31179 Gongju

31179 Gongju, provisional designation 1997 YR2, is a stony Nysian asteroid from the inner regions of the asteroid belt, approximately 5 kilometers (3 miles) in diameter. It was discovered on 21 December 1997, by Japanese amateur astronomer Naoto Sato at his Chichibu Observatory near Tokyo, central Japan.[1] The S-type asteroid has a rotation period of 4.8 hours and possibly an elongated shape.[3] It was named for the South Korean city of Gongju.[1]

31179 Gongju
Discovery [1]
Discovered byN. Sato
Discovery siteChichibu Obs.
Discovery date21 December 1997
Designations
(31179) Gongju
Named after
Gongju [1]
(South Korean city)
1997 YR2 · 1989 TM9
1999 CS56
main-belt [1][2] · (inner)
Nysa [3][4]
Orbital characteristics [2]
Epoch 23 March 2018 (JD 2458200.5)
Uncertainty parameter 0
Observation arc28.39 yr (10,369 d)
Aphelion2.9123 AU
Perihelion1.9732 AU
2.4427 AU
Eccentricity0.1922
3.82 yr (1,394 d)
192.32°
0° 15m 29.52s / day
Inclination3.4527°
81.303°
248.25°
Physical characteristics
Mean diameter
4.675±0.152 km[5][6]
5.04 km (calculated)[3]
4.829±0.001 h[7]
0.21 (assumed)[3]
0.353±0.028[5][6]
S (SDSS-MOC)[3][8]
13.4[6]
13.8[2][3]

    Orbit and classification

    Gongju is a member of the Nysa family (405),[3][4] the largest asteroid family of the main belt, consisting of stony and carbonaceous subfamilies. The family, named after 44 Nysa, is located near the 3:1 orbital resonance with Jupiter, a depleted zone that separates the inner from the intermediate asteroid belt.[9]

    It orbits the Sun in the inner asteroid belt at a distance of 2.0–2.9 AU once every 3 years and 10 months (1,394 days; semi-major axis of 2.44 AU). Its orbit has an eccentricity of 0.19 and an inclination of 3° with respect to the ecliptic.[2] The body's observation arc begins with its observations as 1989 TM9 at ESO's La Silla Observatory in October 1989, more than 8 years prior to its official discovery observation at Chichibu.[1]

    Physical characteristics

    Based on the Moving Object Catalog (MOC) of the Sloan Digital Sky Survey, Gongju has a spectral type of a stony S-type asteroid.[8]

    Rotation period

    In October 2012, a rotational lightcurve of Gongju was obtained from photometric observations by American astronomer John Ruthroff at the Shadowbox Observatory in Indiana. Lightcurve analysis gave a well-defined rotation period of 4.829 hours with a high brightness amplitude of 0.80 magnitude, indicative of a non-spherical shape (U=3).[7]

    Diameter and albedo

    According to the survey carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Gongju measures 4.675 kilometers in diameter and its surface has an albedo of 0.353,[5][6] while the Collaborative Asteroid Lightcurve Link assumes an albedo of 0.21 and calculates a diameter of 5.04 kilometers based on an absolute magnitude of 13.8.[3]

    Naming

    This minor planet was named after the South Korean city of Gongju, located in Chungcheongnam-do Province. It has a population of approximately 120,000 and was the capital of Baekje dynasty in the 5th century AD and the seat of the provincial government until 1932.[1] The official naming citation was published by the Minor Planet Center on 14 May 2014 (M.P.C. 88406).[10]

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    gollark: Oh no;
    gollark: You can just download them and run them locally if it bothers you much.
    gollark: Why do you ask?
    gollark: You mean 5400 surely?

    References
    1. "31179 Gongju (1997 YR2)". Minor Planet Center. Retrieved 4 May 2018.
    2. "JPL Small-Body Database Browser: 31179 Gongju (1997 YR2)" (2018-02-26 last obs.). Jet Propulsion Laboratory. Retrieved 4 May 2018.
    3. "LCDB Data for (31179) Gongju". Asteroid Lightcurve Database (LCDB). Retrieved 4 May 2018.
    4. "Asteroid 31179 Gongju – Nesvorny HCM Asteroid Families V3.0". Small Bodies Data Ferret. Retrieved 27 October 2019.
    5. 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.
    6. 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. (catalog)
    7. Ruthroff, John C. (April 2013). "Lightcurve Analysis of Main Belt Asteroids 1115 Sabauda 1554 Yugoslavia, 1616 Filipoff, 2890 Vilyujsk, (5153) 1940 GO, and (31179) 1997 YR2". The Minor Planet Bulletin. 40 (2): 90–91. Bibcode:2013MPBu...40...90R. ISSN 1052-8091.
    8. Carvano, J. M.; Hasselmann, P. H.; Lazzaro, D.; Mothé-Diniz, T. (February 2010). "SDSS-based taxonomic classification and orbital distribution of main belt asteroids". Astronomy and Astrophysics. 510: 12. Bibcode:2010A&A...510A..43C. doi:10.1051/0004-6361/200913322. Retrieved 30 October 2019. (PDS data set)
    9. Nesvorný, D.; Broz, M.; Carruba, V. (December 2014). Identification and Dynamical Properties of Asteroid Families. Asteroids IV. pp. 297–321. arXiv:1502.01628. Bibcode:2015aste.book..297N. doi:10.2458/azu_uapress_9780816532131-ch016. ISBN 9780816532131.
    10. "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 4 May 2018.

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