Astronomy:909 Ulla

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Short description: Outer main-belt asteroid
909 Ulla
909 Ulla orbit on 01 Jan 2009.png
Orbital diagram of Ulla
Discovery [1]
Discovered byK. Reinmuth
Discovery siteHeidelberg Obs.
Discovery date7 February 1919
Designations
(909) Ulla
PronunciationGerman: [ˈʊlaː][4]
Classically: /ˈʌlə/[5]
Named afterUlla Ahrens [2]
(observatory donor)
1919 FA · 1936 SJ
1949 OF1 · 1949 PW
1966 BU · 1966 DM
A912 CA · A919 CA
Minor planet categorymain-belt · (outer) [3]
Ulla · Cybele
Orbital characteristics [6]
Epoch 31 May 2020 (JD 2459000.5)
Uncertainty parameter 0
Observation arc100.99 yr (36,886 d)
|{{{apsis}}}|helion}}3.8633 AU
|{{{apsis}}}|helion}}3.2217 AU
3.5425 AU
Eccentricity0.0906
Orbital period6.67 yr (2,435 d)
Mean anomaly180.34°
Mean motion0° 8m 52.08s / day
Inclination18.797°
Longitude of ascending node146.35°
232.64°
TJupiter3.0250
Physical characteristics
Mean diameter
Rotation period8.73 h[9]
Geometric albedo
  • 0.0343±0.001[8]
  • 0.037±0.001[7]
Absolute magnitude (H)8.95[1][6][7][8]


909 Ulla is a large and dark asteroid from the outermost regions of the asteroid belt, that measures approximately 116 kilometers (72 miles) in diameter. It is the parent body and namesake of the Ulla family, which belongs to the larger group of Cybele asteroids. It was discovered on 7 February 1919, by German astronomer Karl Reinmuth at the Heidelberg Observatory in southwest Germany.[1] The X-type asteroid has a rotation period of 8.7 hours and a notably low value for its Jupiter Tisserand's parameter. It was named after Ulla Ahrens, daughter of a friend of the discoverer.[2]

Orbit and classification

Ulla is the parent body of the Ulla family (903),[11] a very small asteroid family of less than 30 known bodies.[12] It orbits the Sun in the outermost asteroid belt at a distance of 3.2–3.9 AU once every 6 years and 8 months (2,435 days; semi-major axis of 3.54 AU). Its orbit has an eccentricity of 0.09 and an inclination of 19° with respect to the ecliptic.[6]

Naming

This minor planet was named after Ulla Ahrens, a daughter of a friend of the discoverer.[2] Karl Reinmuth also named the asteroid 950 Ahrensa for the Ahrens family, who was a donor of the Heidelberg Observatory. The official naming citation was mentioned in The Names of the Minor Planets by Paul Herget in 1955 (H 50).[2]

Physical characteristics

In the SMASS classification, Ulla is an X-type asteroid.[6][10]

Rotation period

A rotational lightcurve of Ulla was obtained from photometric observations in 2000. Lightcurve analysis gave a rotation period of 8.73 hours with a brightness amplitude between 0.13 and 0.24 magnitude ({{{1}}}).[9] Other photometric period determinations gave concurring results.[13][14]

Diameter and albedo

According to the surveys carried out by the Infrared Astronomical Satellite IRAS and the Japanese Akari satellite, Ulla measures 113.13±1.48 and 116.44±2.4 kilometers in diameter and its surface has an albedo between 0.0343±0.001 and 0.037±0.001.[7][8] The Collaborative Asteroid Lightcurve Link uses an albedo of 0.0450 and derives a diameter of 116.66 kilometers based on an absolute magnitude of 8.65.[3]

References

  1. ↑ 1.0 1.1 1.2 "909 Ulla (1919 FA)". Minor Planet Center. https://www.minorplanetcenter.net/db_search/show_object?object_id=909. 
  2. ↑ 2.0 2.1 2.2 2.3 Schmadel, Lutz D. (2007). "(909) Ulla". Dictionary of Minor Planet Names. Springer Berlin Heidelberg. p. 81. doi:10.1007/978-3-540-29925-7_910. ISBN 978-3-540-00238-3. 
  3. ↑ 3.0 3.1 3.2 "LCDB Data for (909) Ulla". Asteroid Lightcurve Database (LCDB). http://www.minorplanet.info/PHP/generateOneAsteroidInfo.php?AstInfo=909. 
  4. ↑ (German Names)
  5. ↑ Noah Webster (1884) A Practical Dictionary of the English Language
  6. ↑ 6.0 6.1 6.2 6.3 6.4 6.5 6.6 "JPL Small-Body Database Browser: 909 Ulla (A919 CA)". Jet Propulsion Laboratory. https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2000909. 
  7. ↑ 7.0 7.1 7.2 7.3 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. doi:10.1093/pasj/63.5.1117. Bibcode: 2011PASJ...63.1117U.  (online, AcuA catalog p. 153)
  8. ↑ 8.0 8.1 8.2 8.3 Tedesco, E. F.; Noah, P. V.; Noah, M.; Price, S. D. (October 2004). "IRAS Minor Planet Survey V6.0". NASA Planetary Data System 12: IRAS-A-FPA-3-RDR-IMPS-V6.0. Bibcode: 2004PDSS...12.....T. https://sbnarchive.psi.edu/pds3/iras/IRAS_A_FPA_3_RDR_IMPS_V6_0/data/diamalb.tab. Retrieved 23 February 2020. 
  9. ↑ 9.0 9.1 Lagerkvist, Claes-Ingvar; Erikson, Anders; Lahulla, Felix; De Martino, Mario; Nathues, Andreas; Dahlgren, Mats (January 2001). "A Study of Cybele Asteroids. I. Spin Properties of Ten Asteroids". Icarus 149 (1): 190–197. doi:10.1006/icar.2000.6507. Bibcode: 2001Icar..149..190L. 
  10. ↑ 10.0 10.1 De Prá, M. N.; Pinilla-Alonso, N.; Carvano, J. M.; Licandro, J.; Campins, H.; Mothé-Diniz, T. et al. (September 2018). "PRIMASS visits Hilda and Cybele groups". Icarus 311: 35–51. doi:10.1016/j.icarus.2017.11.012. Bibcode: 2018Icar..311...35D. 
  11. ↑ "Asteroid 909 Ulla". Small Bodies Data Ferret. https://sbntools.psi.edu/ferret/SimpleSearch/results.action?targetName=909+Ulla. 
  12. ↑ Nesvorný, D.; Broz, M.; Carruba, V. (December 2014). "Identification and Dynamical Properties of Asteroid Families". Asteroids IV. pp. 297–321. doi:10.2458/azu_uapress_9780816532131-ch016. ISBN 9780816532131. Bibcode: 2015aste.book..297N. 
  13. ↑ Gonano, M.; di Martino, M.; Mottola, S.; Neukum, G. (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. doi:10.1016/0273-1177(91)90563-Y. ISSN 0273-1177. Bibcode: 1991AdSpR..11l.197G. 
  14. ↑ Behrend, Raoul. "Asteroids and comets rotation curves – (909) Ulla". Geneva Observatory. http://obswww.unige.ch/~behrend/page3cou.html#000909. 

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