1180 Rita

1180 Rita, provisional designation 1931 GE, is a dark and spheroidal Hildian asteroid from the outermost regions of the asteroid belt, approximately 97 kilometers in diameter. It was discovered on 9 April 1931, by German astronomer Karl Reinmuth at the Heidelberg Observatory in southwest Germany.[3] Any reference of its later name, Rita, is unknown.[2]

1180 Rita
Discovery[1]
Discovered byK. Reinmuth
Discovery siteHeidelberg Obs.
Discovery date9 April 1931
Designations
(1180) Rita
Named after
unknown[2]
1931 GE · 1929 CM
1953 AH · 1957 UF1
A907 GG · A908 KA
A916 LA
main-belt · (outer)[1] · Hilda[3][4]
Orbital characteristics[1]
Epoch 16 February 2017 (JD 2457800.5)
Uncertainty parameter 0
Observation arc109.98 yr (40,172 days)
Aphelion4.6127 AU
Perihelion3.3574 AU
3.9851 AU
Eccentricity0.1575
7.96 yr (2,906 days)
209.15°
0° 7m 26.04s / day
Inclination7.1985°
88.336°
209.12°
Jupiter MOID0.6111 AU
Physical characteristics
Mean diameter
82.72 km (calculated)[4]
97 km[1]
97.63±2.30 km[5]
9 h[6]
9.605±0.006 h[7]
12 h[8]
13.090±0.002 h[lower-alpha 1]
14.72 h[9]
14.902 h[10]
20.496±0.005 h[lower-alpha 2]
0.041±0.002[5]
0.044±0.008[11]
0.048[1]
0.057 (assumed)[4]
0.058±0.009[12]
Tholen = P[1] · P[4][11]
B–V = 0.682[1] · 0.670±0.010[lower-alpha 2]
U–B = 0.216[1]
V–R = 0.440±0.010[lower-alpha 2]
9.14[1][4][5] · 9.17±0.19[13]

    Orbit and classification

    Rita belongs to the orbital Hilda group which is located in the outermost part of the main-belt.[4] Asteroids in this dynamical group have semi-major axis between 3.7 and 4.2 AU and stay in a 3:2 resonance with the gas giant Jupiter. Rita, however, is a background asteroid and not a member of the (collisional) Hilda family (101).[14] Hildian asteroids are thought to have originated from the Kuiper belt.

    The asteroid orbits the Sun at a distance of 3.4–4.6 AU once every 7 years and 12 months (2,906 days). Its orbit has an eccentricity of 0.16 and an inclination of 7° with respect to the ecliptic.[1]

    It was first observed as A907 GG at Heidelberg in 1907. The body's observation arc begins at Heidelberg in 1908, when it was identified as A908 KA, approximately 23 years prior to its official discovery observation.[3]

    Physical characteristics

    In the Tholen taxonomy, Rita is a dark and reddish P-type asteroid.[1] The P-type asteroids are some of the darkest objects in the Solar System.

    Rotation period

    Since 1983, several rotational lightcurves of Rita have been obtained from photometric observations. Lightcurve analysis gave a wide range of divergent rotation periods between 9 and 20.5 hours.[6][7][8][9][10][lower-alpha 2] The Light Curve Data Base adopts a period of 13.090 hours with a brightness amplitude of 0.06 magnitude. Bodies with such a low brightness variation are typically of a spherical rather than elongated shape. The lightcurve was obtained in January 2017, by American astronomer Brian Warner at the Center for Solar System Studies in California (U=2).[lower-alpha 1]

    Diameter and albedo

    According to the surveys carried out by the Japanese Akari satellite, and NASA's Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission, Rita measures 97 kilometers in diameter and its surface has an albedo between 0.041 and 0.058.[5][11][12] The Collaborative Asteroid Lightcurve Link assumes a standard albedo for carbonaceous, outer main-belt asteroids of 0.057, and calculates a diameter of 82.72 kilometers with on an absolute magnitude of 9.14.[4]

    Naming

    Any reference of this minor planet's name to a person or occurrence is unknown.[2]

    Unknown meaning

    Among the many thousands of named minor planets, Rita is one of 120 asteroids, for which no official naming citation has been published. All of these low-numbered asteroids have numbers between 164 Eva and 1514 Ricouxa and were discovered between 1876 and the 1930s, predominantly by astronomers Auguste Charlois, Johann Palisa, Max Wolf and Karl Reinmuth.[15]

    Notes
    1. Warner (2017) web: lightcurve plot of 1180 Rita – rotation period 13.090±0.002 hours with a brightness amplitude of 0.06±0.01 magnitude. No quality code of 2. Observed between 12 December 2016 and 26 January 2017, with a total of 304 data points. Summary figures at the Light Curve Data Base.
    2. Slyusarev (2012) web: rotation period 20.496±0.005 hours with a brightness amplitude of 0.05 magnitude. No quality code determined. Color Indices for BV and VR are 0.670±0.010 and 0.440±0.010, respectively. Summary figures at the Light Curve Data Base.

    References
    1. "JPL Small-Body Database Browser: 1180 Rita (1931 GE)" (2017-03-29 last obs.). Jet Propulsion Laboratory. Retrieved 27 April 2017.
    2. Schmadel, Lutz D. (2007). "(1180) Rita". Dictionary of Minor Planet Names. Springer Berlin Heidelberg. p. 99. doi:10.1007/978-3-540-29925-7_1181. ISBN 978-3-540-00238-3.
    3. "1180 Rita (1931 GE)". Minor Planet Center. Retrieved 27 April 2017.
    4. "LCDB Data for (1180) Rita". Asteroid Lightcurve Database (LCDB). Retrieved 27 April 2017.
    5. 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. (online, AcuA catalog p. 153)
    6. Binzel, Richard P.; Sauter, Linda M. (February 1992). "Trojan, Hilda, and Cybele asteroids - New lightcurve observations and analysis". Icarus. 95 (2): 222–238. Bibcode:1992Icar...95..222B. doi:10.1016/0019-1035(92)90039-A. ISSN 0019-1035. Retrieved 27 April 2017.
    7. Polishook, David (October 2012). "Lightcurves for Shape Modeling: 852 Wladilena, 1089 Tama, and 1180 Rita". The Minor Planet Bulletin. 39 (4): 242–244. Bibcode:2012MPBu...39..242P. ISSN 1052-8091. Retrieved 27 April 2017.
    8. Behrend, Raoul. "Asteroids and comets rotation curves – (1180) Rita". Geneva Observatory. Retrieved 27 April 2017.
    9. Gonano, M.; Mottola, S.; Neukum, G.; di Martino, M. (December 1990). "Physical study of outer belt asteroids". Space Dust and Debris; Proceedings of the Topical Meeting of the Interdisciplinary Scientific Commission B /Meetings B2. 11 (12): 197–200. Bibcode:1991AdSpR..11..197G. doi:10.1016/0273-1177(91)90563-Y. ISSN 0273-1177. Retrieved 27 April 2017.
    10. Dahlgren, M.; Lahulla, J. F.; Lagerkvist, C.-I.; Lagerros, J.; Mottola, S.; Erikson, A.; et al. (June 1998). "A Study of Hilda Asteroids. V. Lightcurves of 47 Hilda Asteroids". Icarus. 133 (2): 247–285. Bibcode:1998Icar..133..247D. doi:10.1006/icar.1998.5919. Retrieved 27 April 2017.
    11. 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. S2CID 35447010.
    12. Grav, T.; Mainzer, A. K.; Bauer, J.; Masiero, J.; Spahr, T.; McMillan, R. S.; et al. (January 2012). "WISE/NEOWISE Observations of the Hilda Population: Preliminary Results". The Astrophysical Journal. 744 (2): 15. arXiv:1110.0283. Bibcode:2012ApJ...744..197G. doi:10.1088/0004-637X/744/2/197. S2CID 44000310. Retrieved 27 April 2017.
    13. 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. arXiv:1506.00762. Bibcode:2015Icar..261...34V. doi:10.1016/j.icarus.2015.08.007. S2CID 53493339. Retrieved 27 April 2017.
    14. "Asteroid 1180 Rita – Proper Elements". AstDyS-2, Asteroids – Dynamic Site. Retrieved 28 October 2019.
    15. Schmadel, Lutz D. (2007). "Appendix 11 – Minor Planet Names with Unknown Meaning". Dictionary of Minor Planet Names – Fifth Revised and Enlarged revision. Springer Berlin Heidelberg. pp. 927–929. ISBN 978-3-540-00238-3.
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