{{Short description|Star system in the constellation Taurus}}{{distinguish|T Tauri}} {{Starbox begin}} {{Starbox image |image= {{Location mark |image=Taurus constellation map.svg|alt=|float=center|width=280 |label=|position=right |mark=Red circle.svg|mark_width=10|mark_link=Tau Tauri |x=457|y=363 }} | caption = Location of τ Tauri (circled) }} {{Starbox observe | epoch = J2000 | constell = Taurus | ra = {{RA|04|42|14.70161}}<ref name=vanLeeuwen2007/> | dec = {{DEC|+22|57|24.9214}}<ref name=vanLeeuwen2007/> | appmag_v = 4.27<ref name=XHIP/> }} {{Starbox character | type = | class = B3V<ref name=Hoffleit1991/> + ? + A0V–A2V<ref name=Richichi1994/> + A1V<ref name=Eggleton2008/> | b-v = -0.14<ref name=Mallama2014/> | u-b = -0.57<ref name=Mallama2014/> | variable = }} {{Starbox astrometry | radial_v = +14.60<ref name=Wilson1953/> | prop_mo_ra = -2.89<ref name=vanLeeuwen2007/> | prop_mo_dec = -21.86<ref name=vanLeeuwen2007/> | parallax = 8.19 | p_error = 0.88 | parallax_footnote = <ref name=vanLeeuwen2007/> | absmag_v = -1.15<ref name=XHIP/> }} {{Starbox orbit | reference = <ref name=Petrie1961/> | primary = Aa | period_unitless = {{Val|2.956549|0.000002|u=days}} | axis = <!--Semimajor axis (in arcseconds)--> | axis_unitless = ≤ {{Convert|2176000|km|AU|disp=out}} | eccentricity = {{Val|0.051|0.019}} | periastron = {{Val|2436424.207|0.009|ul=JD|fmt=commas}} | periarg = {{Val|126.7|21.8}} | k1 = {{Val|53.6|1.0}} }} {{Starbox detail | component1 = Aa | mass = 6.4<ref name=Tetzlaff2011/> | radius = | gravity = 2.60<ref name=Wu2011/> | metal_fe = -0.51<ref name=Wu2011/> | age_gyr = | temperature = 18,700<ref name=Hohle2010/> | luminosity = 1,472<ref name=Hohle2010/> | rotational_velocity = 115<ref name=Abt2002/> }} {{Starbox catalog | names = {{odlist | name=Gaja | B=τ Tau | F=94 Tauri | BD=+22°739 | FK5=174 | HD=29763 | HIP=21881 | HR=1497 | SAO=76721 | GC=5716 | CCDM=J04422+2257AB | GSC=01830-02129 | WDS=J04422+2257A }}<ref name=SIMBAD/> }} {{Starbox reference | Simbad = tau+Tau }} {{Starbox end}}
'''Tau Tauri''', also named '''Gaja''',<ref name=IAU-CSN/> is a quadruple star system<ref name=Eggleton2008/> in the constellation Taurus. It is visible to the naked eye as a faint point of light with a combined apparent visual magnitude of 4.33.<ref name=WDS/> The distance to this system is approximately about 400 light years based on parallax.<ref name=vanLeeuwen2007/> The system is moving further from the Earth with a heliocentric radial velocity of +14.6 km/s,<ref name=Wilson1953/> and it is a member of the Taurion OB association, located between Orion and Taurus.<ref name=Buoy2015/> It is located 0.7 degree north of the ecliptic, and thus is subject to lunar occultations.<ref name=Richichi1994/>
The blue-white hued primary, component Aa, is a B-type main-sequence star with a stellar classification of B3V.<ref name=Hoffleit1991/> It was found to be a close spectroscopic binary in 1903 by American astronomers Edwin B. Frost and Walter S. Adams. The pair have an orbital period of 2.96 days and eccentricity of 0.05.<ref name=Petrie1961/> A second companion, white-hued component Ab, has magnitude 6.97 and angular separation 0.2" from the primary in a 58-year orbit.<ref name=Malkov2012/><ref name=Eggleton2008/> This is a probably A-type main-sequence star with a class of A0V–A2V.<ref name=Richichi1994/> The more distant component B is a type A1V star with magnitude 7.2 and separation 62.8".<ref name=Eggleton2008/>
==Nomenclature== ''Tau Tauri'', Latinized from ''τ Tauri'', is the star's Bayer designation. The term ''gaja(h)'' (Sanskrit: {{lang|sa|गज}}) means elephant, and is the name of a constellation from Bali (Indonesia) corresponding to Taurus, attested in the cultural calendar called ''Palelintangan''.<ref name=ASE/> The IAU Working Group on Star Names approved the name Gaja for Tau Tauri Aa (in the elephant's tusk) on 22 February 2026.<ref name=IAU-CSN/>
==See also== * 97 Tauri, named Lembu from another Balinese constellation in Taurus
==References== <references> <ref name=SIMBAD>{{cite simbad | title=tau Tau | access-date=2016-10-18 | postscript=. }}</ref>
<ref name=Petrie1961>{{cite journal | title=The spectroscopic binary Boss 1107 | last1=Petrie | first1=R. M. | last2=Ebbighausen | first2=E. G. | journal=Publications of the Dominion Astrophysical Observatory Victoria | volume=11 | pages=385–394 | date=1961 | bibcode=1961PDAO...11..385P }}</ref>
<ref name=Buoy2015>{{cite journal | title=Cosmography of OB stars in the solar neighbourhood | last1=Bouy | first1=H. | last2=Alves | first2=J. | journal=Astronomy & Astrophysics | volume=584 | id=A26 | pages=13 | date=December 2015 | doi=10.1051/0004-6361/201527058 | bibcode=2015A&A...584A..26B | doi-access=free }}</ref>
<ref name=Richichi1994>{{cite journal | title=New binary stars discovered by lunar occultations | display-authors=1 | last1=Richichi | first1=A. | last2=Calamai | first2=G. | last3=Leinert | first3=C. | journal=Astronomy and Astrophysics | volume=286 | pages=829–837 | date=June 1994 | bibcode=1994A&A...286..829R }}</ref>
<ref name=vanLeeuwen2007>{{cite journal | title=Validation of the new Hipparcos reduction | last1=Van Leeuwen | first1=F. | journal=Astronomy and Astrophysics | volume=474 | issue=2 | pages=653–664 | year=2007 | arxiv=0708.1752 | bibcode=2007A&A...474..653V | doi=10.1051/0004-6361:20078357 | s2cid=18759600 }} [http://vizier.u-strasbg.fr/viz-bin/VizieR-S?HIP%2021881 Vizier catalog entry]</ref>
<ref name=XHIP>{{cite journal | bibcode=2012AstL...38..331A | doi=10.1134/S1063773712050015 | arxiv=1108.4971 | title=XHIP: An extended hipparcos compilation | journal=Astronomy Letters | volume=38 | issue=5 | pages=331 | year=2012 | last1=Anderson | first1=E. | last2=Francis | first2=Ch. | s2cid=119257644 }} [http://vizier.u-strasbg.fr/viz-bin/VizieR-4?-source=V/137D/XHIP&HIP=21881 Vizier catalog entry]</ref>
<ref name=Hoffleit1991>{{cite journal | bibcode=1995yCat.5050....0H | title=VizieR Online Data Catalog: Bright Star Catalogue, 5th Revised Ed. (Hoffleit+, 1991) | journal=VizieR On-line Data Catalog: V/50. Originally Published in: 1964BS....C......0H | volume=5050 | last1=Hoffleit | first1=D. | last2=Warren | first2=W. H. | year=1995 }}</ref>
<ref name=Mallama2014>{{cite journal | bibcode=2014JAVSO..42..443M | title=Sloan Magnitudes for the Brightest Stars | journal=The Journal of the American Association of Variable Star Observers | volume=42 | pages=443 | last1=Mallama | first1=A. | year=2014 | issue=2 }}[http://vizier.u-strasbg.fr/viz-bin/VizieR-4?-source=J/other/JAVSO/42.443/ugriz&HD=029763 Vizier catalog entry]</ref>
<ref name=Wilson1953>{{cite journal | last=Wilson | first=R. E. | year=1953 | title=General Catalogue of Stellar Radial Velocities | journal=Carnegie Institute Washington D.C. Publication | publisher=Carnegie Institution for Science | bibcode=1953GCRV..C......0W | isbn=9780598216885 | lccn=54001336 }}</ref>
<ref name=Tetzlaff2011>{{cite journal | bibcode=2011MNRAS.410..190T | doi=10.1111/j.1365-2966.2010.17434.x | arxiv=1007.4883 | title=A catalogue of young runaway Hipparcos stars within 3 kpc from the Sun | journal=Monthly Notices of the Royal Astronomical Society | volume=410 | pages=190–200 | year=2011 | last1=Tetzlaff | first1=N. | last2=Neuhäuser | first2=R. | last3=Hohle | first3=M. M. | issue=1 | doi-access=free | s2cid=118629873 }} [http://vizier.u-strasbg.fr/viz-bin/VizieR-4?-source=J/MNRAS/410/190/table1&HIP=21881 Vizier catalog entry]</ref>
<ref name=Hohle2010>{{cite journal | bibcode=2010AN....331..349H | doi=10.1002/asna.200911355 | arxiv=1003.2335 | title=Masses and luminosities of O- and B-type stars and red supergiants | journal=Astronomische Nachrichten | volume=331 | issue=4 | pages=349 | year=2010 | last1=Hohle | first1=M.M. | last2=Neuhäuser | first2=R. | last3=Schutz | first3=B.F. | s2cid=111387483 }} [http://vizier.u-strasbg.fr/viz-bin/VizieR-4?-source=J/AN/331/349/single&HIP=21881 Vizier catalog entry]</ref>
<ref name=Abt2002>{{cite journal | bibcode=2002ApJ...573..359A | doi=10.1086/340590 | title=Rotational Velocities of B Stars | journal=The Astrophysical Journal | volume=573 | pages=359–365 | year=2002 | last1=Abt | first1=Helmut A. | last2=Levato | first2=Hugo | last3=Grosso | first3=Monica | issue=1 | doi-access=free }}</ref>
<ref name=Wu2011>{{cite journal | bibcode=2011A&A...525A..71W | doi=10.1051/0004-6361/201015014 | arxiv=1009.1491 | title=Coudé-feed stellar spectral library – atmospheric parameters | journal=Astronomy & Astrophysics | volume=525 | pages=A71 | year=2010 | last1=Wu | first1=Yue | last2=Singh | first2=H. P. | last3=Prugniel | first3=P. | last4=Gupta | first4=R. | last5=Koleva | first5=M. | s2cid=53480665 }}</ref>
<ref name=Malkov2012>{{cite journal | bibcode=2012A&A...546A..69M | doi=10.1051/0004-6361/201219774 | title=Dynamical masses of a selected sample of orbital binaries | journal=Astronomy & Astrophysics | volume=546 | pages=A69 | year=2012 | last1=Malkov | first1=O. Yu. | last2=Tamazian | first2=V. S. | last3=Docobo | first3=J. A. | last4=Chulkov | first4=D. A. | doi-access=free }} [http://vizier.u-strasbg.fr/viz-bin/VizieR-4?-source=J/A%2bA/546/A69/table1&WDS=04422%2B2257 Vizier catalog entry]</ref>
<ref name=Eggleton2008>{{cite journal | bibcode=2008MNRAS.389..869E | doi=10.1111/j.1365-2966.2008.13596.x | arxiv = 0806.2878 | title=A catalogue of multiplicity among bright stellar systems | journal=Monthly Notices of the Royal Astronomical Society | volume=389 | issue=2 | pages=869 | year=2008 | last1=Eggleton | first1=P. P. | last2=Tokovinin | first2=A. A. | doi-access=free | s2cid=14878976 }} [http://vizier.u-strasbg.fr/viz-bin/VizieR-4?-source=J/MNRAS/389/869/table1&mHR=1497 Vizier catalog entry]</ref>
<ref name=WDS>{{cite journal | bibcode=2001AJ....122.3466M | doi=10.1086/323920 | title=The 2001 US Naval Observatory Double Star CD-ROM. I. The Washington Double Star Catalog | journal=The Astronomical Journal | volume=122 | issue=6 | pages=3466 | year=2001 | last1=Mason | first1=Brian D. | last2=Wycoff | first2=Gary L. | last3=Hartkopf | first3=William I. | last4=Douglass | first4=Geoffrey G. | last5=Worley | first5=Charles E. | doi-access=free }} [http://vizier.u-strasbg.fr/viz-bin/VizieR-4?-source=B/wds/wds&WDS=04422%2B2257 Vizier catalog entry]</ref>
<ref name=ASE>{{cite web |title=Gaja (गज) |url=https://ase.exopla.net/index.php/Gaja |website=All Skies Encyclopaedia |publisher=IAU Working Group on Star Names |access-date=22 February 2026}}</ref>
<ref name=IAU-CSN>{{cite web |title=IAU Catalog of Star Names |url=https://exopla.net/star-names/modern-iau-star-names/ |access-date=22 February 2026}}</ref> </references>
{{Stars of Taurus}} <!-- Properties -->
Category:B-type main-sequence stars Category:A-type main-sequence stars Category:Spectroscopic binaries 4 <!-- Identifiers --> Category:Taurus (constellation) Tauri, Tau BD+22 0739 Tauri, 094 029763 021881 1497 Gaja