YZ Cassiopeiae

YZ Cas
Location of YZ Cassiopeiae (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Cassiopeia[1]
A
Right ascension 00h 45m 39.0777s[2]
Declination +74° 59′ 17.063″[2]
Apparent magnitude (V) 5.653[3]
B
Right ascension 00h 45m 42,1503s[4]
Declination +74° 58′ 43.242″[4]
Apparent magnitude (V) 11.23[5]
Characteristics
A
Spectral type A2IV[6] (A1Vm + F2V[7])
U−B color index +0.07[5]
B−V color index +0.05[5]
Variable type Algol[8]
B
Spectral type F2V[9]
U−B color index +0.64[5]
B−V color index +0.94[5]
Astrometry
Radial velocity (Rv)+8.90±0.4[10] km/s
Proper motion (μ) RA: −15.07[2] mas/yr
Dec.: −22.17[2] mas/yr
Parallax (π)11.24±0.55 mas[2]
Distance103.8[9] pc
Absolute magnitude (MV)+0.251[7]
Orbit[11]
CompanionTYC 4307-2168-1
Period (P)86 580 yr
Orbit[9]
PrimaryAa
CompanionAb
Period (P)4.467 days
Semi-major axis (a)17.47 R☉[12]
Eccentricity (e)0.0
Inclination (i)88.332°
Details
Aa
Mass2.308[12] M☉
Radius2.547[12] R☉
Luminosity41.69[12] L☉
Surface gravity (log g)3.988[9] cgs
Temperature9,200[12] K
Rotational velocity (v sin i)29.2[9] km/s
Ab
Mass1.325[13] M☉
Radius1.359[12] R☉
Luminosity3.34[12] L☉
Surface gravity (log g)4.311[9] cgs
Temperature6,890[13] K
Metallicity [Fe/H]+0.10[13] dex
Rotational velocity (v sin i)15.0[9] km/s
Age490 - 550[9] Myr
Other designations
21 Cassiopeiae, HR 192, BD+74 27, HD 4161, SAO 4216, HIP 3572, GC 891, ADS 624 A, CCDM J00457+7459[14]
Database references
SIMBADdata

YZ Cassiopeiae (21 Cas) is a star system 103.8 parsecs (339 ly) away from Earth, in the constellation Cassiopeia. It comprises three stars: an eclipsing Algol-type binary and a visually fainter star about 3000 AU distant.[11] It is faintly visible to the naked eye under good observing conditions.

A light curve for YZ Cassiopeiae, plotted from TESS data[15]

The primary star in the YZ Cassiopeiae system is a white subgiant (main sequence) star of spectral type A1Vm and 2.31 solar masses[11] (M☉) with a less massive main sequence dwarf star of type F2V[3] and 1.35 M☉.[11]

In 1924, Joel Stebbins announced his discovery that the star, then known as 21 Cassiopeiae, is an eclipsing binary.[16] It was given its variable star designation, YZ Cassiopeiae, in 1925.[17] The apparent magnitude of the eclipsing binary varies from 5.65 to 6.05[3] with a period of 4.4672 days.[11] Combined, they appear to have a spectral type of A2IV.[11]

The binary has a dimmer (magnitude 9.7 according to Norton,[18] or 10.5 by SIMBAD) companion of 0.8 M☉[11] orbiting with a period of about 86 580 years.[11]

References

  1. ↑ Anderson, E.; Francis, Ch. (May 2012). "XHIP: An extended hipparcos compilation". Astronomy Letters. 38 (5): 331–346. arXiv:1108.4971. Bibcode:2012AstL...38..331A. doi:10.1134/S1063773712050015. eISSN 1562-6873. ISSN 1063-7737. S2CID 119257644.
  2. 1 2 3 4 5 van Leeuwen, F. (November 2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. S2CID 18759600.
  3. 1 2 3 Jerzy M. Kreiner, Chun-Hwey Kim, Il-Seong Nha. YZ CAS: Atlas of O-C Diagrams of Eclipsing Binary Stars
  4. 1 2 Hog, E.; Kuzmin, A.; Bastian, U.; Fabricius, C.; Kuimov, K.; Lindegren, L.; Makarov, V. V.; Roeser, S. (1998). "The TYCHO Reference Catalogue". Astronomy and Astrophysics. 335: L65. Bibcode:1998A&A...335L..65H.
  5. 1 2 3 4 5 Eggen, O. J. (1963). "Three-color photometry of the components in 228 wide double and multiple systems". Astronomical Journal. 68: 483. Bibcode:1963AJ.....68..483E. doi:10.1086/109000.
  6. ↑ Grenier, S.; Baylac, M.-O.; Rolland, L.; Burnage, R.; Arenou, F.; Briot, D.; Delmas, F.; Duflot, M.; Genty, V.; Gómez, A. E.; Halbwachs, J.-L.; Marouard, M.; Oblak, E.; Sellier, A. (1999). "Radial velocities. Measurements of 2800 B2-F5 stars for HIPPARCOS" (PDF). Astronomy and Astrophysics Supplement. 137 (3): 451. Bibcode:1999A&AS..137..451G. doi:10.1051/aas:1999489.
  7. 1 2 Bilir, S.; Ak, T.; Soydugan, E.; Soydugan, F.; Yaz, E.; Filiz Ak, N.; Eker, Z.; Demircan, O.; Helvaci, M. (2008). "New absolute magnitude calibrations for detached binaries". Astronomische Nachrichten. 329 (8): 835. arXiv:0806.1290. Bibcode:2008AN....329..835B. doi:10.1002/asna.200811002. S2CID 6131326.
  8. ↑ Samus, N. N.; Durlevich, O. V.; et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S. 1. Bibcode:2009yCat....102025S.
  9. 1 2 3 4 5 6 7 8 Pavlovski, K.; Southworth, J.; Kolbas, V.; Smalley, B. (2014). "Absolute dimensions of detached eclipsing binaries - III. The metallic-lined system YZ Cassiopeiae". Monthly Notices of the Royal Astronomical Society. 438 (1): 590–603. arXiv:1311.3482. Bibcode:2014MNRAS.438..590P. doi:10.1093/mnras/stt2229. S2CID 56144135.
  10. ↑ Gontcharov, G. A. (2006). "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system". Astronomy Letters. 32 (11): 759–771. arXiv:1606.08053. Bibcode:2006AstL...32..759G. doi:10.1134/S1063773706110065. S2CID 119231169.
  11. 1 2 3 4 5 6 7 8 Tokovinin 1997-1999. J/A+AS/124/75. Multiple star catalogue (MSC)
  12. 1 2 3 4 5 6 7 Eker, Z.; Soydugan, F.; Soydugan, E.; Bilir, S.; Yaz Gökçe, E.; Steer, I.; Tüysüz, M.; Şenyüz, T.; Demircan, O. (2015). "Main-Sequence Effective Temperatures from a Revised Mass-Luminosity Relation Based on Accurate Properties". The Astronomical Journal. 149 (4): 131. arXiv:1501.06585. Bibcode:2015AJ....149..131E. doi:10.1088/0004-6256/149/4/131. S2CID 118740259.
  13. 1 2 3 Maxted, P. F. L.; Serenelli, A. M.; Southworth, J. (2015). "Bayesian mass and age estimates for transiting exoplanet host stars". Astronomy & Astrophysics. 575: A36. arXiv:1412.7891. Bibcode:2015A&A...575A..36M. doi:10.1051/0004-6361/201425331. S2CID 54857801.
  14. ↑ "V* YZ Cas". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 26 January 2018.
  15. ↑ "MAST: Barbara A. Mikulski Archive for Space Telescopes". Space Telescope Science Institute. Retrieved 8 December 2021.
  16. ↑ Stebbins, Joel (1924). "Photo-electric photometry at the Washburn Observatory". Popular Astronomy. 32: 233–234. Bibcode:1924PA.....32..233S. Retrieved 14 January 2025.
  17. ↑ Guthnick, P.; Prager, R. (March 1925). "Benennung von neu entdeckten veränderlichen Sternen". Astronomische Nachrichten. 224 (8): 129–148. Bibcode:1925AN....224..129G. doi:10.1002/asna.19252240802. Retrieved 14 January 2025.
  18. ↑ Norton, Arthur P. (1973). Norton's Star Atlas. Gall & Inglis. p. 118. ISBN 0-85248-900-5.
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