View source for 722 Frieda

{{Short description|Bright background asteroid and slow rotator}}
{{Use dmy dates|date=June 2020}}
{{Infobox planet
| minorplanet     = yes
| name            = 722 Frieda
| background      = #D6D6D6
| image           = 000722-asteroid shape model (722) Frieda.png
| image_scale      =
| caption         = Modelled shape of ''Frieda'' from its [[lightcurve]]
| discovery_ref   = &thinsp;<ref name="MPC-object" />
| discoverer      = [[Johann Palisa|J. Palisa]]
| discovery_site  = [[Vienna Observatory|Vienna Obs.]]
| discovered      = 18 October 1911
| mpc_name        = (722) Frieda
| pronounced      = {{IPA|de|ˈfʁiːdaː|lang}}<ref name="germannames" />
| alt_names       = A911 UN{{·}}1926 GR<br />1946 SH{{·}}1911 NA
| named_after     = Frieda Hillebrand,<ref name="springer" /><br />{{small|daughter and grand-daughter of:}}<br />{{nowrap|{{Ill|Karl Hillebrand (astronomer)|lt=Karl Hillebrand|de|Karl Hillebrand (Astronom)}} {{small|(1861–1939)}}}}<br />[[Edmund Weiss]] {{small|(1837–1917)}}
| mp_category     = {{plainlist|
* [[main-belt]]&thinsp;<ref name="MPC-object" /><ref name="jpldata" />{{·}}{{small|([[Kirkwood gap|inner]])}}
* [[Background asteroid|background]]&thinsp;<ref name="AstDys-object" /><ref name="Ferret" /><ref name="Zappala-family" />
}}
| orbit_ref       = &thinsp;<ref name="jpldata" />
| epoch           = 31 May 2020 ([[Julian day|JD]] 2459000.5)
| uncertainty     = 0
| observation_arc = 109.52 [[Julian year (astronomy)|yr]] (40,002 d)
| aphelion        = 2.4858 [[Astronomical unit|AU]]
| perihelion      = 1.8575 AU
| semimajor       = 2.1717 AU
| eccentricity    = 0.1447
| period          = 3.20 yr (1,169 d)
| mean_anomaly    = 47.845[[Degree (angle)|°]]
| mean_motion     = {{Deg2DMS|0.3080|sup=ms}} / day
| inclination     = 5.6371°
| asc_node        = 45.668°
| arg_peri        = 257.23°
| mean_diameter   = {{plainlist|
* {{val|8.257|0.073|ul=km}}<ref name="Mainzer-2016" /><ref name="Masiero-2014" />
* {{val|11.43|0.23|u=km}}<ref name="AKARI" />
}}
| rotation        = {{val|131.1|0.2|ul=h}}<ref name="Polakis-2019d" />
| albedo          = {{plainlist|
* {{val|0.201|0.009}}<ref name="AKARI" />
* {{val|0.435|0.069}}<ref name="Mainzer-2016" />
}}
| spectral_type   = [[S-type asteroid|S]] {{small|(SMASS-I)}}<ref name="Ferret" />
| abs_magnitude   = {{plainlist|
* 12.10<ref name="Mainzer-2016" /><ref name="AKARI" />
* 12.30<ref name="MPC-object" /><ref name="jpldata" />}}
}}
'''722 Frieda''' (''[[Minor planet provisional designation|prov. designation]]:'' {{mp|A911 UN}} ''or'' {{mp|1911 NA}}) is a bright [[background asteroid]] and [[Slow rotator (asteroid)|slow rotator]] from the inner regions of the [[asteroid belt]]. It was discovered by Austrian astronomer [[Johann Palisa]] at the [[Vienna Observatory]] on 18 October 1911.<ref name="MPC-object" /> The stony [[S-type asteroid]] has a notably long [[rotation period]] of 131.1 hours and measures approximately {{convert|9|km|mi|abbr=off|sigfig=1|sp=us}} in diameter. It was named after Frieda Hillebrand, daughter of Austrian astronomer {{Ill|Karl Hillebrand (astronomer)|lt=Karl Hillebrand|de|Karl Hillebrand (Astronom)}} (1861–1939), and grand-daughter of [[Edmund Weiss]] (1837–1917) who had been the director of the discovering observatory.<ref name="springer" />
== Orbit and classification ==
Located in the region of the [[Flora family]] ({{small|[[FIN tbl#402|402]]}}),<ref name="Polakis-2019d" /><ref name="lcdb" /> the largest [[Asteroid family|family]] of stony asteroids, ''Frieda'' is a non-[[Asteroid family|family]] asteroid of the main belt's [[Background asteroid|background population]] when applying the [[hierarchical clustering method]] to its [[proper orbital elements]].<ref name="AstDys-object" /><ref name="Ferret" /><ref name="Zappala-family" /> It orbits the Sun in the [[Kirkwood gap|inner]] asteroid belt at a distance of 1.9–2.5&nbsp;[[Astronomical unit|AU]] once every 3 years and 2 months (1,169 days; [[semi-major axis]] of 2.17&nbsp;AU). Its orbit has an [[orbital eccentricity|eccentricity]] of 0.14 and an [[orbital inclination|inclination]] of 6[[Degree (angle)|°]] with respect to the [[ecliptic]].<ref name="jpldata" /> The body's [[observation arc]] begins at [[Heidelberg Observatory]] on 19 January 1912, or three months after its official discovery observation by [[Johann Palisa]] at [[Vienna Observatory]].<ref name="MPC-object" />
== Naming ==
According to Alexander Schnell, this [[minor planet]] was named after Frieda Hillebrand, daughter of Austrian astronomer and professor at [[Graz University]], {{Ill|Karl Hillebrand (astronomer)|lt=Karl Hillebrand|de|Karl Hillebrand (Astronom)}} (1861–1939). Frieda is also the grand-daughter of astronomer [[Edmund Weiss]] (1837–1917), who was [[Vienna Observatory#Directors|director of the Vienna Observatory]] (1877–1908) where this asteroid was discovered. The {{MoMP|722|naming citation}} was not mentioned in ''[[The Names of the Minor Planets]]'' by [[Paul Herget]] in 1955.<ref name="springer" /> Palisa also named asteroid [[794&nbsp;Irenaea]] after Frieda's mother, Irene Hillebrand (née Weiss).<ref name="springer-Irenaea" />
== Physical characteristics ==
In the SMASS-I classification by Xu (1995), ''Frieda'' is a common, stony [[S-type asteroid]].<ref name="Ferret" />
=== Rotation period ===
In April 2019, a rotational [[lightcurve]] of ''Frieda'' was obtained for the first time from 12 nights of [[Photometry (astronomy)|photometric]] observations by American amateur astronomer [[Tom Polakis]] at the Command Module Observatory {{Obscode|V02}} in Arizona. Lightcurve analysis gave a [[rotation period]] of {{val|131.1|0.2}} hours with a high brightness variation of {{val|0.45|0.05}} [[Magnitude (astronomy)|magnitude]] ({{small|[[LCDB quality code|U=2]]}}).<ref name="Polakis-2019d" />
=== Diameter and albedo ===
According to the surveys carried out by the [[NEOWISE]] mission of NASA's [[Wide-field Infrared Survey Explorer]] (WISE) and the Japanese [[Akari (satellite)|Akari satellite]], ''Frieda'' measures ({{val|8.257|0.073}}) and ({{val|11.43|0.23}}) kilometers in diameter and its surface has an [[astronomical albedo|albedo]] of ({{val|0.435|0.069}}) and ({{val|0.201|0.009}}), respectively.<ref name="Mainzer-2016" /><ref name="Masiero-2014" /><ref name="AKARI" />
The ''Collaborative Asteroid Lightcurve Link'' adopts [[Petr Pravec]]'s revised WISE-data, with an albedo of 0.2721 and a diameter of 8.794 kilometers based on an [[absolute magnitude]] of 12.31.<ref name="lcdb" /> Alternative mean-diameters published by the WISE team include ({{val|8.835|0.044|u=km}}), ({{val|9.19|0.22|u=km}}) and ({{val|10.51|2.46|u=km}}) with a corresponding albedo of ({{val|0.3309|0.3309}}), ({{val|0.252|0.025}}) and ({{val|0.23|0.10}}).<ref name="Ferret" /><ref name="lcdb" />
== References ==
{{reflist|30em|refs=
<ref name="jpldata">{{cite web
|type       = 2019-09-15 last obs.
|title      = JPL Small-Body Database Browser: 722 Frieda (A911 UN)
|url        = https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2000722
|publisher  = [[Jet Propulsion Laboratory]]
|access-date = 16 June 2020}}</ref>
<ref name="springer">{{cite book
|title      = Dictionary of Minor Planet Names
|last       = Schmadel | first = Lutz D.
|publisher  = Springer Berlin Heidelberg
|chapter    = (722) Frieda
|page       = 69
|date       = 2007
|doi        = 10.1007/978-3-540-29925-7_723
|isbn       = 978-3-540-00238-3}}</ref>
<ref name="springer-Irenaea">{{cite book
|title      = Dictionary of Minor Planet Names
|last       = Schmadel | first = Lutz D.
|publisher  = Springer Berlin Heidelberg
|chapter    = (794) Irenaea
|page       = 74
|date       = 2007
|doi        = 10.1007/978-3-540-29925-7_795
|isbn       = 978-3-540-00238-3}}</ref>
<ref name="germannames">[https://www.germannames.de/wiki/Frieda (German Names)]</ref>
<ref name="MPC-object">{{cite web
|title      = 722 Frieda (A911 UN)
|work       = Minor Planet Center
|url        = https://www.minorplanetcenter.net/db_search/show_object?object_id=722
|access-date = 16 June 2020}}</ref>
<ref name="Masiero-2014">{{cite journal
|display-authors = 6
|first1     = Joseph R. |last1 = Masiero
|first2     = T. |last2 = Grav
|first3     = A. K. |last3 = Mainzer
|first4     = C. R. |last4 = Nugent
|first5     = J. M. |last5 = Bauer
|first6     = R. |last6 = Stevenson
|first7     = S. |last7 = Sonnett
|date       = August 2014
|title      = Main-belt Asteroids with WISE/NEOWISE: Near-infrared Albedos
|journal    = The Astrophysical Journal
|volume     = 791
|issue      = 2
|page       = 11
|bibcode    = 2014ApJ...791..121M
|doi        = 10.1088/0004-637X/791/2/121
|arxiv      = 1406.6645}}</ref>
<ref name="lcdb">{{cite web
|title      = LCDB Data for (722) Frieda
|publisher  = Asteroid Lightcurve Database (LCDB)
|url        = http://www.minorplanet.info/PHP/generateOneAsteroidInfo.php?AstInfo=722
|access-date = 16 June 2020}}</ref>
<ref name="Mainzer-2016">{{cite journal
|display-authors = 6
|first1     = A. K. |last1 = Mainzer
|first2     = J. M. |last2 = Bauer
|first3     = R. M. |last3 = Cutri
|first4     = T. |last4 = Grav
|first5     = E. A. |last5 = Kramer
|first6     = J. R. |last6 = Masiero
|first7     = C. R. |last7 = Nugent
|first8     = S. M. |last8 = Sonnett
|first9     = R. A. |last9 = Stevenson
|first10    = E. L. |last10 = Wright
|date       = June 2016
|title      = NEOWISE Diameters and Albedos V1.0
|url        = https://sbnarchive.psi.edu/pds3/non_mission/EAR_A_COMPIL_5_NEOWISEDIAM_V1_0/data/neowise_mainbelt.tab
|journal    = NASA Planetary Data System
|bibcode    = 2016PDSS..247.....M
|access-date= 16 June 2020}}</ref>
<ref name="AKARI">{{cite journal
|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=722 online], [https://core.ac.uk/download/pdf/43545172.pdf AcuA catalog p. 153])</ref>
<ref name="Polakis-2019d">{{cite journal
|last1        = Polakis
|first1       = Tom
|date         = October 2019
|title        = Photometric Observations of Seventeen Minor Planets
|journal      = Minor Planet Bulletin
|url          = http://www.minorplanet.info/MPB/issues/MPB_46-4.pdf
|volume       = 46
|issue        = 4
|pages        = 400–406
|bibcode      = 2019MPBu...46..400P
|issn         = 1052-8091
|access-date  = 16 June 2020
|archive-date = 8 June 2021
|archive-url  = https://web.archive.org/web/20210608210319/http://www.minorplanet.info/MPB/issues/MPB_46-4.pdf
|url-status   = dead
}}</ref>
<ref name="Ferret">{{cite web
|title      = Asteroid 722 Frieda
|work       = Small Bodies Data Ferret
|url        = https://sbntools.psi.edu/ferret/SimpleSearch/results.action?targetName=722+Frieda
|access-date = 16 June 2020}}</ref>
<ref name="AstDys-object">{{cite web
|title      = Asteroid 722 Frieda – Proper Elements
|publisher  = AstDyS-2, Asteroids – Dynamic Site
|url        = https://newton.spacedys.com/astdys/index.php?pc=1.1.6&n=722
|access-date= 16 June 2020}}</ref>
<ref name="Zappala-family">{{cite journal
|last1      = Zappalà |first1 = V.
|last2      = Bendjoya |first2 = Ph.
|last3      = Cellino |first3 = A.
|last4      = Farinella |first4 = P.
|last5      = Froeschle |first5 = C.
|date       = 1997
|title      = Asteroid Dynamical Families
|url        = https://sbnarchive.psi.edu/pds3/non_mission/EAR_A_5_DDR_FAMILY_V4_1/data/family.tab
|journal    = NASA Planetary Data System
|pages      = EAR-A-5-DDR-FAMILY-V4.1
|access-date = 16 June 2020}}} ([https://sbn.psi.edu/pds/resource/family.html PDS main page])</ref>
}} <!-- end of reflist -->
== 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://www.minorplanetcenter.net/iau/lists/NumberedMPs000001.html Discovery Circumstances: Numbered Minor Planets (1)-(5000)] – Minor Planet Center
* {{AstDys|722}}
* {{JPL small body}}
{{Minor planets navigator |721 Tabora |number=722 |723 Hammonia}}
{{Small Solar System bodies}}
{{Authority control}}
{{DEFAULTSORT:Frieda}}
[[Category:Background asteroids|000722]]
[[Category:Discoveries by Johann Palisa]]
[[Category:Named minor planets]]
[[Category:Astronomical objects discovered in 1911|19111018]]