{{Short description|Star in the constellation Taurus}} {{Starbox begin}} {{Starbox observe |epoch=J2000 |constell=Taurus |ra={{RA|04|23|51.82553}}<ref name=HIP>{{cite journal|title=Validation of the new Hipparcos reduction|url=http://www.aanda.org/index.php?option=com_article&access=bibcode&Itemid=129&bibcode=2007A%2526A...474..653VFUL|author=van Leeuwen, F.|display-authors=etal|journal=Astronomy and Astrophysics|volume=474|issue=2|pages=653–664|date=2007|arxiv=0708.1752|bibcode=2007A&A...474..653V|doi=10.1051/0004-6361:20078357|s2cid = 18759600}}</ref> |dec={{DEC|+09|27|39.4939}}<ref name=HIP/> |appmag_v=5.098<ref name=TYC2>{{cite journal|title=The Tycho-2 catalogue of the 2.5 million brightest stars|author=Høg, E.|display-authors=etal|date=2000|journal=Astronomy and Astrophysics|volume=355|pages=L27–L30|bibcode=2000A&A...355L..27H}}</ref> (5.8 / 5.9)<ref name=ORB6/> }} {{Starbox character |class=A3V + A4V<ref name=Christy>{{cite journal|bibcode=1969PASP...81..643C|doi=10.1086/128831|title=MK Classification of 142 Visual Binaries|journal=Publications of the Astronomical Society of the Pacific|volume=81|page=643|year=1969|last1=Christy|first1=James W.|last2=Walker|first2=R. L. Jr.|issue=482|doi-access=free}}</ref> |b-v=+0.07<ref name=EgUBV>{{cite journal|author1=Mermilliod, J.-C.|title=Compilation of Eggen's UBV data, transformed to UBV (unpublished)|journal=Catalogue of Eggen's UBV Data|url=http://cdsads.u-strasbg.fr/cgi-bin/nph-bib_query?1986EgUBV........0M&db_key=AST&nosetcookie=1|date=1986|bibcode= 1986EgUBV........0M}}</ref> |u-b=+0.10<ref name=EgUBV/> }} {{Starbox astrometry |radial_v={{val|-8.70|1}}<ref>{{cite journal|title=Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system|author=Gontcharov, G. A.|date=2006|journal=Astronomy Letters|volume=32|issue=11|pages=759–771|bibcode=2006AstL...32..759G|doi=10.1134/S1063773706110065|arxiv=1606.08053|s2cid=119231169}}</ref> |prop_mo_ra=−20.32<ref name=HIP/> |prop_mo_dec=−5.32<ref name=HIP/> |parallax=8.24 |p_error=0.31 |parallax_footnote=<ref name=HIP/> |absmag_v=−0.32<ref name=xhip>{{cite journal | last1=Anderson | first1=E. | last2=Francis | first2=Ch. | title=XHIP: An extended hipparcos compilation | journal=Astronomy Letters | volume=38 | issue=5 | page=331 | year=2012 | bibcode=2012AstL...38..331A | arxiv=1108.4971 | doi=10.1134/S1063773712050015 | s2cid=119257644 }}</ref> }} {{Starbox orbit |reference=<ref name=ORB6>{{cite web|url=http://www.usno.navy.mil/USNO/astrometry/optical-IR-prod/wds/orb6|title=Sixth Catalog of Orbits of Visual Binary Stars|publisher=United States Naval Observatory|access-date=13 August 2017|archive-date=1 August 2017|archive-url=https://web.archive.org/web/20170801102553/http://www.usno.navy.mil/USNO/astrometry/optical-IR-prod/wds/orb6}}</ref> |period=54.77 |axis=0.188 |inclination=34.2 |node=239.8 |periastron=1937.24 |eccentricity=0.720 |periarg=332.0 }} {{Starbox detail |component1=66 Tau A |mass=2.89<ref name=Cvetkovic>{{cite journal|last1=Cvetkovic, Z.|last2=Ninkovic, S.|title=On the Component Masses of Visual Binaries|journal=Serbian Astronomical Journal|volume=180|issue=180|pages=71–80|date=2010|doi=10.2298/SAJ1080071C|bibcode=2010SerAJ.180...71C|doi-access=free}}</ref><ref group=note name=cvetkovic>Cvetkovic ''et al.'' gives two possible mass sums: {{solar mass|2.89 / 2.76}} or {{solar mass|2.88 / 2.77}}.</ref> |rotational_velocity=81<ref name=Royer>{{cite journal|bibcode=2007A&A...463..671R|doi=10.1051/0004-6361:20065224|arxiv=astro-ph/0610785|title=Rotational velocities of A-type stars|journal=Astronomy and Astrophysics|volume=463|issue=2|page=671|year=2007|last1=Royer|first1=F.|last2=Zorec|first2=J.|last3=Gómez|first3=A. E.|s2cid=18475298}}</ref> |component2=66 Tau B |mass2=2.76<ref name=Cvetkovic/><ref group=note name=cvetkovic/> }} {{Starbox catalog |names={{odlist|B=r Tau|BD=+09°570|HD=27820|HIP=20522|HR=1381|SAO=111791}} }} {{Starbox reference |Simbad=66+Tau }} {{Starbox end}} '''66 Tauri''', also known as '''r Tauri''', is a binary star in the constellation of Taurus. The combined apparent magnitude of the system is 5.098,<ref name=TYC2/> with the magnitudes of the two components being 5.8 and 5.9, respectively.<ref name=ORB6/> Parallax measurements by Hipparcos put 66 Tauri at some 400 light-years (121 parsecs) away.<ref name=HIP/>
This is a visual binary where the positions of the two stars are tracked over time, and used to calculate an orbit. The two stars orbit each other every 55 years.<ref name=ORB6/> Their orbit is fairly eccentric, at 0.720, and the two stars are separated by {{val|0.188|ul="}} on average.<ref name=ORB6/> Both stars are A-type main-sequence stars with similar masses.<ref name=Cvetkovic/>
==Notes== {{reflist|group=note}}
==References== {{Reflist}}
{{Stars of Taurus}}
Category:Taurus (constellation) Tauri, r Tauri, 066 Category:A-type main-sequence stars Category:Binary stars Category:Durchmusterung objects 027820 1381 020522