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.[10]
The primary star in the YZ Cassiopeiae system is a white subgiant (main sequence) star of spectral type A1Vm and 2.31 solar masses[10] (M☉) with a less massive main sequence dwarf star of type F2V[2] and 1.35 M☉.[10] The apparent magnitude of the eclipsing binary varies from 5.65 to 6.05[2] with a period of 4.4672 days.[10] Combined, they appear to have a spectral type of A2IV.[10]
The binary has a dimmer (magnitude 9.7 according to Norton,[15] or 10.5 by SIMBAD) companion of 0.8 M☉[10] orbiting with a period of about 86 580 years.[10]
^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.
^ abcdefgEker, 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. S2CID118740259.