PZ Cassiopeiae is a red pulsating supergiant star that can be located in the constellation of Cassiopeia. The description is based on the spectral class. The star can not be seen by the naked eye, you need a telescope to see it.
PZ Cassiopeia is one of the largest stars to have been so far discovered. It is estimated at being 1,260 to 1,340 the size of the Sun. It is not the largest, that accolade belongs to UY Scuti. The star is believed to have a companion star orbiting alongside it. Although below it says the variability is 925 days, other lengths have been derived. ref:Wiki
HIP117078 is the reference name for the star in the Hipparcos Star Catalogue.
PZ Cassiopeiae has alternative name(s) :- , PZ Cas.
BD number is the number that the star was filed under in the Durchmusterung or Bonner Durchmusterung, a star catalogue that was put together by the Bonn Observatory between 1859 to 1903. The star's BD Number is BD+60 2613.
More details on star alternative names can be found at Star Names .
The location of the star in the night sky is determined by the Right Ascension (R.A.) and Declination (Dec.), these are equivalent to the Longitude and Latitude on the Earth. The Right Ascension is how far expressed in time (hh:mm:ss) the star is along the celestial equator. If the R.A. is positive then its eastwards. The Declination is how far north or south the star is compared to the celestial equator and is expressed in degrees. For PZ Cassiopeiae, the location is 23h 44m 03.29 and +61° 47` 22.2 .
All stars like planets orbit round a central spot, in the case of planets, its the central star such as the Sun. In the case of a star, its the galactic centre. The constellations that we see today will be different than they were 50,000 years ago or 50,000 years from now. Proper Motion details the movements of these stars and are measured in milliarcseconds. The star is moving -3.55 ± 0.61 miliarcseconds/year towards the north and -4.15 ± 0.85 miliarcseconds/year east if we saw them in the horizon. The Radial Velocity, that is the speed at which the star is moving away/towards us is -45.68000 km/s with an error of about 0.68 km/s .
PZ Cassiopeiae has a spectral type of M3Ia. This means the star is a red supergiant star. The star has a B-V Colour Index of 2.6 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 2 Kelvin.
PZ Cassiopeiae has an apparent magnitude of 8.22 which is how bright we see the star from Earth. Apparent Magnitude is also known as Visual Magnitude. If you used the 1997 Parallax value, you would get an absolute magnitude of If you used the 2007 Parallax value, you would get an absolute magnitude of -5.50. Magnitude, whether it be apparent/visual or absolute magnitude is measured by a number, the smaller the number, the brighter the Star is. Our own Sun is the brightest star and therefore has the lowest of all magnitudes, -26.74. A faint star will have a high number.
Using the original Hipparcos data that was released in 1997, the parallax to the star was given as -0.18 which gave the calculated distance to PZ Cassiopeiae as -18120.19 light years away from Earth or -5555.56 parsecs. It would take a spaceship travelling at the speed of light, -18120.19 years to get there. We don't have the technology or spaceship that can carry people over that distance yet.
In 2007, Hipparcos data was revised with a new parallax of 0.18 which put PZ Cassiopeiae at a distance of 18120.19 light years or 5555.56 parsecs. It should not be taken as though the star is moving closer or further away from us. It is purely that the distance was recalculated.
The star is a pulsating Slow Irregular variable type which means that its size changes over time. The Variable Type is usually named after the first star of that type to be spotted. PZ Cassiopeiae brightness ranges from a magnitude of 8.641 to a magnitude of 8.031 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 0.5 days (variability).
The source of the information if it has a Hip I.D. is from Simbad, the Hipparcos data library based at the University at Strasbourg, France. Hipparcos was a E.S.A. satellite operation launched in 1989 for four years. The items in red are values that I've calculated so they could well be wrong. Information regarding Metallicity and/or Mass is from the E.U. Exoplanets. The information was obtained as of 12th Feb 2017.
|Primary / Proper / Traditional Name||PZ Cassiopeiae|
|Alternative Names||HIP 117078, BD+60 2613, PZ Cas|
|Multiple Star System||Yes|
|Star Type||very luminous Supergiant Star|
|Visual / Apparent Magnitude||8.22|
|Naked Eye Visible||Requires a 7x50 Binoculars - Magnitudes|
|Right Ascension (R.A.)||23h 44m 03.29|
|Declination (Dec.)||+61° 47` 22.2|
|Galactic Latitude||-0.05 degrees|
|Galactic Longitude||115.06 degrees|
|1997 Distance from Earth||-0.18 Parallax (milliarcseconds)|
|-18120.19 Light Years|
|2007 Distance from Earth||0.18 Parallax (milliarcseconds)|
|18120.19 Light Years|
|Proper Motion Dec.||-3.55 ± 0.61 milliarcseconds/year|
|Proper Motion RA.||-4.15 ± 0.85 milliarcseconds/year|
|Radial Velocity||-45.68 ± 0.68 km/s|
|Variable Star Class||Pulsating|
|Variable Star Type||Slow Irregular|
|Mean Variability Period in Days||0.520|
|Variable Magnitude Range (Brighter - Dimmer)||8.031 - 8.641|
|Calculated Effective Temperature||2 Kelvin|
The star has been identified as being a multi-star system, one in which there is at least one star in close orbit to another star or two or more stars orbiting a central point. The stars may be of equal mass, unequal mass where one star is stronger than the other or be in groups orbiting a central point which doesn't necessarily have to be a star. More information can be found on my dedicated multiple star systems page. The source of the info is Simbad. The file is dated 2000 so any differences between this and any other source will be down to the actual source from where the information came from.
|Proper Motion mas/yr|
|H.D. Id||B.D. Id||Star Code||Magnitude||R.A.||Dec.||Spectrum||Colour||Year|