Universe Guide


PZ Cassiopeiae, HIP117078

PZ Cassiopeiae is a red pulsating very luminous supergiant star that can be located in the constellation of Cassiopeia. The star can not be seen by the naked eye, you need a telescope to see it.

HIP117078 is the reference name for the star in the Hipparcos Star Catalogue.

PZ Cassiopeiae has alternative name(s), PZ Cas.

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

Location of PZ Cassiopeiae

The location of the star in the galaxy 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 +61d47`22.2 .

Proper Motion of PZ Cassiopeiae

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.

PZ Cassiopeiae Luminosity

Luminosity is the amount of energy that a star pumps out and its relative to the amount that our star, the Sun gives out. The figure of 54000.0000000 that I have given is based on the Spectral Types page that I have found on the Internet. You might find a different figure, one that may have been calculated rather than generalised that I have done. The figure is always the amount times the luminosity of the Sun. It is an imprecise figure because of a number of factors including but not limited to whether the star is a variable star and distance.

Physical Properties (Colour, Temperature, Radius) of PZ Cassiopeiae

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. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures.

PZ Cassiopeiae Apparent and Absolute Magnitudes

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.

Distance to PZ Cassiopeiae

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.

Variable Type of PZ Cassiopeiae

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).

Source of Information

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.

PZ Cassiopeiae Facts

Alternative Names

Traditional/Proper NamePZ Cassiopeiae
Short NamePZ Cas
Hipparcos Library I.D.117078
Bonner DurchmusterungBD+60 2613

Visual Facts

Star Typesupergiant star
Visual / Apparent Magnitude8.22
Naked Eye VisibleRequires a 7x50 Binoculars - Magnitudes
Right Ascension (R.A.)23h 44m 03.29
Declination (Dec.)+61d47`22.2
Galactic Latitude-0.05 degrees
Galactic Longitude115.06 degrees
1997 Distance from Earth-0.18 Parallax (milliarcseconds)
 -18120.19 Light Years
 -5555.56 Parsecs
2007 Revised Distance from Earth0.18 Parallax (milliarcseconds)
 18120.19 Light Years
 5555.56 Parsecs
Proper Motion Dec.-3.55 ± 0.61 milliarcseconds/year
Proper Motion RA.-4.15 ± 0.85 milliarcseconds/year
B-V Index2.60
Radial Velocity-45.68 ± 0.68 km/s
Spectral TypeM3Ia
Colour(M) Red

Variable Star Details

Variable Star ClassPulsating
Variable Star TypeSlow Irregular
Mean Variability Period in Days0.520
Variable Magnitude Range (Brighter - Dimmer)8.031 - 8.641

Estimated Facts

Luminosity (x the Sun)54,000.0000000
Calculated Effective Temperature2 Kelvin

Sources and Links

SIMBAD SourceLink

Related Stars

Multi-Star System

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. IdB.D. IdStar CodeMagnitudeR.A.Dec.SpectrumColourYear
+60 2613.0A8.90000

Location of PZ Cassiopeiae in Cassiopeia

PZ Cassiopeiae Location in Cassiopeia

The map was generated using Night Vision, an awesome free application by Brian Simpson.

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