
Discovered byY. C. Chang [2]
Discovery sitePurple Mountain Obs.
Discovery date30 October 1957
Designations
(1125) China
Named after
China (country)[2]
1957 UN1 · 1959 EL
1971 KX · 1974 VM
A909 BE
Orbital characteristics [1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc108.75 yr (39,722 days)
Aphelion3.8083 AU
Perihelion2.4452 AU
3.1267 AU
Eccentricity0.2180
5.53 yr (2,019 days)
215.01°
0° 10m 41.88s / day
Inclination3.0407°
97.172°
10.745°
Physical characteristics
Mean diameter
21.86±6.06 km[6]
23.95±6.03 km[7]
26.084±0.199 km[8]
26.513±0.354 km[9]
26.64 km (calculated)[10]
30.49±1.97 km[11]
5.367±0.002 h[12]
5.45±0.02 h[13][lower-alpha 1]
  • (132.0°, −46.0°) (λ1/β1)[5]
  • (305.0°, −49.0°) (λ2/β2)[5]
0.057 (assumed)[10]
0.057±0.004[9]
0.06±0.03[7]
0.063±0.009[11]
0.08±0.06[6]
0.0860±0.0223[8]
C (assumed)[10]
11.20[8][11] · 11.26±0.19[12] · 11.60[1][10][7] · 11.70[6]

    Orbit and classification

    China is a non-family asteroid of the main belt's background population when applying the hierarchical clustering method to its proper orbital elements.[4][5] It orbits the Sun in the outer asteroid belt at a distance of 2.4–3.8 AU once every 5 years and 6 months (2,019 days; semi-major axis of 3.13 AU). Its orbit has an eccentricity of 0.22 and an inclination of 3° with respect to the ecliptic.[1] The asteroid was first observed as A909 BE at Heidelberg Observatory in January 1909, where the body's observation arc begins three week later in February 1909, or more than 48 years prior to its official discovery observation at Nanking, China.[3]

    Naming

    This minor planet was named after People's Republic of China where the asteroid was discovered. The official naming citation was published by the Minor Planet Center on 31 May 1988 (M.P.C. 13179).[2][15]

    Accidentally usurped designation
    Main article: 3789 Zhongguo

    While studying in Chicago in 1928, Zhang Yuzhe discovered an asteroid that was given the provisional designation 1928 UF, and later the number 1125. He named it "China" or "中華" (Zhōnghuá). However, this asteroid was not observed beyond its initial appearance and a precise orbit could not be calculated. In 1957, the Purple Mountain Observatory in China discovered a new asteroid, and with Zhang Yuzhe's agreement the new object 1957 UN1 was reassigned the official designation 1125 China in place of the lost 1928 UF. However, in 1986, the newly discovered object 1986 QK1 was confirmed to be a rediscovery of the original 1928 UF, and this object was named 3789 Zhongguo. Zhongguo is the Chinese word for China.[14]

    Physical characteristics

    China is an assumed carbonaceous C-type asteroid.[10]

    Rotation period and poles

    In February 2009, a rotational lightcurve of China was obtained from photometric observations by Kenneth T. Menzies at the Tigh Speuran Observatory (I14) in Massachusetts, United States. Lightcurve analysis gave a well-defined rotation period of 5.367 hours with a brightness variation of 0.38 magnitude (U=3).[12] In October 2013, Robert Stephens measured a similar period of 5.45 hours and an amplitude of 0.62 magnitude at the Center for Solar System Studies (U81) in California (U=3-).[13][lower-alpha 1]

    Published in 2016, an additional lightcurve was modeled from photometric data obtained by a large international collaboration of astronomers. Modelling gave a concurring sidereal rotation period of 5.36863±0.00005 hours, as well as two spin axes of (132.0°, −46.0°) and (305.0°, −49.0°) in ecliptic coordinates.[16]

    Diameter and albedo

    According to the surveys carried out by the Japanese Akari satellite and the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, China measures between 21.86 and 30.49 kilometers in diameter and its surface has an albedo between 0.057 and 0.0860.[6][7][8][9][11]

    The Collaborative Asteroid Lightcurve Link assumes a standard albedo for carbonaceous asteroids of 0.057 and calculates a diameter of 26.64 kilometers based on an absolute magnitude of 11.6.[10]

    Notes
    1. Stephens (2013): lightcurve plot of (1125) China, rotation period 5.45±0.02 hours. Summary figures at the LCDB

    References
    1. "JPL Small-Body Database Browser: 1125 China (1957 UN1)" (2017-10-29 last obs.). Jet Propulsion Laboratory. Retrieved 23 January 2018.
    2. Schmadel, Lutz D. (2007). Dictionary of Minor Planet Names – (1125) China. Springer Berlin Heidelberg. p. 95. doi:10.1007/978-3-540-29925-7_1126. ISBN 978-3-540-00238-3.
    3. "1125 China (1957 UN1)". Minor Planet Center. Retrieved 23 January 2018.
    4. "Asteroid 1125 China – Proper Elements". AstDyS-2, Asteroids – Dynamic Site. Retrieved 13 March 2020.
    5. "Asteroid 1125 China". Small Bodies Data Ferret. Retrieved 13 March 2020.
    6. Nugent, C. R.; Mainzer, A.; Bauer, J.; Cutri, R. M.; Kramer, E. A.; Grav, T.; et al. (September 2016). "NEOWISE Reactivation Mission Year Two: Asteroid Diameters and Albedos". The Astronomical Journal. 152 (3): 12. arXiv:1606.08923. Bibcode:2016AJ....152...63N. doi:10.3847/0004-6256/152/3/63.
    7. Nugent, C. R.; Mainzer, A.; Masiero, J.; Bauer, J.; Cutri, R. M.; Grav, T.; et al. (December 2015). "NEOWISE Reactivation Mission Year One: Preliminary Asteroid Diameters and Albedos". The Astrophysical Journal. 814 (2): 13. arXiv:1509.02522. Bibcode:2015ApJ...814..117N. doi:10.1088/0004-637X/814/2/117.
    8. 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. arXiv:1109.6407. Bibcode:2011ApJ...741...90M. doi:10.1088/0004-637X/741/2/90.
    9. 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. arXiv:1109.4096. Bibcode:2011ApJ...741...68M. doi:10.1088/0004-637X/741/2/68.
    10. "LCDB Data for (1125) China". Asteroid Lightcurve Database (LCDB). Retrieved 23 January 2018.
    11. Usui, Fumihiko; Kuroda, Daisuke; Müller, Thomas G.; Hasegawa, Sunao; Ishiguro, Masateru; Ootsubo, Takafumi; et al. (October 2011). "Asteroid Catalog Using Akari: AKARI/IRC Mid-Infrared Asteroid Survey". Publications of the Astronomical Society of Japan. 63 (5): 1117–1138. Bibcode:2011PASJ...63.1117U. doi:10.1093/pasj/63.5.1117. Retrieved 17 October 2019. (online, AcuA catalog p. 153)
    12. Menzies, Kenneth T. (July 2009). "Lightcurve Analysis of 1125 China" (PDF). Minor Planet Bulletin. 36 (3): 83–84. Bibcode:2009MPBu...36...83M. ISSN 1052-8091.
    13. Stephens, Robert D. (April 2014). "Asteroids Observed from CS3: 2013 October-December" (PDF). Minor Planet Bulletin. 41 (2): 92–95. Bibcode:2014MPBu...41...92S. ISSN 1052-8091.
    14. Schmadel, Lutz D. (2007). Dictionary of Minor Planet Names – (3789) Zhongguo. Springer Berlin Heidelberg. p. 320. doi:10.1007/978-3-540-29925-7_3783. ISBN 978-3-540-00238-3.
    15. "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 23 January 2018.
    16. Hanuš, J.; Ďurech, J.; Oszkiewicz, D. A.; Behrend, R.; Carry, B.; Delbo, M.; et al. (February 2016). "New and updated convex shape models of asteroids based on optical data from a large collaboration network". Astronomy and Astrophysics. 586: A108. arXiv:1510.07422. Bibcode:2016A&A...586A.108H. doi:10.1051/0004-6361/201527441. ISSN 0004-6361.
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