{{Short description|Variable star in Taurus}} {{Starbox begin}} {{Starbox image | image = 250px | caption = A light curve for SZ Tauri, plotted from ''TESS'' data<ref name=MAST/> }} {{Starbox observe | epoch = J2000 | constell = Taurus<ref name=Anderson_Francis_2012/> | ra = {{RA|04|37|14.778}}<ref name=GaiaEDR3/> | dec = {{DEC|+18|32|34.93}}<ref name=GaiaEDR3/> | appmag_v = {{nowrap|6.39 to 6.69}}<ref name=Klagyivik_Szabados_2009/> }} {{Starbox character | type = Supergiant | class = F5Ib-F9.5Ib<ref name=Kraft1960/> | b-v = 0.810{{±|0.025}}<ref name=Anderson_Francis_2012/> | u-b = | variable = δ Cep<ref name=Samus_et_al_2017/> }} {{Starbox astrometry | radial_v = −1.2{{±|0.2}}<ref name=Gontcharov2006/> | prop_mo_ra = −4.403 | prop_mo_dec = −5.232 | pm_footnote = <ref name=GaiaEDR3/> | parallax = 1.5741 | p_error = 0.028 | parallax_footnote = <ref name=GaiaEDR3/> | absmag_v = }} {{Starbox detail | mass = 6.1{{±|0.8}}<ref name=Marconi_et_al_2020/> | radius = 42.2{{±|3.0}}<ref name=Postma_Milone_2006/> | luminosity = 1,905<ref name=Sanwal_et_al_1989/> | gravity = 2.0–2.2<ref name=Andrievsky_et_al_2013/> | temperature = 6,015–6,420<ref name=Sanwal_et_al_1989/> | metal_fe = 0.08<ref name=Andrievsky_et_al_2013/> | rotation = | rotational_velocity = | age_myr = 69–80<ref name=Fadeyev2015/> }} {{Starbox catalog | names = {{odlist | V=SZ Tau | BD=+18 661 | GC=5621 | HD=29260 | HIP=21517 | PPM=120081 | SAO=94036 }}<ref name=SIMBAD/> }} {{Starbox reference | Simbad = SZ+Tau }} {{Starbox end}}

'''SZ Tauri''' is a variable star in the equatorial constellation of Taurus. The brightness of this star varies from an apparent visual magnitude of 6.39 down to 6.69 with a period of 3.149&nbsp;days,<ref name=Klagyivik_Szabados_2009/> which is near the lower limit of visibility to the naked eye. The distance to this star is approximately 2,070&nbsp;light years based on parallax measurements.<ref name=GaiaEDR3/> There is some indication this may be a binary system, but the evidence is inconclusive.<ref name=Kervella_et_al_2019/>

The variability of this star was announced by K. Schwarzschild in 1911 and was given a preliminary designation of 41.1910 with a period of {{val|3.1484|u=days}}.<ref name=Schwarzschild1911/><ref name=Shapley1913/> H. S. Leavitt extended the study up to 1914, producing a light curve with a period of {{val|3.1487|u=days}}.<ref name=Leavitt_Pickering_1914/> A 1916 spectral study by H. Shapley showed that the class of this pulsating Cepheid variable changed along the light curve, ranging from F7 at minimum up to A9 at peak luminosity.<ref name=Shapley1916/> Y. N. Efremov suggested in 1964 that this star may be a halo member of the NGC 1647 open cluster,<ref name=Turner1992/> located 2.2° to the northeast. However, this was later disputed based on a poor proper motion match.<ref name=Baumgardt_et_al_2000/> It was confirmed to be a classical Cepheid by W. P. Gieren in 1985.<ref name=Gieren1985/>

In the General Catalogue of Variable Stars, SZ Tau is classified as a Delta Cepheid of type DCEPS, which shows a nearly symmetric light curve with a small amplitude.<ref name=Samus_et_al_2017/> It is pulsating in the first overtone<ref name=Turner1992/> and in evolutionary terms is undergoing its second crossing of the Cepheid instability strip.<ref name=Fadeyev2015/> By 1987, four changes in the pulsation period of SZ Tau had been observed;<ref name=Trammell1987/> the pulsation rate is decreasing by −0.49&nbsp;s/yr.<ref name=Fadeyev2015/> The star is about 75<ref name=Fadeyev2015/>&nbsp;million years old with six<ref name=Marconi_et_al_2020/> times the mass of the Sun and 42<ref name=Postma_Milone_2006/> times the Sun's radius. The effective temperature, radius, and spectral type of the star vary across each pulsation cycle.<ref name=Sanwal_et_al_1989/>

== References == <references> <ref name=SIMBAD>{{cite simbad | title=SZ Tau | access-date=2022-03-10 | postscript=. | mode=cs2 }}</ref>

<ref name=GaiaEDR3>{{Cite Gaia EDR3|3409635486731094400}}</ref>

<ref name=Kervella_et_al_2019>{{citation | postscript=. | title=Multiplicity of Galactic Cepheids and RR Lyrae stars from Gaia DR2. II. Resolved common proper motion pairs | display-authors=1 | last1=Kervella | first1=Pierre | last2=Gallenne | first2=Alexandre | last3=Evans | first3=Nancy Remage | last4=Szabados | first4=Laszlo | last5=Arenou | first5=Frédéric | last6=Mérand | first6=Antoine | last7=Nardetto | first7=Nicolas | last8=Gieren | first8=Wolfgang | last9=Pietrzynski | first9=Grzegorz | journal=Astronomy & Astrophysics | volume=623 | id=A117 | pages=40 | date=March 2019 | doi=10.1051/0004-6361/201834211 | arxiv=1908.00545 | bibcode=2019A&A...623A.117K | s2cid=261941148 }}</ref>

<ref name=Baumgardt_et_al_2000>{{citation | postscript=. | title=Absolute proper motions of open clusters. I. Observational data | display-authors=1 | last1=Baumgardt | first1=H. | last2=Dettbarn | first2=C. | last3=Wielen | first3=R. | journal=Astronomy and Astrophysics Supplement | volume=146 | pages=251–258 | date=October 2000 | issue=2 | doi=10.1051/aas:2000362 | arxiv=astro-ph/0010306 | bibcode=2000A&AS..146..251B | s2cid=7180188 }}</ref>

<ref name=Gontcharov2006>{{citation | last1=Gontcharov | first1=G. A. | title=Pulkovo Compilation of Radial Velocities for 35495 Hipparcos stars in a common system | journal=Astronomy Letters | postscript=. | volume=32| issue=11| pages=759–771| date=November 2006 | doi=10.1134/S1063773706110065 | arxiv=1606.08053 | bibcode=2006AstL...32..759G | s2cid=119231169 }}</ref>

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

<ref name=Andrievsky_et_al_2013>{{citation | postscript=. | title=Barium abundances in Cepheids | display-authors=1 | last1=Andrievsky | first1=S. M. | last2=Lépine | first2=J. R. D. | last3=Korotin | first3=S. A. | last4=Luck | first4=R. E. | last5=Kovtyukh | first5=V. V. | last6=MacIel | first6=W. J. | journal=Monthly Notices of the Royal Astronomical Society | volume=428 | issue=4 | pages=3252 | year=2013 | bibcode=2013MNRAS.428.3252A | arxiv=1210.6211 | doi=10.1093/mnras/sts270 | doi-access=free}}</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=Kraft1960>{{citation | postscript=. | title=Color Excesses for Supergiants and Classical Cepheids. I. Calibration of the Gband Photometry | last=Kraft | first=Robert P. | journal=Astrophysical Journal | volume=131 | page=330 | date=March 1960 | doi=10.1086/146837 | bibcode=1960ApJ...131..330K }}</ref>

<ref name=Klagyivik_Szabados_2009>{{citation | postscript=. | last1=Klagyivik | first1=P. | last2=Szabados | first2=L. | title=Observational studies of Cepheid amplitudes. I. Period-amplitude relationships for Galactic Cepheids and interrelation of amplitudes | journal=Astronomy and Astrophysics | volume=504 | issue=3 | pages=959–972 | date=September 2009 | bibcode=2009A&A...504..959K | arxiv=0908.3561 | doi=10.1051/0004-6361/200811464 | s2cid=18283579 }}</ref>

<ref name=Samus_et_al_2017>{{citation | postscript=. | title=General catalogue of variable stars | version=GCVS 5.1 | 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 | journal=Astronomy Reports | display-authors=1 | volume=61 | issue=1 | pages=80 | year=2017 | bibcode=2017ARep...61...80S | s2cid=125853869 | doi=10.1134/S1063772917010085 }}</ref>

<ref name=Marconi_et_al_2020>{{citation | postscript=. | title=Predicted Masses of Galactic Cepheids in the Gaia Data Release 2 | last1=Marconi | first1=Marcella | last2=De Somma | first2=Giuli | last3=Ripepi | first3=Vincenzo | last4=Molinaro | first4=Roberto | last5=Musella | first5=Ilaria | last6=Leccia | first6=Silvio | last7=Moretti | first7=Maria Ida | journal=The Astrophysical Journal Letters | volume=898 | issue=1 | id=L7 | display-authors=1 | date=July 2020 | pages=L7 | doi=10.3847/2041-8213/aba12b | arxiv=2006.16610 | bibcode=2020ApJ...898L...7M | s2cid=220265392 | doi-access=free }}</ref>

<ref name=Schwarzschild1911>{{citation | postscript=. | title=Über den Lichtwechsel des Veränderlichen 41.1910 Tauri | last=Schwarzschild | first=Karl | author-link=Karl Schwarzschild | journal=Astronomische Nachrichten | language=de | volume=189 | issue=20 | pages=345–356 | date=October 1911 | doi=10.1002/asna.2101892002 | bibcode=1911AN....189..345S | url=https://zenodo.org/record/1821975 }}</ref>

<ref name=Shapley1916>{{citation | postscript=. | title=The variations in spectral type of twenty Cepheid variables | last=Shapley | first=H. | journal=Astrophysical Journal | volume=44 | pages=273–291 | date=December 1916 | doi=10.1086/142295 | bibcode=1916ApJ....44..273S }}</ref>

<ref name=Shapley1913>{{citation | postscript=. | title=Concerning the ellipsoidal variables SZ Tauri and S Antliae | last=Shapley | first=H. | author-link=Harlow Shapley | journal=Astronomische Nachrichten | volume=194 | issue=21 | pages=353–359 | date=May 1913 | doi=10.1002/asna.19131942102 | bibcode=1913AN....194..353S | url=https://zenodo.org/record/2347121 }}</ref>

<ref name=Leavitt_Pickering_1914>{{citation | postscript=. | title=Observations of SZ Tauri | last1=Leavitt | first1=Henrietta S. | author1-link=Henrietta Swan Leavitt | last2=Pickering | first2=Edward C. | author2-link= Edward Charles Pickering | journal=Harvard College Observatory Circular | volume=186 | pages=1–4 | date=November 1914 | bibcode=1914HarCi.186....1L }}</ref>

<ref name=Gieren1985>{{citation | postscript=. | title=Physical properties of the cepheids RT Aurigae and SZ Tauri | last=Gieren | first=W. P. | journal=Astronomy and Astrophysics | volume=148 | pages=138–144 | date=July 1985 | bibcode=1985A&A...148..138G }}</ref>

<ref name=Turner1992>{{citation | postscript=. | title=Galactic Clusters With Associated Cepheid Variables. III. NGC 1647 and SZ Tauri | last=Turner | first=David G. | journal=Astronomical Journal | volume=104 | page=1865 | date=November 1992 | doi=10.1086/116363 | bibcode=1992AJ....104.1865T | url=https://library2.smu.ca/handle/01/26630 }}</ref>

<ref name=Trammell1987>{{citation | postscript=. | title=The Changing Period of SZ Tauri | last=Trammell | first=Susan R. | journal=The Journal of the American Association of Variable Star Observers | volume=16 | issue=2 | pages=104–106 | date=December 1987 | bibcode=1987JAVSO..16..104T }}</ref>

<ref name=Sanwal_et_al_1989>{{citation | postscript=. | title=Spectrophotometric Study of the Cepheids DT-Cygni and SZ-Tauri | last1=Sanwal | first1=B. B. | last2=Rautela | first2=B. S. | journal=Astrophysics and Space Science | volume=151 | issue=2 | pages=209–215 | date=January 1989 | doi=10.1007/BF00648379 | bibcode=1989Ap&SS.151..209S | s2cid=119557969 }}</ref>

<ref name=Postma_Milone_2006>{{citation | postscript=. | title=Observations and Analyses of the Cepheid SZ Tauri | last1=Postma | first1=Joseph E. | last2=Milone | first2=E. F. | journal=Bulletin of the American Astronomical Society | volume=38 | page=144 | date=June 2006 | bibcode=2006AAS...208.6506P }}</ref>

<ref name=Fadeyev2015>{{citation | postscript=. | title=Evolution, pulsation and period change in the Cepheid SZ Tau | last=Fadeyev | first=Yu. A. | journal=Astronomy Letters | volume=41 | issue=11 | pages=640–645 | date=November 2015 | doi=10.1134/S1063773715110031 | arxiv=1507.04715 | bibcode=2015AstL...41..640F | s2cid=255192877 }}</ref> </references>

{{Taurus (constellation)}}

<!-- Properties --> Category:F-type supergiants Category:Classical Cepheid variables <!-- Location/Catalogues --> Category:Taurus (constellation) BD+18 661 029260 021517 Tauri, SZ Category:Population I stars