894 Erda
{{Short description|Main-belt asteroid}}
{{Use dmy dates|date=February 2020}}
{{Infobox planet
| minorplanet = yes
| name = 894 Erda
| background = #D6D6D6
| image =
| image_size =
| caption =
| discoverer = M. F. Wolf
| discovery_site = Heidelberg Obs.
| discovered = 4 June 1918
| mpc_name = (894) Erda
| alt_names = A918 LA{{·}}1973 QB
A907 JC{{·}}1907 JC
A912 HD{{·}}1912 HD
1918 DT
| pronounced =
| named_after = Erda, goddess in Wagner's Der Ring des Nibelungen
{{small|(Norse mythology)}}
| mp_category = main-belt{{·}}{{small|(outer)}}
background
| epoch = 31 May 2020 (JD 2459000.5)
| uncertainty = 0
| observation_arc = 112.73 yr (41,173 d)
| aphelion = 3.4642 AU
| perihelion = 2.7752 AU
| semimajor = 3.1197 AU
| eccentricity = 0.1104
| period = 5.51 yr (2,013 d)
| mean_anomaly = 150.20°
| mean_motion = {{Deg2DMS|0.1789|sup=ms}} / day
| inclination = 12.733°
| asc_node = 190.61°
| arg_peri = 116.33°
| mean_diameter = {{plainlist|
| rotation = {{val|4.6897|0.0003|ul=h}}
| albedo = {{plainlist|
| spectral_type = X {{small|(S3OS2)}}
}}
894 Erda (prov. designation: {{mp|A918 LA}} or {{mp|1918 DT}}) is a bright background asteroid from the outer regions of the asteroid belt. It was discovered on 4 June 1918, by German astronomer Max Wolf at the Heidelberg-Königstuhl State Observatory. The X-type asteroid has a short rotation period of 4.7 hours and measures approximately {{convert|37|km|mi|abbr=off|sigfig=2|sp=us}} in diameter. It was likely named after a character in Wagner's Der Ring des Nibelungen, "Erda", who is the goddess of wisdom, fate and Earth, borrowed from the Norse sagas, and referring to both Urðr and Jörð in Norse mythology.
Orbit and classification
Erda is a non-family asteroid of the main belt's background population when applying the hierarchical clustering method to its proper orbital elements. It orbits the Sun in the outer main-belt at a distance of 2.8–3.5 AU once every 5 years and 6 months (2,013 days; semi-major axis of 3.12 AU). Its orbit has an eccentricity of 0.11 and an inclination of 13° with respect to the ecliptic. On 14 May 1907, the body's observation arc begins as {{mp|A907 JC}} ({{mp|1907 JC }}) at Heidelberg; just two nights after its first observation, and more than 11 years prior to its official discovery observation.
Naming
According to The Names of the Minor Planets by Paul Herget in 1955, and adopted by Lutz Schmadel in the Dictionary of Minor Planet Names, this minor planet was named after the Norse goddess described as the "incarnation of the nature", and as "a seer who knows the origin and the destination of all things" ({{small|H 87}}).
The discoverer, Max Wolf, likely adopted the name from Wagner's opera cycle Der Ring des Nibelungen, which is loosely based on figures from the Norse sagas. In Wagner's Ring, the character {{Ill|Erda (Wagner)|de}}, named after the Old High German word for "Earth", is the goddess of wisdom, fate and Earth. She is the world's wisest woman, the mother of the three Norns and of the valkyrie (shieldmaid) Brunhild, whose father is the norse chief god Odin (Wotan). Wagner, in turn, adopted the name from the treatise Deutsche Mythologie by Jacob Grimm (1785–1863) and other sources. Erda combines attributes of both, Urðr (wisdom and fate) and Jörð (the personification of Earth).
Physical characteristics
In both the Tholen- and SMASS-like taxonomy of the Small Solar System Objects Spectroscopic Survey (S3OS2), Erda is an X-type asteroid.
= Rotation period =
In June 2006, a rotational lightcurve of Erda was obtained from photometric observations by David Higgins at Hunters Hill Observatory {{Obscode|E14}}, Australia, and by Rui Gonçalves at Linhaceira Observatory {{Obscode|938}} in Portugal. Lightcurve analysis gave a well-defined rotation period of {{val|4.6897|0.0003}} hours with a brightness variation of {{val|0.27|0.02}} magnitude, significantly higher than previous observations had measured ({{small|U=3}}). The observers also found no indication of a previously speculated companion.
The result supersedes observations from July 2001, when both Robert Stephens and Laurent Bernasconi determined a period of {{val|4.69|0.01}} and {{val|4.69|0.05}} hours with an amplitude of {{val|0.05|0.01}} and {{val|0.06|0.03}} magnitude, respectively.
= Diameter and albedo =
According to the survey carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer (WISE), the Infrared Astronomical Satellite IRAS, and the Japanese Akari satellite, Erda measures ({{val|28.309|1.544}}), ({{val|36.54|1.8}}) and ({{val|37.84|0.45}}) kilometers in diameter and its surface has an albedo of ({{val|0.319|0.060}}), ({{val|0.2300|0.025}}) and ({{val|0.232|0.007}}), respectively. The Collaborative Asteroid Lightcurve Link derives an albedo of 0.1942 and a diameter of 36.26 kilometers based on an absolute magnitude of 9.6. An alternative mean-diameter measurement published by the WISE team gives ({{val|51.074|1.760|u=km}}) with an albedo of ({{val|0.120|0.007}}). On 17 April 2010, an asteroid occultation gave a best-fit ellipse dimension of 36.00 × 36.0 kilometers, while a second observation on 15 September 2014, measured an ellipse of 38.00 × 38.0 kilometers These timed observations are taken when the asteroid passes in front of a distant star.
References
{{reflist|30em|refs=
|type = 2020-02-01 last obs.
|title = JPL Small-Body Database Browser: 894 Erda (A918 LA)
|url = https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2000894
|publisher = Jet Propulsion Laboratory
|access-date = 25 February 2020}}
|title = Dictionary of Minor Planet Names
|url = https://archive.org/details/dictionaryminorp00schm
|url-access = limited
|last = Schmadel | first = Lutz D.
|publisher = Springer Berlin Heidelberg
|chapter = (894) Erda
|pages = [https://archive.org/details/dictionaryminorp00schm/page/n93 80]–81
|date = 2007
|doi = 10.1007/978-3-540-29925-7_895
|isbn = 978-3-540-00238-3}}
|title = 894 Erda (A918 LA)
|work = Minor Planet Center
|url = https://www.minorplanetcenter.net/db_search/show_object?object_id=894
|access-date = 25 February 2020}}
|title = Asteroids and comets rotation curves – (894) Erda
|last = Behrend |first = Raoul
|publisher = Geneva Observatory
|url = http://obswww.unige.ch/~behrend/page3cou.html#000894
|access-date = 25 February 2020}}
|display-authors = 6
|first1 = Joseph R. |last1 = Masiero
|first2 = A. K. |last2 = Mainzer
|first3 = T. |last3 = Grav
|first4 = J. M. |last4 = Bauer
|first5 = R. M. |last5 = Cutri
|first6 = C. |last6 = Nugent
|first7 = M. S. |last7 = Cabrera
|date = November 2012
|title = Preliminary Analysis of WISE/NEOWISE 3-Band Cryogenic and Post-cryogenic Observations of Main Belt Asteroids
|journal = The Astrophysical Journal Letters
|volume = 759
|issue = 1
|page = 5
|bibcode = 2012ApJ...759L...8M
|doi = 10.1088/2041-8205/759/1/L8
|arxiv = 1209.5794
}}
|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=
}} ([http://vizier.cfa.harvard.edu/viz-bin/VizieR-5?-source=J/PASJ/63/1117/acua_v1&Num=894 online], [https://core.ac.uk/download/pdf/43545172.pdf AcuA catalog p. 153])
|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 = 25 February 2020}}
|title = LCDB Data for (894) Erda
|publisher = Asteroid Lightcurve Database (LCDB)
|url = http://www.minorplanet.info/PHP/generateOneAsteroidInfo.php?AstInfo=894
|access-date = 25 February 2020}}
|last1 = Higgins |first1 = David
|last2 = Goncalves |first2 = Rui M. D.
|date = March 2007
|title = Asteroid Lightcurve Analysis at Hunters Hill Observatory and Collaborating Stations - June-September 2006
|journal = Minor Planet Bulletin
|url = http://www.minorplanet.info/MPB/issues/MPB_34-1.pdf
|volume = 34
|issue = 1
|pages = 16–18
|bibcode = 2007MPBu...34...16H
|issn = 1052-8091}}
|last1 = Stephens
|first1 = R. D.
|date = March 2002
|title = Photometry of 866 Fatme, 894 Erda, 1108 Demeter, and 3443 Letsungdao
|journal = Minor Planet Bulletin
|url = http://www.minorplanet.info/MPB/issues/MPB_29-1.pdf
|volume = 29
|issue = 1
|pages = 2–3
|bibcode = 2002MPBu...29....2S
|access-date = 25 February 2020
|archive-date = 4 October 2021
|archive-url = https://web.archive.org/web/20211004052909/http://www.minorplanet.info/MPB/issues/MPB_29-1.pdf
|url-status = dead
}}
|title = Asteroid 894 Erda
|work = Small Bodies Data Ferret
|url = https://sbntools.psi.edu/ferret/SimpleSearch/results.action?targetName=894+Erda
|access-date = 25 February 2020}}
|title = Asteroid 894 Erda – Proper Elements
|publisher = AstDyS-2, Asteroids – Dynamic Site
|url = https://newton.spacedys.com/astdys/index.php?pc=1.1.6&n=894
|access-date= 25 February 2020}}
|first1 = D. |last1 = Lazzaro
|first2 = C. A. |last2 = Angeli
|first3 = J. M. |last3 = Carvano
|first4 = T. |last4 = Mothé-Diniz
|first5 = R. |last5 = Duffard
|first6 = M. |last6 = Florczak
|date = November 2004
|title = S3OS2: the visible spectroscopic survey of 820 asteroids
|url = http://sirrah.troja.mff.cuni.cz/yarko-site/tmp/eos/NEW/spectral_type_figure/s3os2.pdf
|journal = Icarus
|volume = 172
|issue = 1
|pages = 179–220
|bibcode = 2004Icar..172..179L
|doi = 10.1016/j.icarus.2004.06.006
|access-date= 25 February 2020}}
}}
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
- [http://www.minorplanetcenter.net/iau/lists/NumberedMPs000001.html Discovery Circumstances: Numbered Minor Planets (1)-(5000)] – Minor Planet Center
- {{AstDys|894}}
- {{JPL small body}}
{{Minor planets navigator |893 Leopoldina |number=894 |895 Helio}}
{{Small Solar System bodies}}
{{Authority control}}
{{DEFAULTSORT:Erda}}