View source for Astronomy:RW Tauri

{{short description|Eclipsing binary star in the constellation Taurus}}
{{Starbox begin}}
{{Starbox image
| image = [[Image:RWTauLightCurve.png|250px]]
| caption = A [[Astronomy:Light curve|light curve]] for RW Tauri, plotted from ''[[Astronomy:Transiting Exoplanet Survey Satellite|TESS]]'' data<ref name=MAST/>
}}
{{Starbox observe
 | epoch       = [[Astronomy:J2000.0|J2000.0]]
 | constell    = [[Astronomy:Taurus (constellation)|Taurus]]
 | ra          = {{RA|04|03|54.316}}<ref name=GaiaEDR3/>
 | dec         = {{DEC|28|07|33.49}}<ref name=GaiaEDR3/>
 | appmag_v    = 7.98 - 11.59<ref name=Samus_et_al_2017/>
}}
{{Starbox character
 | type        = 
 | class       = {{nowrap|B8Ve + K0IV}}<ref name=Abt_van_Biesbroeck_1959/>
 | b-v         = 0.079{{±|0.015}}<ref name=Anderson_Francis_2012/>
 | variable    = [[Astronomy:Algol variable|Algol]]&nbsp;(semidetached)<ref name=Samus_et_al_2017/>
}}
{{Starbox astrometry
 | radial_v    = 
 | prop_mo_ra  = 0.271
 | prop_mo_dec = −18.651
 | pm_footnote = <ref name=GaiaEDR3/>
 | parallax    = 3.4691
 | p_error     = 0.0428
 | parallax_footnote = <ref name=GaiaEDR3/>
 | absmag_v    = 
}}
{{Starbox orbit
 | reference   = 
 | primary     = <!--Primary name -->
 | name        = <!--Companion name-->
 | period      = <!--(P) Period (in years)-->
 | period_unitless = {{nowrap|2.7688439 d}}<ref name=Vesper_Honeycutt_1993/>
 | axis        = <!--(a) Semimajor axis (in arcseconds)-->
 | axis_unitless = {{solar radius|11.94}}<ref name=Malkov2020/>
 | eccentricity = 0.293{{±|0.037}}<ref name=Hiltner_Hardie_1949/>
 | inclination = 90<ref name=Vesper_Honeycutt_1993/>
 | node        = <!--(Ω) Longitude of node (in degrees)-->
 | periastron  = <!--(T) Periastron epoch-->
 | periarg     = 36.45{{±|5.57}}<ref name=Hiltner_Hardie_1949/>
 | periarg_primary = <!--(ω) Argument of periastron (in degrees), primary -->
 | k1          = 53.34{{±|1.74}}<ref name=Hiltner_Hardie_1949/>
 | k2          = <!-- Velocity semi-amplitude (secondary in SB2), in km/s -->
}}
{{Starbox detail
 | source       = <ref name=Malkov2020/>
 | component1   = Mass gaining star
 | mass         = 2.43
 | radius       = 2.27
 | luminosity   = 83
 | temperature  = 11,560
 | gravity      = 3.85<ref name=Vesper_Honeycutt_1993/>
 | metal_fe     = 
 | rotational_velocity = 94<ref name=Vesper_Honeycutt_1993/>
 | rotation     = 
 | age_myr      = 20.0{{±|17.2}}<ref name=Tetzlaff_et_al_2011/>
 | component2   = Donor star
 | mass2        = 0.55
 | radius2      = 3.00
 | luminosity2  = 2.81
 | temperature2 = 4,330
 | gravity2     = 
 | metal_fe2    =
 | rotational_velocity2 = 88<ref name=Vesper_Honeycutt_1993/>
}}
{{Starbox catalog
 | names = {{odlist | V=RW Tau | BD=+27°623 | HD=25487 | HIP=18972 | PPM=93202 | SAO=76418 | WDS=J04039+2808AB }}<ref name=SIMBAD/>
}}
{{Starbox reference
 | Simbad = RW+Tau
}}
{{starbox end}}

'''RW Tauri''' is a [[Astronomy:Binary star|binary star]] system in the [[Celestial equator|equatorial]] [[Astronomy:Constellation|constellation]] of [[Astronomy:Taurus (constellation)|Taurus]]. It has the designation HD&nbsp;25487 in the ''Henry Draper Catalogue'', while ''RW Tauri'' is the [[Astronomy:Variable star designation|variable star designation]]. With a peak [[Astronomy:Apparent visual magnitude|apparent visual magnitude]] of 8.05,<ref name=Anderson_Francis_2012/> it is too faint to be visible to the naked eye. The distance to this system is approximately 940&nbsp;light years based on [[Astronomy:Stellar parallax|parallax]] measurements.<ref name=GaiaEDR3/>

This system was reported as an [[Astronomy:Eclipsing binary|eclipsing binary]] by H. Shapley in 1913, who found a period of 2.769&nbsp;days and a magnitude change of 3.42 during the primary eclipse.<ref name=Shapley1913/> A [[Astronomy:Light curve|light curve]] of the eclipse was generated by H. N. Russell and associates in 1917.<ref name=Russell_et_al_1917/> Measurements by L. Binnendijk in 1941 suggested the system consisted of a hot component with a class of A0 in orbit with a cooler, larger star with a K0 class. He derived an [[Astronomy:Orbital inclination|orbital inclination]] of 86.95°{{±|0.15}}° to the line of sight from the Earth, and showed that the times of the eclipse minimum appeared to vary on a cycle.<ref name=Binnendijk1941/> Velocity measurements allowed W. A. Hiltner and R. H. Hardie to publish orbital elements for the system in 1949.<ref name=Hiltner_Hardie_1949/> Longer term observations of the system demonstrated that period variation is not periodic but occurs with abrupt changes, ruling out a third body in the system.<ref name=Šimon1996/>

In 1934, A. B. Wyse found varying emission lines in the spectrum. A. H. Joy in 1947 discovered these are paired emission lines with Doppler shifts of 350&nbsp;km/s. The lines originate from a ring around the smaller, hotter component in the system. Both the star and the ring are completely [[Astronomy:Occultation|occulted]] during an eclipse. The variation of the emission lines was confirmed, suggesting an uneven distribution of matter.<ref name=Joy1947/> The disk is the result of Roche lobe overflow from the larger component. It is no more than 1.5 times the radius of the hotter star and is rotating more slowly than orbital velocity, leading to an in-fall of gas.<ref name=Kaitchuck_Honeycutt_1982/>

This is a [[Astronomy:Semidetached binary|semi-detached binary]]<ref name=Malkov_et_al_2006/> with a [[Astronomy:Orbital period|period]] of 2.7688439&nbsp;days as of 2020,<ref name=Malkov2020/> and an [[Astronomy:Orbital eccentricity|orbital eccentricity]] of 0.3.<ref name=Hiltner_Hardie_1949/> During the primary eclipse the visual magnitude of the system decreases by 3.61 (ie. at minimum it is only 4% as bright as at maximum) while the secondary eclipse decreases the magnitude by 0.11.<ref name=Malkov_et_al_2006/> The primary eclipse is the deepest known among eclipsing binaries.<ref name=Kaitchuck_Honeycutt_1982/><ref name=Vesper_Honeycutt_1993/> The primary component is a [[Astronomy:B-type main-sequence star|B-type main-sequence star]] with a [[Astronomy:Stellar classification|stellar classification]] of B8Ve, where the 'e' indicates emission lines. The larger secondary is a more [[Astronomy:Stellar evolution|evolved]] subgiant star with a class of K0IV.<ref name=Abt_van_Biesbroeck_1959/>

In 1947, a faint, magnitude 12.5 companion was detected by A. H. Joy at an angular separation of {{val|1|ul=arcsecond|p=~}} from the pair,<ref name=Joy1947/> and this was confirmed by other observers. A 1993 study failed to detect this object,<ref name=Arévalo_et_al_1998/> but [[Engineering:Gaia (spacecraft)|Gaia]] records a magnitude 12.5 star just under {{val|2|ul="}} from RW Tauri.<ref name=dr3b/>

==References==
{{reflist|refs=

<ref name=SIMBAD>{{cite simbad
 | title=RW Tau | access-date=2022-06-20 | postscript=. | mode=cs2 }}</ref>

<ref name=GaiaEDR3>{{Cite Gaia EDR3|163742260906017024}}</ref>

<ref name=dr3b>{{cite Gaia DR3|163742265201175808}}</ref>

<ref name=Anderson_Francis_2012>{{citation
 | last1=Anderson | first1=E. | last2=Francis | first2=Ch.
 | title=XHIP: An extended hipparcos compilation
 | journal=Astronomy Letters | postscript=.
 | volume=38 | issue=5 | pages=331 | year=2012
 | bibcode=2012AstL...38..331A | arxiv=1108.4971
 | doi=10.1134/S1063773712050015 | s2cid=119257644 }}</ref>

<ref name=MAST>{{cite web
 | title=MAST: Barbara A. Mikulski Archive for Space Telescopes
 | url=https://mast.stsci.edu/portal/Mashup/Clients/Mast/Portal.html
 | publisher=Space Telescope Science Institute |access-date=8 December 2021}}</ref>

<ref name=Samus_et_al_2017>{{citation
 | display-authors=1 | last1=Samus | first1=N. N.
 | last2=Kazarovets | first2=E. V. | last3=Durlevich | first3=O. V.
 | last4=Kireeva | first4=N. N. | last5=Pastukhova | first5=E. N.
 | title=General Catalogue of Variable Stars
 | version=5.1 | journal=[[Astronomy:Astronomy Reports|Astronomy Reports]]
 | year=2017 | volume=61 | issue=1 | pages=80–88
 | bibcode=2017ARep...61...80S | doi=10.1134/S1063772917010085
 | s2cid=125853869 | postscript=. }}</ref>

<ref name=Abt_van_Biesbroeck_1959>{{citation | postscript=.
 | title=The Visual Companion of RW Tauri
 | last1=Abt | first1=Helmut A. | last2=van Biesbroeck | first2=G.
 | journal=Publications of the Astronomical Society of the Pacific
 | volume=71 | issue=421 | page=345 | date=August 1959
 | doi=10.1086/127397 | bibcode=1959PASP...71..345A | doi-access=free }}</ref>

<ref name=Hiltner_Hardie_1949>{{citation | postscript=.
 | title=The Spectrum of RW Tauri
 | last1=Hiltner | first1=W. A. | last2=Hardie | first2=R. H.
 | journal=Astrophysical Journal
 | volume=110 | page=438 | date=November 1949  <!-- The bibcode in the ninth catalogue of spectroscopic binary orbits is incorrect -->
 | doi=10.1086/145218 | bibcode=1949ApJ...110..438H }}</ref>

<ref name=Malkov_et_al_2006>{{citation
 | title=A catalogue of eclipsing variables
 | last1=Malkov | first1=O. Yu. | last2=Oblak | first2=E.
 | last3=Snegireva | first3=E. A. | last4=Torra | first4=J.
 | display-authors=1 | journal=Astronomy and Astrophysics
 | volume=446 | issue=2 | date=February 2006 | pages=785–789
 | doi=10.1051/0004-6361:20053137 | doi-access=free
 | bibcode=2006A&A...446..785M | postscript=. }}</ref>

<ref name=Shapley1913>{{citation
 | title=The orbits of eighty-seven eclipsing binaries---a summary
 | last=Shapley | first=H. | postscript=.
 | journal=Astrophysical Journal
 | volume=38 | pages=158–174 | date=September 1913
 | doi=10.1086/142018 | bibcode=1913ApJ....38..158S | hdl=2027/mdp.39015069424953 | hdl-access=free }}
See p. 163.</ref>

<ref name=Joy1947>{{citation
 | title=The Emission Lines of RW Tauri at Minimum
 | last=Joy | first=Alfred H. | postscript=.
 | journal=Publications of the Astronomical Society of the Pacific
 | volume=59 | issue=349 | page=171 | date=August 1947
 | doi= 10.1086/125933 | bibcode=1947PASP...59..171J }}</ref>

<ref name=Russell_et_al_1917>{{citation
 | title=Comparison of visual and photographic observations of eclipsing variables
 | display-authors=1 | last1=Russell | first1=H. N.
 | last2=Fowler | first2=M. | last3=Borton | first3=M. C.
 | journal=Astrophysical Journal | postscript=.
 | volume=45 | pages=306–347 | date=June 1917
 | doi=10.1086/142331 | bibcode=1917ApJ....45..306R }}</ref>

<ref name=Binnendijk1941>{{citation | postscript=.
 | title=The period and the photometric orbit of RW Tauri (Errata: 9 224)
 | last=Binnendijk | first=L.
 | journal=Bulletin of the Astronomical Institutes of the Netherlands
 | volume=9 | pages=173 | date=April 1941
 | bibcode=1941BAN.....9..173B }}</ref>

<ref name=Kaitchuck_Honeycutt_1982>{{citation | postscript=.
 | title=Time-resolved spectroscopy of the accretion disk in RW Tau
 | last1=Kaitchuck | first1=R. H. | last2=Honeycutt | first2=R. K.
 | journal=Astrophysical Journal
 | volume=258 | pages=224–235 | date=July 1982
 | doi=10.1086/160071 | bibcode=1982ApJ...258..224K }}</ref>

<ref name=Vesper_Honeycutt_1993>{{citation | postscript=.
 | title=Full-Orbit H-alpha Emission in RW Tau
 | last1=Vesper | first1=David N. | last2=Honeycutt | first2=R. K.
 | journal=Publications of the Astronomical Society of the Pacific
 | volume=105 | page=731 | date=July 1993
 | doi=10.1086/133224 | bibcode=1993PASP..105..731V | s2cid=120953483
 | doi-access=free }}</ref>

<ref name=Šimon1996>{{citation | postscript=.
 | title=Period changes of the interacting binary RW Tau
 | last=Šimon | first=V.
 | work=The Proceedings of the 27th Conference on Variable Star Research. November 10–12, 1995. Brno, Czech Republic
 | editor-first=M. | editor-last=Zejda
 | isbn=80-85882-05-1 | publication-place=Brno
 | year=1996 | page=95
 | bibcode=1996vsr..conf...95S }}</ref>

<ref name=Malkov2020>{{citation
 | title=Semidetached double-lined eclipsing binaries: Stellar parameters and rare classes
 | last=Malkov | first=Oleg Yu | postscript=.
 | journal=Monthly Notices of the Royal Astronomical Society
 | volume=491 | issue=4 | pages=5489–5497 | date=February 2020
 | doi=10.1093/mnras/stz3363 | bibcode=2020MNRAS.491.5489M | doi-access=free }}</ref>

<ref name=Arévalo_et_al_1998>{{citation | postscript=.
 | title=Infrared Photometry of the Algol system RW Tau
 | display-authors=1 | last1=Arévalo | first1=M. J.
 | last2=Lázaro | first2=C. | last3=Antonopoulou | first3=E.
 | work=Proceedings of the 20th Stellar Conference of the Czech and Slovak Astronomical Institutes. 5th - 7th November 1997. Brno, Czech Republic
 | editor-first=J. | editor-last=Dusek
 | isbn=80-85882-08-6 | publication-place=Brno
 | year=1998 | page=25 | bibcode=1998vsr..conf...25A }}</ref>

<ref name=Tetzlaff_et_al_2011>{{citation
 | title=A catalogue of young runaway Hipparcos stars within 3 kpc from the Sun
 | display-authors=1 | last1=Tetzlaff | first1=N.
 | last2=Neuhäuser | first2=R. | last3=Hohle | first3=M. M.
 | journal=Monthly Notices of the Royal Astronomical Society
 | volume=410 | issue=1 | pages=190–200 |date=January 2011
 | doi=10.1111/j.1365-2966.2010.17434.x | bibcode=2011MNRAS.410..190T
 | postscript=. | arxiv=1007.4883 | s2cid=118629873 }}</ref>

}}

==Further reading==
{{Div col|small=yes}}
*{{citation | postscript=.
 | title=The Light-time Effect in the Eclipsing Binaries with Early-type Components U CrB and RW Tau
 | last=Khaliullina | first=A. I.
 | journal=Astronomy Reports
 | volume=62 | issue=4 | pages=264–272 | date=April 2018
 | doi=10.1134/S1063772918040030 | bibcode=2018ARep...62..264K | s2cid=255191303
 }}
*{{citation | postscript=.
 | title=The Current Ephemeris of RW Tauri
 | last=Lloyd | first=Christopher
 | journal=British Astronomical Association Variable Star Section Circular
 | number=171 | pages=7–9 | date=March 2017
 | volume=171
 | bibcode=2017BAAVC.171....7L }}
*{{citation | postscript=.
 | title=Recent Period Changes in RW Tau
 | display-authors=1 | last1=Treuer | first1=Z. R.
 | last2=Londono | first2=K. | last3=van Hamme | first3=W.
 | work=International Amateur-Professional Photoelectric Photometry Communication
 | number=69 | page=23 | date=September 1997
 | volume=69
 | bibcode=1997IAPPP..69...23T }}
*{{citation | postscript=.
 | title=On the character of the orbital period changes in the interacting binary RW Tauri.
 | last=Simon | first=V.
 | journal=Astronomy and Astrophysics
 | volume=319 | pages=886–893 | date=March 1997
 | bibcode=1997A&A...319..886S }}
*{{citation | postscript=.
 | title=Out-of-Eclipse H-α Emission in RW Tau
 | last1=Vesper | first1=D. | last2=Honeycutt | first2=R. K.
 | id=119.08 | journal=Bulletin of the American Astronomical Society
 | volume=25 | page=742 | date=December 1992
 | bibcode=1992AAS...18111908V }}
*{{citation | postscript=.
 | title=Rotation Statistics of Algol-Type Binaries and Results on RY Geminorum, RW Monocerotis, and RW Tauri
 | last1=van Hamme | first1=W. | last2=Wilson | first2=R. E.
 | journal=Astronomical Journal
 | volume=100 | page=1981 | date=December 1990
 | doi=10.1086/115653 | bibcode=1990AJ....100.1981V | doi-access=free }}
*{{citation | postscript=.
 | title=Determining Rotation Rates from Lightcurves - RW-Monocerotis and RW-Tauri
 | last=van Hamme | first=W.
 | journal=Space Science Reviews
 | volume=50 | issue=1–2 | pages=373 | date=June 1989
 | doi=10.1007/BF00215976 | bibcode=1989SSRv...50..373V }}
*{{citation | postscript=.
 | title=RW Tauri as a weak W Serpentis star.
 | last1=Plavec | first1=M. J. | last2=Dobias | first2=J. J.
 | journal=Astrophysical Journal
 | volume=272 | pages=206–213 | date=September 1983
 | doi=10.1086/161280 | bibcode=1983ApJ...272..206P | doi-access=free }}
*{{citation | postscript=.
 | title=Time-resolved spectroscopy of RW Tau and X Per
 | display-authors=1 | last1=Kaitchuck | first1=R. H.
 | last2=Honeycutt | first2=R. K. | last3=Mufson | first3=S. L.
 | work="Close binary stars: observations and interpretation", IAU Symposium 88, held in Toronto, Canada, 7–10 August 1979
 | editor1-first=M. J. | editor1-last=Plavec
 | editor2-first=D. M. | editor2-last=Popper
 | editor3-first=R. K. | editor3-last=Ulrich
 | display-editors=1
 | volume=88 | pages=233–236 | year=1980
 | bibcode=1980IAUS...88..233K }}
*{{citation | postscript=.
 | title=UBVRI light curves of RW Tauri
 | last=Bookmyer | first=B. B.
 | journal=Publications of the Astronomical Society of the Pacific
 | volume=89 | pages=533–540 | date=August 1977
 | doi=10.1086/130158 | bibcode=1977PASP...89..533B | s2cid=122349148
 | doi-access=free
 }}
*{{citation | postscript=.
 | title=Determination of the Elements of Eclipsing Variables RW Tauri and U Sagittae by an Analysis of the Light Changes in the Frequency Domain
 | last=Tsouroplis | first=A. G.
 | journal=Astrophysics and Space Science
 | volume=47 | issue=2 | pages=361–373 | date=April 1977
 | doi=10.1007/BF00642844 | bibcode=1977Ap&SS..47..361T | s2cid=119572340
 }}
*{{citation | postscript=.
 | title=Variation of the Gradient and Balmer Discontinuity During the Eclipse of the Variable RW Tauri: Comparison Between Observations and Theory
 | display-authors=1 | last1=Battistini | first1=Pier Luigi
 | last2=Fracassini | first2=Massimo | last3=Pasinetti | first3=Laura E.
 | journal=Astrophysics and Space Science
 | volume=14 | issue=2 | pages=438–445 | date=December 1971
 | doi=10.1007/BF00653330 | bibcode=1971Ap&SS..14..438B | s2cid=121593493
 }}
*{{citation | postscript=.
 | title=New elements of the eclipsing variables TW Draconis, RW Tauri and KR Cygni and the influence of the rectification of the light curve upon the elements VV Ursae Maioris
 | last=Horák | first=T.
 | journal=Bulletin of the Astronomical Institute of Czechoslovakia
 | volume=17 | pages=272
 | date=1966 | bibcode=1966BAICz..17..272H }}
*{{citation | postscript=.
 | title=A new approach to the limb-darkening problem of the star RW Tauri
 | last=Kříž | first=S.
 | journal=Bulletin of the Astronomical Institute of Czechoslovakia
 | volume=16 | page=118 | date=1965
 | bibcode=1965BAICz..16..118K }}
*{{citation | postscript=.
 | title=Trajectories of particles ejected from L1 in RW Tauri
 | display-authors=1 | last1=Plavec | first1=M.
 | last2=Sehnal | first2=L. | last3=Mikuláš | first3=J.
 | journal=Bulletin of the Astronomical Institute of Czechoslovakia
 | volume=15 | page=171 | date=1964
 | bibcode=1964BAICz..15..171P }}
*{{citation | postscript=.
 | title=Spectrographic orbit of RW Tauri
 | last=Plavec | first=M.
 | journal=Bulletin of the Astronomical Institute of Czechoslovakia
 | volume=13 | page=224 | date=1962
 | bibcode=1962BAICz..13..224P }}
*{{citation | postscript=.
 | title=A Photoelectric Study of the Eclipsing Variable RW Tauri
 | last=Grant | first=Gordon
 | journal=Astrophysical Journal
 | volume=129 | page=62 | date=January 1959
 | doi=10.1086/146596 | bibcode=1959ApJ...129...62G | doi-access=free}}
{{Div col end}}

{{Stars of Taurus}}

<!-- Properties -->

[[Category:B-type main-sequence stars]]
[[Category:K-type subgiants]]
[[Category:Spectroscopic binaries]]
[[Category:Algol variables]]
<!-- Location/catalogues -->
[[Category:Taurus (constellation)]]
[[Category:Durchmusterung objects|BD+27 623]]
[[Category:Henry Draper Catalogue objects|025487]]
[[Category:Hipparcos objects|018972]]
[[Category:Objects with variable star designations|Tauri, RW]]

{{Sourceattribution|RW Tauri}}