1111 Reinmuthia

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1111 Reinmuthia
1111Reinmuthia (Lightcurve Inversion).png
Lightcurve-based 3D inversion model of Reinmuthia
Discovery [1]
Discovered by K. Reinmuth
Discovery site Heidelberg Obs.
Discovery date 11 February 1927
MPC designation (1111) Reinmuthia
Named after
Karl Reinmuth[2]
(the discoverer himself)
1927 CO · 1929 QG
main-belt · (outer)[3]
background [4]
Orbital characteristics[1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc 90.72 yr (33,137 days)
Aphelion 3.2947 AU
Perihelion 2.6911 AU
2.9929 AU
Eccentricity 0.1008
5.18 yr (1,891 days)
0° 11m 25.44s / day
Inclination 3.8917°
Physical characteristics
Mean diameter
24.38±0.48 km[5]
41.26 km (derived)[3]
4.00742±0.00005 h[6]
4.007347 h[7]
4.00750±0.00003 h[6]
4.0075±0.0001 h[8][a]
4.02 h[9]
0.057 (assumed)[3]
Tholen = FXU: [1][3]
B–V = 0.639±0.016[1]
U–B = 0.230±0.030[1]
10.65[3][9] · 10.67[1][5]

1111 Reinmuthia, provisional designation 1927 CO, is a very elongated asteroid from the background population in the outer region of the asteroid belt. It was discovered on 11 February 1927, by German astronomer Karl Reinmuth at the Heidelberg Observatory in southwest Germany.[10] It measures approximately 40 kilometers in diameter and has a short rotation period of 4.02 hours for its size.[3] The asteroid was later named in honor of the discoverer.[2]

Orbit and classification[edit]

Reinmuthia is a non-family asteroid from the main belt's background population.[4] It orbits the Sun in the outer asteroid belt at a distance of 2.7–3.3 AU once every 5 years and 2 months (1,891 days; semi-major axis of 2.99 AU). Its orbit has an eccentricity of 0.10 and an inclination of 4° with respect to the ecliptic.[1] The body's observation arc begins at Heidelberg with its official discovery observation.[10]

Physical characteristics[edit]

In the Tholen classification, Reinmuthia has an ambiguous spectral type, closest to that of a dark F-type and somewhat similar to an X-type asteroid. The spectrum had also been flagged as "unusual" and "nosy" by Tholen (FXU:).[1]

Rotation period[edit]

Rotational lightcurves of Reinmuthia have been obtained from photometric observations by American astronomer Richard Binzel as well as by Hiromi and Hiroko Hamanowa at the Hamanowa Astronomical Observatory (D91) in Japan (U=3/3/3).[6][8][9] Lightcurve analysis gave a consolidated, well-defined rotation period of 4.02 hours with a high brightness amplitude between 0.61 and 0.95 magnitude (U=3).[3][a]

Poles and shape[edit]

Lightcurve inversion also modeled the body's shape and poles. In 2013, modelling by an international study using photometric data from the US Naval Observatory, the Uppsala Asteroid Photometric Catalogue, the Palomar Transient Factory and the Catalina Sky Survey gave a similar sidereal period of 4.007347 hours and two spin axes of (356.0°, 68.0°) and (153.0°, 78.0°) in ecliptic coordinates (λ, β). The body's very elongated shape had already been indicated by the high brightness variation measured during the photometric observations.[7]

Diameter and albedo[edit]

According to the survey carried out by the Japanese Akari satellite, Reinmuthia measures 24.38 kilometers in diameter and its surface has an albedo of 0.167.[5] The Collaborative Asteroid Lightcurve Link assumes a standard albedo for carbonaceous asteroids of 0.057 and derives a diameter of 41.26 kilometers based on an absolute magnitude of 10.65.[3]


This minor planet was named after its discoverer, Karl Reinmuth (1892–1979), a German astronomer at the Heidelberg-Königstuhl State Observatory and a prolific discoverer of minor planets. In total, he discovered 395 asteroids, most of them during the 1920s and 1930s, which was a unique record for many years. His discoveries include 1862 Apollo and 69230 Hermes, two lost asteroids and near-Earth objects as well as several large Jupiter trojans. His 1931-discovered asteroid (11435) 1931 UB is the oldest discovered yet still unnamed asteroid. The official naming citation was mentioned in The Names of the Minor Planets by Paul Herget in 1955 (H 104).[2]


  1. ^ a b Lightcurve plot of (1111) Reinmuthia, by H. & H. Hamanowa (2009) from observations at the Hamanowa Astronomical Observatory (D91). Rotation period 4.0075±0.0001 hours (0.166979 days) and a brightness amplitude of 0.945±0.005 mag. Summary figures at the LCDB


  1. ^ a b c d e f g h "JPL Small-Body Database Browser: 1111 Reinmuthia (1927 CO)" (2017-11-02 last obs.). Jet Propulsion Laboratory. Retrieved 26 January 2018. 
  2. ^ a b c Schmadel, Lutz D. (2007). Dictionary of Minor Planet Names – (1111) Reinmuthia. Springer Berlin Heidelberg. p. 94. ISBN 978-3-540-00238-3. Archived from the original on 15 September 2016. Retrieved 26 January 2018. 
  3. ^ a b c d e f g h "LCDB Data for (1111) Reinmuthia". Asteroid Lightcurve Database (LCDB). Retrieved 26 January 2018. 
  4. ^ a b "Small Bodies Data Ferret". Nesvorny HCM Asteroid Families V3.0. Retrieved 26 January 2018. 
  5. ^ a b c d 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 26 January 2018. 
  6. ^ a b c Behrend, Raoul. "Asteroids and comets rotation curves – (1111) Reinmuthia". Geneva Observatory. Retrieved 26 January 2018. 
  7. ^ a b Hanus, J.; Durech, J.; Broz, M.; Marciniak, A.; Warner, B. D.; Pilcher, F.; et al. (March 2013). "Asteroids' physical models from combined dense and sparse photometry and scaling of the YORP effect by the observed obliquity distribution" (PDF). Astronomy and Astrophysics. 551: 16. arXiv:1301.6943Freely accessible. Bibcode:2013A&A...551A..67H. doi:10.1051/0004-6361/201220701. Retrieved 26 January 2018. 
  8. ^ a b Hamanowa, Hiromi; Hamanowa, Hiroko (July 2009). "Lightcurves of 494 Virtus, 556 Phyllis, 624 Hektor 657 Gunlod, 111 Reinmuthia, 1188 Gothlandia, and 1376 Michelle". The Minor Planet Bulletin. 36 (3): 87–88. Bibcode:2009MPBu...36...87H. ISSN 1052-8091. Retrieved 26 January 2018. 
  9. ^ a b c Binzel, R. P. (October 1987). "A photoelectric survey of 130 asteroids". Icarus: 135–208. Bibcode:1987Icar...72..135B. doi:10.1016/0019-1035(87)90125-4. ISSN 0019-1035. Retrieved 26 January 2018. 
  10. ^ a b "1111 Reinmuthia (1927 CO)". Minor Planet Center. Retrieved 26 January 2018. 

External links[edit]