YZ Cassiopeiae

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YZ Cas
Cassiopeia constellation map.svg
Red circle.svg

Location of YZ Cassiopeiae (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Cassiopeia
Right ascension 00h 45m 39.0777s[1]
Declination +74° 59′ 17.063″[1]
Apparent magnitude (V) 5.653[2]
Right ascension 00h 45m 42,1503s[3]
Declination +74° 58′ 43.242″[3]
Apparent magnitude (V) 11.23[4]
Spectral type A2IV[5] (A1Vm + F2V[6])
U−B color index +0.07[4]
B−V color index +0.05[4]
Variable type Algol[7]
Spectral type G0V[8]
U−B color index +0.64[4]
B−V color index +0.94[4]
Radial velocity (Rv) +8.90±0.4[9] km/s
Proper motion (μ) RA: −15.07[1] mas/yr
Dec.: −22.17[1] mas/yr
Parallax (π) 11.24 ± 0.55[1] mas
Distance 103.8[10] pc
Absolute magnitude (MV) +0.251[6]
Companion TYC 4307-2168-1
Period (P) 86 580 yr
Primary Aa
Companion Ab
Period (P) 4.467 days[10]
Semi-major axis (a) 17.47 R[12]
Eccentricity (e) 0.0[10]
Inclination (i) 88.332[10]°
Mass 2.308[12] M
Radius 2.547[12] R
Luminosity 41.69[12] L
Surface gravity (log g) 3.988[10] cgs
Temperature 9,200[12] K
Rotational velocity (v sin i) 29.2[10] km/s
Mass 1.325[13] M
Radius 1.359[12] R
Luminosity 3.34[12] L
Surface gravity (log g) 4.311[10] cgs
Temperature 6.890[13] K
Rotational velocity (v sin i) 15.0[10] km/s
Age 490 - 550[10] Myr
Other designations
21 Cassiopeiae, HR 192, BD+74 27, HD 4161, SAO 4216, HIP 3572, GC 891, ADS 624 A, CCDM J00457+7459
Database references

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]

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[2] and 1.35 M.[11] The apparent magnitude of the eclipsing binary varies from 5.65 to 6.05[2] 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,[14] or 10.5 by SIMBAD) companion of 0.8 M[11] orbiting with a period of about 86 580 years.[11]


  1. ^ a b c d e van Leeuwen, F. (November 2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv:0708.1752free to read. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. 
  2. ^ a b c Jerzy M. Kreiner, Chun-Hwey Kim, Il-Seong Nha. YZ CAS: Atlas of O-C Diagrams of Eclipsing Binary Stars
  3. ^ a b 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. 
  4. ^ a b c d e 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. 
  5. ^ 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". Astronomy and Astrophysics Supplement. 137 (3): 451. Bibcode:1999A&AS..137..451G. doi:10.1051/aas:1999489. 
  6. ^ a b 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:0806.1290free to read. Bibcode:2008AN....329..835B. doi:10.1002/asna.200811002. 
  7. ^ 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. 
  8. ^ Tamazian, V. S.; Docobo, J. A.; Chavushyan, V. H.; Vlasyuk, V. V. (1997). "Optical Spectra of Some Visual Binaries with Variable Component". Visual Double Stars : Formation. Astrophysics and Space Science Library. 223: 27. Bibcode:1997ASSL..223...27T. doi:10.1007/978-94-009-1477-3_4. ISBN 978-94-010-7161-1. 
  9. ^ Gontcharov, G. A. (2006). "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system". Astronomy Letters. 32 (11): 759. Bibcode:2006AstL...32..759G. doi:10.1134/S1063773706110065. 
  10. ^ a b c d e f g h i 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: 590. arXiv:1311.3482free to read. Bibcode:2014MNRAS.438..590P. doi:10.1093/mnras/stt2229. 
  11. ^ a b c d e f g h Tokovinin 1997-1999. J/A+AS/124/75. Multiple star catalogue (MSC)
  12. ^ a b c d e f g 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. Bibcode:2015AJ....149..131E. doi:10.1088/0004-6256/149/4/131. 
  13. ^ a b 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:1412.7891free to read. Bibcode:2015A&A...575A..36M. doi:10.1051/0004-6361/201425331. 
  14. ^ Norton, Arthur P. (1973). Norton's Star Atlas. p. 118. ISBN 0-85248-900-5. 

Coordinates: Sky map 00h 45m 39.0777s, +74° 59′ 17.063″