Universe Guide


T Cassiopeiae, HD1845, HIP1834

T Cassiopeiae is a red pulsating 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.

HIP1834 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD1845.

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

Location of T 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 T Cassiopeiae, the location is 00h 23m 14.25 and +55d47`33.3 .

Proper Motion of T 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 -9.56 ± 0.78 miliarcseconds/year towards the north and 19.73 ± 1.09 miliarcseconds/year east if we saw them in the horizon.

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

T Cassiopeiae has a spectral type of M6-M9.0e. This means the star is a red star. The star has a B-V Colour Index of 1.2 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 4,568 Kelvin.

T Cassiopeiae Radius has been calculated as being 43.00 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 29,919,767.89.km. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 30.87. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures.

T Cassiopeiae Apparent and Absolute Magnitudes

T Cassiopeiae has an apparent magnitude of 8.85 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 -2.30 If you used the 2007 Parallax value, you would get an absolute magnitude of -1.58. 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 T Cassiopeiae

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 0.59 which gave the calculated distance to T Cassiopeiae as 5528.19 light years away from Earth or 1694.92 parsecs. It would take a spaceship travelling at the speed of light, 5528.19 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 0.82 which put T Cassiopeiae at a distance of 3977.60 light years or 1219.51 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 T Cassiopeiae

The star is a pulsating Omicron Ceti 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. T Cassiopeiae brightness ranges from a magnitude of 9.228 to a magnitude of 7.071 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 443.0 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.

T Cassiopeiae Facts

Alternative Names

Traditional/Proper NameT Cassiopeiae
Short NameT Cas
Hipparcos Library I.D.1834
Bonner DurchmusterungBD+54 48
Henry Draper Designation1845

Visual Facts

Star Type star
Absolute Magnitude-2.30 / -1.58
Visual / Apparent Magnitude8.85
Naked Eye VisibleRequires a 7x50 Binoculars - Magnitudes
Right Ascension (R.A.)00h 23m 14.25
Declination (Dec.)+55d47`33.3
Galactic Latitude-6.86 degrees
Galactic Longitude118.95 degrees
1997 Distance from Earth0.59 Parallax (milliarcseconds)
 5528.19 Light Years
 1694.92 Parsecs
2007 Revised Distance from Earth0.82 Parallax (milliarcseconds)
 3977.60 Light Years
 1219.51 Parsecs
Proper Motion Dec.-9.56 ± 0.78 milliarcseconds/year
Proper Motion RA.19.73 ± 1.09 milliarcseconds/year
B-V Index1.20
Radial Velocity-12.10 ± 3.20 km/s
Spectral TypeM6-M9.0e
Colour(M) Red

Variable Star Details

Variable Star ClassPulsating
Variable Star TypeOmicron Ceti
Mean Variability Period in Days443.000
Variable Magnitude Range (Brighter - Dimmer)7.071 - 9.228

Estimated Facts

Calculated Effective Temperature4,568 Kelvin

Sources and Links

SIMBAD SourceLink

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