PZ Cassiopeiae

From Wikipedia, the free encyclopedia
Jump to: navigation, search
PZ Cassiopeiae
Observation data
Epoch J2000      Equinox J2000
Constellation Cassiopeia
Right ascension 23h 44m 03,28104s
Declination +61° 47′ 22,1823″
Apparent magnitude (V) 8.75
Spectral type M3Iab
B−V color index 2.5
Variable type SRc[1]
Radial velocity (Rv) -45.68 ± 0.68 km/s
Proper motion (μ) RA: -4.15 mas/yr
Dec.: -3.55 mas/yr
Radius 1,190–1,940 R
Other designations
V* PZ Cas, IRC +60417, HIP 117078, BD+60 2613, RAFGL 3138
Database references

PZ Cassiopeiae is a red supergiant star located in the Cassiopeia constellation, and a semi-regular variable star.


PZ Cas is an extreme luminous red supergiant star, one of the largest stars currently known with estimates at 1,190–1,940 times the Sun's radius.[2] Its distance from Earth was initially estimated to be around 7800 light-years (2.4 kiloparsecs). Subsequent studies of the star using the water masers that surround it have allowed to refine both the distance and the parameters of this star, deriving a distance of 9,160 light-years (2.81 kiloparsecs) that translates into a luminosity for it of between 240,000 and 270,000 times the Sun's luminosity, a radius 1,260-1,340 the solar one, and an initial mass 25 times that of our star. These parameters are all similar to those estimated for the red hypergiant VY Canis Majoris.[3]

PZ Cas is a slow semi-regular variable star with the period quoted as 925 days in the GCVS, although periods of 850 and 3,195 days have been derived.[1][4] The visual range is approximate magnitude 8-10, large for this type of variable.[4]


  1. ^ a b Bibcode1992A&A...254..133L
  2. ^ Levesque, E. M.; Massey, P.; Olsen, K. A. G.; Plez, B.; Josselin, E.; Maeder, A.; Meynet, G. (2005). "The Effective Temperature Scale of Galactic Red Supergiants: Cool, but Not as Cool as We Thought". The Astrophysical Journal 628 (2): 973. arXiv:astro-ph/0504337. Bibcode:2005ApJ...628..973L. doi:10.1086/430901.  edit
  3. ^ Kusuno, K.; Asaki, Y.; Imai, H.; Oyama, T. (2013). "Distance and Proper Motion Measurement of the Red Supergiant, Pz Cas, in Very Long Baseline Interferometry H2O Maser Astrometry". The Astrophysical Journal 774 (2): 107. doi:10.1088/0004-637X/774/2/107.  edit
  4. ^ a b Kiss, L. L.; Szabó, G. M.; Bedding, T. R. (2006). "Variability in red supergiant stars: Pulsations, long secondary periods and convection noise". Monthly Notices of the Royal Astronomical Society 372 (4): 1721. arXiv:astro-ph/0608438. Bibcode:2006MNRAS.372.1721K. doi:10.1111/j.1365-2966.2006.10973.x.  edit
<<< 8. RW Cephei 10. VV Cephei >>>