909 Ulla
{{Short description|Outer main-belt asteroid}}
{{Use dmy dates|date=February 2020}}
{{Infobox planet
| minorplanet = yes
| name = 909 Ulla
| background = #D6D6D6
| image = 909 Ulla orbit on 01 Jan 2009.png
| image_scale =
| caption = Orbital diagram of Ulla
| discoverer = K. Reinmuth
| discovery_site = Heidelberg Obs.
| discovered = 7 February 1919
| mpc_name = (909) Ulla
| alt_names = 1919 FA{{·}}1936 SJ
{{mp|1949 OF|1}}{{·}}1949 PW
1966 BU{{·}}1966 DM
A912 CA{{·}}A919 CA
| pronounced = {{IPA|de|ˈʊlaː|lang}}[https://www.germannames.de/wiki/Ulla (German Names)]
Classically: {{IPAc-en|'|ʌ|l|ə}}Noah Webster (1884) A Practical Dictionary of the English Language
| named_after = Ulla Ahrens
{{small|(observatory donor)}}
| mp_category = main-belt{{·}}{{small|(outer)}}
Ulla{{·}}Cybele
| epoch = 31 May 2020 (JD 2459000.5)
| uncertainty = 0
| observation_arc = 100.99 yr (36,886 d)
| aphelion = 3.8633 AU
| perihelion = 3.2217 AU
| semimajor = 3.5425 AU
| eccentricity = 0.0906
| period = 6.67 yr (2,435 d)
| mean_anomaly = 180.34°
| mean_motion = {{Deg2DMS|0.1478|sup=ms}} / day
| inclination = 18.797°
| asc_node = 146.35°
| arg_peri = 232.64°
| tisserand = 3.0250
| mean_diameter = {{plainlist|
| rotation = {{val|8.73|ul=h}}
| albedo = {{plainlist|
| spectral_type = {{plainlist|
}}
909 Ulla is a large and dark asteroid from the outermost regions of the asteroid belt, that measures approximately {{convert|116|km|mi|abbr=off|sigfig=2|sp=us}} 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. 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.
Orbit and classification
Ulla is the parent body of the Ulla family ({{small|903}}), a very small asteroid family of less than 30 known bodies. 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.
Naming
This minor planet was named after Ulla Ahrens, a daughter of a friend of the discoverer. 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 ({{small|H 50}}).
Physical characteristics
In the SMASS classification, Ulla is an X-type asteroid.
= 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 ({{small|U=3}}). Other photometric period determinations gave concurring results.
= Diameter and albedo =
According to the surveys carried out by the Infrared Astronomical Satellite IRAS and the Japanese Akari satellite, Ulla measures {{val|113.13|1.48}} and {{val|116.44|2.4}} kilometers in diameter and its surface has an albedo between {{val|0.0343|0.001}} and {{val|0.037|0.001}}. 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.
References
{{reflist|1|refs=
|type = 2020-02-04 last obs.
|title = JPL Small-Body Database Browser: 909 Ulla (A919 CA)
|url = https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2000909
|archive-url = https://web.archive.org/web/20200919122214/https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2000909
|url-status = dead
|archive-date = 19 September 2020
|publisher = Jet Propulsion Laboratory
|access-date = 24 February 2020}}
|title = Dictionary of Minor Planet Names
|last = Schmadel | first = Lutz D.
|publisher = Springer Berlin Heidelberg
|chapter = (909) Ulla
|page = 81
|date = 2007
|doi = 10.1007/978-3-540-29925-7_910
|isbn = 978-3-540-00238-3}}
|title = 909 Ulla (1919 FA)
|work = Minor Planet Center
|url = https://www.minorplanetcenter.net/db_search/show_object?object_id=909
|access-date = 7 July 2018}}
|title = Asteroids and comets rotation curves – (909) Ulla
|last = Behrend |first = Raoul
|publisher = Geneva Observatory
|url = http://obswww.unige.ch/~behrend/page3cou.html#000909
|access-date = 7 July 2018}}
|title = Asteroid 909 Ulla
|work = Small Bodies Data Ferret
|url = https://sbntools.psi.edu/ferret/SimpleSearch/results.action?targetName=909+Ulla
|access-date = 7 July 2018}}
|first1 = D. |last1 = Nesvorný
|first2 = M. |last2 = Broz
|first3 = V. |last3 = Carruba
|date = December 2014
|chapter = Identification and Dynamical Properties of Asteroid Families
|title = Asteroids IV
|pages = 297–321
|bibcode = 2015aste.book..297N
|doi = 10.2458/azu_uapress_9780816532131-ch016
|arxiv = 1502.01628
|isbn = 9780816532131|s2cid = 119280014
}}
|title = LCDB Data for (909) Ulla
|publisher = Asteroid Lightcurve Database (LCDB)
|url = http://www.minorplanet.info/PHP/generateOneAsteroidInfo.php?AstInfo=909
|access-date = 7 July 2018}}
|first1 = E. F. |last1 = Tedesco
|first2 = P. V. |last2 = Noah
|first3 = M. |last3 = Noah
|first4 = S. D. |last4 = Price
|date = October 2004
|title = IRAS Minor Planet Survey V6.0
|url = https://sbnarchive.psi.edu/pds3/iras/IRAS_A_FPA_3_RDR_IMPS_V6_0/data/diamalb.tab
|journal = NASA Planetary Data System
|volume = 12
|pages = IRAS-A-FPA-3-RDR-IMPS-V6.0
|bibcode = 2004PDSS...12.....T
|access-date = 23 February 2020}}
|display-authors = 6
|first1 = Fumihiko |last1 = Usui
|first2 = Daisuke |last2 = Kuroda
|first3 = Thomas G. |last3 = Müller
|first4 = Sunao |last4 = Hasegawa
|first5 = Masateru |last5 = Ishiguro
|first6 = Takafumi |last6 = Ootsubo
|first7 = Daisuke |last7 = Ishihara
|first8 = Hirokazu |last8 = Kataza
|first9 = Satoshi |last9 = Takita
|first10 = Shinki |last10 = Oyabu
|first11 = Munetaka |last11 = Ueno
|first12 = Hideo |last12 = Matsuhara
|first13 = Takashi |last13 = Onaka
|date = October 2011
|title = Asteroid Catalog Using Akari: AKARI/IRC Mid-Infrared Asteroid Survey
|journal = Publications of the Astronomical Society of Japan
|volume = 63
|issue = 5
|pages = 1117–1138
|bibcode = 2011PASJ...63.1117U
|doi = 10.1093/pasj/63.5.1117
|doi-access= free
}} ([http://vizier.cfa.harvard.edu/viz-bin/VizieR-5?-source=J/PASJ/63/1117/acua_v1&Num=909 online], [https://core.ac.uk/download/pdf/43545172.pdf AcuA catalog p. 153])
|first1 = M. |last1 = Gonano
|first2 = M. |last2 = di Martino
|first3 = S. |last3 = Mottola
|first4 = G. |last4 = Neukum
|date = December 1990
|title = Physical study of outer belt asteroids
|journal = Space Dust and Debris; Proceedings of the Topical Meeting of the Interdisciplinary Scientific Commission B /Meetings B2
|volume = 11
|issue = 12
|pages = 197–200
|issn = 0273-1177
|bibcode = 1991AdSpR..11l.197G
|doi = 10.1016/0273-1177(91)90563-Y}}
|first1 = Claes-Ingvar |last1 = Lagerkvist
|first2 = Anders |last2 = Erikson
|first3 = Felix |last3 = Lahulla
|first4 = Mario |last4 = De Martino
|first5 = Andreas |last5 = Nathues
|first6 = Mats |last6 = Dahlgren
|date = January 2001
|title = A Study of Cybele Asteroids. I. Spin Properties of Ten Asteroids
|journal = Icarus
|volume = 149
|issue = 1
|pages = 190–197
|bibcode = 2001Icar..149..190L
|doi = 10.1006/icar.2000.6507}}
|display-authors = 6
|first1 = M. N. |last1 = De Prá
|first2 = N. |last2 = Pinilla-Alonso
|first3 = J. M. |last3 = Carvano
|first4 = J. |last4 = Licandro
|first5 = H. |last5 = Campins
|first6 = T. |last6 = Mothé-Diniz
|first7 = J. |last7 = De León
|first8 = V. |last8 = Alí-Lagoa
|date = September 2018
|title = PRIMASS visits Hilda and Cybele groups
|journal = Icarus
|volume = 311
|pages = 35–51
|bibcode = 2018Icar..311...35D
|doi = 10.1016/j.icarus.2017.11.012
|arxiv = 1711.02071|s2cid = 119383924 }}
}}
External links
- [http://www.minorplanet.info/PHP/OneAsteroidInfo.php Lightcurve Database Query] (LCDB), at www.minorplanet.info
- [https://books.google.com/books?id=aeAg1X7afOoC&pg Dictionary of Minor Planet Names], Google books
- [http://obswww.unige.ch/~behrend/page_cou.html Asteroids and comets rotation curves, CdR] – Geneva Observatory, Raoul Behrend
- [https://www.minorplanetcenter.net/iau/lists/NumberedMPs000001.html Discovery Circumstances: Numbered Minor Planets (1)-(5000)] – Minor Planet Center
- {{AstDys|909}}
- {{JPL small body}}
{{Minor planets navigator |908 Buda |number=909 |910 Anneliese}}
{{Small Solar System bodies}}
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