Astronomy:SZ Tauri

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SZ Tauri
SZTauLightCurve.png
A light curve for SZ Tauri, plotted from TESS data[1]
Observation data
Equinox J2000.0]] (ICRS)
Constellation Taurus
Right ascension  04h 37m 14.778s[2]
Declination +18° 32′ 34.93″[2]
Apparent magnitude (V) 6.39 to 6.69[3]
Characteristics
Evolutionary stage Supergiant
Spectral type F5Ib-F9.5Ib[4]
B−V color index 0.810±0.025[5]
Variable type δ Cep[6]
Astrometry
Radial velocity (Rv)−1.2±0.2[7] km/s
Proper motion (μ) RA: −4.403[2] mas/yr
Dec.: −5.232[2] mas/yr
Parallax (π)1.5741 ± 0.028[2] mas
Distance2,070 ± 40 ly
(640 ± 10 pc)
Details
Mass6.1±0.8[8] M☉
Radius42.2±3.0[9] R☉
Luminosity1,905[10] L☉
Surface gravity (log g)2.0–2.2[11] cgs
Temperature6,015–6,420[10] K
Metallicity [Fe/H]0.08[11] dex
Age69–80[12] Myr
Other designations
SZ Tau, BD+18 661, GC 5621, HD 29260, HIP 21517, SAO 94036, PPM 120081[13]
Database references
SIMBADdata

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 days,[3] which is near the lower limit of visibility to the naked eye. The distance to this star is approximately 2,070 light years based on parallax measurements.[2] There is some indication this may be a binary system, but the evidence is inconclusive.[14]

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 3.1484 d.[15][16] H. S. Leavitt extended the study up to 1914, producing a light curve with a period of 3.1487 d.[17] 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.[18] Y. N. Efremov suggested in 1964 that this star may be a halo member of the NGC 1647 open cluster,[19] located 2.2° to the northeast. However, this was later disputed based on a poor proper motion match.[20] It was confirmed to be a classical Cepheid by W. P. Gieren in 1985.[21]

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.[6] It is pulsating in the first overtone[19] and in evolutionary terms is undergoing its second crossing of the Cepheid instability strip.[12] By 1987, four changes in the pulsation period of SZ Tau had been observed;[22] the pulsation rate is decreasing by −0.49 s/yr.[12] The star is about 75[12] million years old with six[8] times the mass of the Sun and 42[9] times the Sun's radius. The effective temperature, radius, and spectral type of the star vary across each pulsation cycle.[10]

References

  1. ↑ "MAST: Barbara A. Mikulski Archive for Space Telescopes". Space Telescope Science Institute. https://mast.stsci.edu/portal/Mashup/Clients/Mast/Portal.html. 
  2. ↑ 2.0 2.1 2.2 2.3 2.4 Brown, A. G. A. (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics 649: A1. doi:10.1051/0004-6361/202039657. Bibcode: 2021A&A...649A...1G.  Gaia EDR3 record for this source at VizieR.
  3. ↑ 3.0 3.1 Klagyivik, P.; Szabados, L. (September 2009), "Observational studies of Cepheid amplitudes. I. Period-amplitude relationships for Galactic Cepheids and interrelation of amplitudes", Astronomy and Astrophysics 504 (3): 959–972, doi:10.1051/0004-6361/200811464, Bibcode: 2009A&A...504..959K. 
  4. ↑ Kraft, Robert P. (March 1960), "Color Excesses for Supergiants and Classical Cepheids. I. Calibration of the Gband Photometry", Astrophysical Journal 131: 330, doi:10.1086/146837, Bibcode: 1960ApJ...131..330K. 
  5. ↑ Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters 38 (5): 331, doi:10.1134/S1063773712050015, Bibcode: 2012AstL...38..331A. 
  6. ↑ 6.0 6.1 Samus', N. N et al. (2017), "General catalogue of variable stars", Astronomy Reports, GCVS 5.1 61 (1): 80, doi:10.1134/S1063772917010085, Bibcode: 2017ARep...61...80S. 
  7. ↑ Gontcharov, G. A. (November 2006), "Pulkovo Compilation of Radial Velocities for 35495 Hipparcos stars in a common system", Astronomy Letters 32 (11): 759–771, doi:10.1134/S1063773706110065, Bibcode: 2006AstL...32..759G. 
  8. ↑ 8.0 8.1 Marconi, Marcella et al. (July 2020), "Predicted Masses of Galactic Cepheids in the Gaia Data Release 2", The Astrophysical Journal Letters 898 (1): L7, doi:10.3847/2041-8213/aba12b, L7, Bibcode: 2020ApJ...898L...7M. 
  9. ↑ 9.0 9.1 Postma, Joseph E.; Milone, E. F. (June 2006), "Observations and Analyses of the Cepheid SZ Tauri", Bulletin of the American Astronomical Society 38: 144, Bibcode: 2006AAS...208.6506P. 
  10. ↑ 10.0 10.1 10.2 Sanwal, B. B.; Rautela, B. S. (January 1989), "Spectrophotometric Study of the Cepheids DT-Cygni and SZ-Tauri", Astrophysics and Space Science 151 (2): 209–215, doi:10.1007/BF00648379, Bibcode: 1989Ap&SS.151..209S. 
  11. ↑ 11.0 11.1 Andrievsky, S. M. et al. (2013), "Barium abundances in Cepheids", Monthly Notices of the Royal Astronomical Society 428 (4): 3252, doi:10.1093/mnras/sts270, Bibcode: 2013MNRAS.428.3252A. 
  12. ↑ 12.0 12.1 12.2 12.3 Fadeyev, Yu. A. (November 2015), "Evolution, pulsation and period change in the Cepheid SZ Tau", Astronomy Letters 41 (11): 640–645, doi:10.1134/S1063773715110031, Bibcode: 2015AstL...41..640F. 
  13. ↑ "SZ Tau". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=SZ+Tau. 
  14. ↑ Kervella, Pierre et al. (March 2019), "Multiplicity of Galactic Cepheids and RR Lyrae stars from Gaia DR2. II. Resolved common proper motion pairs", Astronomy & Astrophysics 623: 40, doi:10.1051/0004-6361/201834211, A117, Bibcode: 2019A&A...623A.117K. 
  15. ↑ "Über den Lichtwechsel des Veränderlichen 41.1910 Tauri" (in de), Astronomische Nachrichten 189 (20): 345–356, October 1911, doi:10.1002/asna.2101892002, Bibcode: 1911AN....189..345S, https://zenodo.org/record/1821975. 
  16. ↑ "Concerning the ellipsoidal variables SZ Tauri and S Antliae", Astronomische Nachrichten 194 (21): 353–359, May 1913, doi:10.1002/asna.19131942102, Bibcode: 1913AN....194..353S, https://zenodo.org/record/2347121. 
  17. ↑ "Observations of SZ Tauri", Harvard College Observatory Circular 186: 1–4, November 1914, Bibcode: 1914HarCi.186....1L. 
  18. ↑ Shapley, H. (December 1916), "The variations in spectral type of twenty Cepheid variables", Astrophysical Journal 44: 273–291, doi:10.1086/142295, Bibcode: 1916ApJ....44..273S. 
  19. ↑ 19.0 19.1 Turner, David G. (November 1992), "Galactic Clusters With Associated Cepheid Variables. III. NGC 1647 and SZ Tauri", Astronomical Journal 104: 1865, doi:10.1086/116363, Bibcode: 1992AJ....104.1865T, http://library2.smu.ca/handle/01/26630. 
  20. ↑ Baumgardt, H. et al. (October 2000), "Absolute proper motions of open clusters. I. Observational data", Astronomy and Astrophysics Supplement 146 (2): 251–258, doi:10.1051/aas:2000362, Bibcode: 2000A&AS..146..251B. 
  21. ↑ Gieren, W. P. (July 1985), "Physical properties of the cepheids RT Aurigae and SZ Tauri", Astronomy and Astrophysics 148: 138–144, Bibcode: 1985A&A...148..138G. 
  22. ↑ Trammell, Susan R. (December 1987), "The Changing Period of SZ Tauri", The Journal of the American Association of Variable Star Observers 16 (2): 104–106, Bibcode: 1987JAVSO..16..104T. 



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