1231 Auricula

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1231 Auricula
Discovery [1]
Discovered byK. Reinmuth
Discovery siteHeidelberg Obs.
Discovery date10 October 1931
MPC designation(1231) Auricula
Named after
Primula auricula[2]
(flowering plant)
1931 TE2
main-belt[1][3] · (middle)
Orbital characteristics[3]
Epoch 27 April 2019 (JD 2458600.5)
Uncertainty parameter 0
Observation arc87.02 yr (31,785 d)
Aphelion2.8988 AU
Perihelion2.4388 AU
2.6688 AU
4.36 yr (1,593 d)
0° 13m 33.96s / day
Physical characteristics
Mean diameter
13.43±4.67 km[6]
15.10±3.67 km[7]
18.71±0.65 km[8][9]
21.44±0.81 km[10]
22.52±1.8 km[11]
3.9816±0.0006 h[12]
C (SDSS-MOC)[13]

1231 Auricula, provisional designation 1931 TE2, is a carbonaceous background asteroid from the central regions of the asteroid belt, approximately 20 kilometers (12 miles) in diameter. It was discovered on 10 October 1931, by German astronomer Karl Reinmuth at the Heidelberg Observatory.[1] The likely elongated C-type asteroid has a rotation period of 3.98 hours.[14] It was named after the flowering plant auricula and indirectly honors astronomer Gustav Stracke.[2]

Orbit and classification[edit]

Based on recent HCM-analyses, Auricula is a non-family asteroid that belongs to the main belt's background population.[4][5] On its osculating Keplerian orbital elements, it is located in the Eunomia region (502), where the prominent family of stony stony asteroids is located.[14]

It orbits the Sun in the central main-belt at a distance of 2.4–2.9 AU once every 4 years and 4 months (1,593 days; semi-major axis of 2.67 AU). Its orbit has an eccentricity of 0.09 and an inclination of 11° with respect to the ecliptic.[3] The body's observation arc begins with its official discovery observation at Heidelberg in October 1931.[1]


This minor planet was named after the yellow flowered Alpine primrose, primula auricula. The official naming citation was mentioned in The Names of the Minor Planets by Paul Herget in 1955 (H 113).[2] It honors German astronomer and diligent orbit computer Gustav Stracke (1887–1943), who had asked that no asteroid be named after him. The initials of the asteroids (1227) through (1234), all discovered by Karl Reinmuth, spell out "G. Stracke". In this manner, Reinmuth was able to circumvent Stracke's desire and honor him nevertheless. The asteroid 1019 Strackea was later later named after Stracke directly.[15] In the 1990s, astronomer Brian Marsden was also honored by this method, see asteroids 5694 to 5699. The consecutive initial letters of these minor-planet names spell out "MarsdenB".[16]

Reinmuth's flowers[edit]

Due to his many discoveries, Karl Reinmuth submitted a large list of 66 newly named asteroids in the early 1930s. The list covered his discoveries with numbers between (1009) and (1200). This list also contained a sequence of 28 asteroids, starting with 1054 Forsytia, that were all named after plants, in particular flowering plants (also see list of minor planets named after animals and plants).[17]

Physical characteristics[edit]

In the SDSS-based taxonomy, Auricula is a common, carbonaceous C-type asteroid.[4][13]

Rotation period and poles[edit]

In April 2008, a rotational lightcurve of Auricula was obtained from photometric observations by Colin Bembrick at the Mount Tarana Observatory (431) and other observers from Australia and New Zealand. Lightcurve analysis gave a rotation period of 3.9816±0.0006 hours with a brightness amplitude of 0.75 magnitude (U=3), indicative of a non-spherical, elongated shape.[12] A modeled lightcurve using photometric data from the Lowell Photometric Database was published in 2016. It gave a concurring sidereal period of 3.981580±0.000001 hours, as well as two spin axes at (57.0°, −57.0°) and (225.0°, −85.0°) in ecliptic coordinates (λ, β).[18]

Diameter and albedo[edit]

According to the surveys carried out by the Infrared Astronomical Satellite IRAS, the Japanese Akari satellite and the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Auricula measures between 13.43 and 22.52 kilometers in diameter and its surface has an albedo between 0.066 and 0.11.[6][7][9][8][10][11] The Collaborative Asteroid Lightcurve Link derives an albedo of 0.0465 and a diameter of 22.37 kilometers based on an absolute magnitude of 12.2.[14]


  1. ^ a b c d e "1231 Auricula (1931 TE2)". Minor Planet Center. Retrieved 17 December 2018.
  2. ^ a b c Schmadel, Lutz D. (2007). "(1231) Auricula". Dictionary of Minor Planet Names – (1231) Auricula. Springer Berlin Heidelberg. p. 102. doi:10.1007/978-3-540-29925-7_1232. ISBN 978-3-540-00238-3.
  3. ^ a b c d "JPL Small-Body Database Browser: 1231 Auricula (1931 TE2)" (2018-10-18 last obs.). Jet Propulsion Laboratory. Retrieved 17 December 2018.
  4. ^ a b c "Asteroid 1231 Auricula". Small Bodies Data Ferret. Retrieved 17 December 2018.
  5. ^ a b "Asteroid (1231) Auricula – Proper elements". AstDyS-2, Asteroids – Dynamic Site. Retrieved 14 December 2018.
  6. ^ a b c d 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. ^ a b c d 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. ^ a b c d Mainzer, A. K.; Bauer, J. M.; Cutri, R. M.; Grav, T.; Kramer, E. A.; Masiero, J. R.; et al. (June 2016). "NEOWISE Diameters and Albedos V1.0". NASA Planetary Data System: EAR-A-COMPIL-5-NEOWISEDIAM-V1.0. Bibcode:2016PDSS..247.....M. Retrieved 17 December 2018.
  9. ^ a b c d Masiero, Joseph R.; Mainzer, A. K.; Grav, T.; Bauer, J. M.; Cutri, R. M.; Nugent, C.; et al. (November 2012). "Preliminary Analysis of WISE/NEOWISE 3-Band Cryogenic and Post-cryogenic Observations of Main Belt Asteroids". The Astrophysical Journal Letters. 759 (1): 5. arXiv:1209.5794. Bibcode:2012ApJ...759L...8M. doi:10.1088/2041-8205/759/1/L8.
  10. ^ 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 17 December 2018. (online, AcuA catalog p. 153)
  11. ^ a b c Tedesco, E. F.; Noah, P. V.; Noah, M.; Price, S. D. (October 2004). "IRAS Minor Planet Survey V6.0". NASA Planetary Data System – IRAS-A-FPA-3-RDR-IMPS-V6.0: IRAS-A-FPA-3-RDR-IMPS-V6.0. Bibcode:2004PDSS...12.....T. Retrieved 17 December 2018.
  12. ^ a b Bembrick, Colin; Crawford, Greg; Allen, Bill (October 2008). "The Rotation Period of 1231 Auricula". The Minor Planet Bulletin. 35 (4): 185–186. Bibcode:2008MPBu...35..185B. ISSN 1052-8091. Retrieved 17 December 2018.
  13. ^ a b 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 17 December 2018.
  14. ^ a b c "LCDB Data for (1231) Auricula". Asteroid Lightcurve Database (LCDB). Retrieved 17 December 2018.
  15. ^ Schmadel, Lutz D. (2007). "(1234) Elyna". Dictionary of Minor Planet Names – (1234) Elyna. Springer Berlin Heidelberg. p. 102–103. doi:10.1007/978-3-540-29925-7_1235. ISBN 978-3-540-00238-3.
  16. ^ Schmadel, Lutz D. (2007). "(5699) Munch". Dictionary of Minor Planet Names – (5699) Munch. Springer Berlin Heidelberg. p. 483. doi:10.1007/978-3-540-29925-7_5391. ISBN 978-3-540-00238-3.
  17. ^ Schmadel, Lutz D. (2007). "(1054) Forsytia". Dictionary of Minor Planet Names – (1054) Forsytia. Springer Berlin Heidelberg. p. 90. doi:10.1007/978-3-540-29925-7_1055. ISBN 978-3-540-00238-3.
  18. ^ Durech, J.; Hanus, J.; Oszkiewicz, D.; Vanco, R. (March 2016). "Asteroid models from the Lowell photometric database". Astronomy and Astrophysics. 587: 6. arXiv:1601.02909. Bibcode:2016A&A...587A..48D. doi:10.1051/0004-6361/201527573. Retrieved 17 December 2018.

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