{{Short description|Vesta asteroid}} {{Use dmy dates|date=October 2019}} {{Infobox planet | minorplanet = yes | name = 1781 Van Biesbroeck | background = #D6D6D6 | image = 001781-asteroid shape model (1781) Van Biesbroeck.png | image_scale = | caption = ''Van Biesbroeck'' modeled from its lightcurve | discovery_ref = <ref name="jpldata" /> | discovered = 17 October 1906 | discoverer = A. Kopff | discovery_site = Heidelberg Obs. | mpc_name = (1781) Van Biesbroeck | alt_names = A906 UB{{·}}1954 SZ<br />1958 VP{{·}}{{mp|1969 TM|2}} | named_after = {{nowrap|George Van Biesbroeck}}<br />{{small|(astronomer)}}<ref name="springer" /> | mp_category = main-belt{{·}}Vestian<ref name="Moskovitz-2008" /> | orbit_ref = <ref name="jpldata" /> | epoch = 4 September 2017 (JD 2458000.5) | uncertainty = 0 | observation_arc = 110.55 yr (40,377 days) | aphelion = 2.6541 AU | perihelion = 2.1355 AU | semimajor = 2.3948 AU | eccentricity = 0.1083 | period = 3.71 yr (1,354 days) | mean_anomaly = 330.79° | mean_motion = {{Deg2DMS|0.2659|sup=ms}} / day | inclination = 6.9497° | asc_node = 44.630° | arg_peri = 342.83° | dimensions = {{val|8.500|0.126}}<ref name="Masiero-2012x" /><br />{{val|9}} km {{small|(estimate at 0.20)}}<ref name="h" /> | rotation = | albedo = {{val|0.203|0.023}}<ref name="Masiero-2012x" /> | spectral_type = XS<ref name="Moskovitz-2008" /> | abs_magnitude = 12.75<ref name="Moskovitz-2008" />{{·}}12.8<ref name="jpldata" /> }}

'''1781 Van Biesbroeck''' (''prov. designation'': {{mp|A906 UB}}) is a Vesta asteroid from the inner regions of the asteroid belt, approximately 8.5 kilometers in diameter. It was discovered on 17 October 1906, by German astronomer August Kopff at Heidelberg Observatory in southern Germany.<ref name="MPC-Van Biesbroeck" /> It was named after astronomer George Van Biesbroeck.<ref name="springer" />

== Orbit and classification ==

''Van Biesbroeck'' orbits the Sun in the inner main-belt at a distance of 2.1–2.7&nbsp;AU once every 3 years and 9 months (1,354 days). Its orbit has an eccentricity of 0.11 and an inclination of 7° with respect to the ecliptic.<ref name="jpldata" /> It is not known whether the member of the Vesta family of asteroids is in fact a V/J-type, or if it is an unrelated interloper, as currently assumed to be more likely.<ref name="Moskovitz-2008" /> The asteroid's observation arc begins with its official discovery observation, as no precoveries were taken, and no previous identifications were made.<ref name="MPC-Van Biesbroeck" />

== Physical characteristics ==

According to the survey carried out by NASA's Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission, ''Van Biesbroeck'' measures 8.5 kilometers in diameter, and its surface has an albedo of 0.203.<ref name="Masiero-2012x" /> A generic absolute magnitude-to-diameter conversion gives an inferred diameter between 8 and 14 kilometers, assuming an albedo in the range of 0.05 to 0.25 for an absolute magnitude of 12.8.<ref name="h" /> As of 2017, ''Van Biesbroeck''{{'}}s composition, rotation period and shape remain unknown.<ref name="jpldata" /><ref name="lcdb" />

== Naming ==

This minor planet was named after renowned Belgian–born observational astronomer George Van Biesbroeck, who naturalized as U.S. citizens in 1922. He specialized in the observation of double stars, variable stars, comets and asteroids, of which he discovered sixteen at the U.S. Yerkes Observatory in Williams Bay, Wisconsin, between 1922 and 1939.<ref name="springer" /> The official {{MoMP|1781|naming citation}} was published by the Minor Planet Center on 1 January 1974 ({{small|M.P.C. 3569}}).<ref name="DoMP-Circular-dates" />

In 1961, he published the Van Biesbroeck's star catalog of low-mass, low-luminosity stars. The mountain ''Van Biesbroeck'' near the McDonald Observatory, the lunar crater ''Van Biesbroeck'', and most notably the red dwarf Van Biesbroeck's Star, were also named in his honour. (There are very few stars named after people). The George Van Biesbroeck Prize, awarded by the American Astronomical Society for achievements in astronomy, also bears his name.

== References == {{reflist|30em|refs=

<ref name="jpldata">{{cite web |type = 2017-05-04 last obs. |title = JPL Small-Body Database Browser: 1781 Van Biesbroeck (A906 UB) |url = https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2001781 |publisher = Jet Propulsion Laboratory |accessdate = 1 July 2017}}</ref>

<ref name="springer">{{cite book |title = Dictionary of Minor Planet Names – (1781) Van Biesbroeck |last = Schmadel | first = Lutz D. |publisher = Springer Berlin Heidelberg |page = 142 |date = 2007 |isbn = 978-3-540-00238-3 |doi = 10.1007/978-3-540-29925-7_1782 |chapter = (1781) van Biesbroeck }}</ref>

<ref name="MPC-Van Biesbroeck">{{cite web |title = 1781 Van Biesbroeck (A906 UB) |work = Minor Planet Center |url = https://www.minorplanetcenter.net/db_search/show_object?object_id=1781 |accessdate = 15 May 2016}}</ref>

<ref name="DoMP-Circular-dates">{{cite book |title = Dictionary of Minor Planet Names – Addendum to Fifth Edition (2006–2008) |chapter = Appendix – Publication Dates of the MPCs |last = Schmadel |first=Lutz D. |publisher = Springer Berlin Heidelberg |page = 221 |isbn = 978-3-642-01964-7 |doi = 10.1007/978-3-642-01965-4}}</ref>

<ref name="h">{{cite web |title = Absolute Magnitude (H) |publisher = NASA/JPL |url = http://neo.jpl.nasa.gov/glossary/h.html |archive-url = https://web.archive.org/web/20010302182040/http://neo.jpl.nasa.gov/glossary/h.html |url-status = dead |archive-date = 2 March 2001 |accessdate = 15 May 2016}}</ref>

<ref name="Moskovitz-2008">{{cite journal |last = Moskovitz |first = Nicholas A. |title = The Distribution of Basaltic Asteroids in the Main Belt |journal = Icarus |volume = 198 |issue = 1 |pages = 77–90 |arxiv = 0807.3951 |date = 2008|bibcode = 2008Icar..198...77M |doi = 10.1016/j.icarus.2008.07.006 }}</ref>

<ref name="Masiero-2012x">{{Cite journal |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 |url = http://adsabs.harvard.edu/cgi-bin/bib_query?bibcode=2012ApJ...759L...8M |journal = The Astrophysical Journal Letters |volume = 759 |issue = 1 |page = 5 |bibcode = 2012ApJ...759L...8M |doi = 10.1088/2041-8205/759/1/L8 |access-date= 8 December 2016|arxiv = 1209.5794 }}</ref>

<ref name="lcdb">{{cite LCDB|number = 1781 |accessdate = 6 April 2017}}</ref>

}} <!-- end of reflist -->

== External links == * [http://www.minorplanet.info/PHP/lcdbsummaryquery.php Asteroid Lightcurve Database (LCDB)], query form ([http://www.minorplanet.info/lightcurvedatabase.html info] {{Webarchive|url=https://web.archive.org/web/20171216050541/http://www.minorplanet.info/lightcurvedatabase.html |date=16 December 2017 }}) * [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] – Observatoire de Genève, Raoul Behrend * [https://www.minorplanetcenter.net/iau/lists/NumberedMPs000001.html Discovery Circumstances: Numbered Minor Planets (1)-(5000)] – Minor Planet Center * {{AstDys|1781}} * {{JPL small body}}

{{Minor planets navigator |1780 Kippes |number=1781 |1782 Schneller}} {{Small Solar System bodies}} {{Authority control}}

{{DEFAULTSORT:Van Biesbroeck}} 001781 Category:Discoveries by August Kopff Category:Named minor planets 19061017