PZ Cassiopeiae
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Cassiopeia |
| Right ascension | 23h 44m 03.28104s[1] |
| Declination | +61° 47′ 22.1823″[1] |
| Apparent magnitude (V) | 8.90[2] |
| Characteristics | |
| Spectral type | M3I[3] |
| U−B color index | +1.32[2] |
| B−V color index | +2.58[2] |
| Variable type | SRc[4] |
| Astrometry | |
| Radial velocity (Rv) | -45.68 ± 0.68[5] km/s |
| Proper motion (μ) | RA: −4.15[1] mas/yr Dec.: −3.55[1] mas/yr |
| Parallax (π) | 0.18 ± 0.85[1] mas |
| Distance | 2,810[6] pc |
| Absolute magnitude (MV) | −7.89[3] |
| Details | |
| Radius | 1,190(-1,940)[3] R☉ |
| Luminosity | 240,000-270,000[6] L☉ |
| Surface gravity (log g) | −0.5[3] cgs |
| Temperature | 3,600[3] K |
| Other designations | |
| Database references | |
| SIMBAD | data |
PZ Cassiopeiae is a red supergiant star located in the Cassiopeia constellation, and a semi-regular variable star.
Characteristics
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. 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.[6]
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.[4][7] The visual range is approximate magnitude 8-10, large for this type of variable.[7]
References
- 1 2 3 4 5 Van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics 474 (2): 653. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357.
- 1 2 3 Ducati, J. R. (2002). "VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system". CDS/ADC Collection of Electronic Catalogues 2237. Bibcode:2002yCat.2237....0D.
- 1 2 3 4 5 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.
- 1 2 Le Squeren, A. M.; Sivagnanam, P.; Dennefeld, M.; David, P. (1992). "A Complete Survey of OH / Infrared Objects from the IRAS LRS Sources Within a Domain of the Color Diagram". Astronomy and Astrophysics 254: 133. Bibcode:1992A&A...254..133L.
- ↑ Famaey, B.; Jorissen, A.; Luri, X.; Mayor, M.; Udry, S.; Dejonghe, H.; Turon, C. (2005). "Local kinematics of K and M giants from CORAVEL/Hipparcos/Tycho-2 data. Revisiting the concept of superclusters". Astronomy and Astrophysics 430: 165. Bibcode:2005A&A...430..165F. doi:10.1051/0004-6361:20041272.
- 1 2 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. arXiv:1308.3580. Bibcode:2013ApJ...774..107K. doi:10.1088/0004-637X/774/2/107.
- 1 2 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.
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