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39 Ceti - HD7672 - HIP5951

39 Ceti is a white to yellow eclipsing binary system subgiant star that can be located in the constellation of Cetus. HIP5951 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD7672. The Id of the star in the Gould Star Catalogue is 121. Stars in the southern hemisphere are more likely to have a Gould Id than the northern hemisphere. For example, there are no Gould classified stars in Ursa Major. 39 Ceti has alternative name(s), 39 Ceti , AY_Cet, 39 Cet.

Location of 39 Ceti

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 39 Ceti, the location is 01h 16m 36.35 and -02d30`00.8 .

Proper Motion of 39 Ceti

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 -063.55 ± 000.17 towards the north and -099.43 ± 000.27 east if we saw them in the horizon.

Physical Properties (Colour, Temperature, Radius) of 39 Ceti

39 Ceti has a spectral type of G5III-IVe. This means the star is a white to yellow subgiant star. The star has a B-V Colour Index of 0.88 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 5,096 Kelvin.

39 Ceti has been calculated as 7.73 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 5,381,702.23.km.

39 Ceti Apparent and Absolute Magnitudes

39 Ceti has an apparent magnitude of 5.42 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 0.95 If you used the 2007 Parallax value, you would get an absolute magnitude of 0.89. 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 39 Ceti

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 12.74 which gave the calculated distance to 39 Ceti as 256.02 light years away from Earth or 78.49 parsecs. It would take a spaceship travelling at the speed of light, 256.02 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 12.41 which put 39 Ceti at a distance of 262.82 light years or 80.58 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 39 Ceti

The star is a eclipsing binary system RS Canum Venaticorum 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. 39 Ceti brightness ranges from a magnitude of 6.000 to a magnitude of 6.000 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 77.0 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 Stellar Age, Metallicity or Mass is from the E.U. Exoplanets. The information was obtained as of 12th Feb 2017.

39 Ceti Facts

Alternative Names

Traditional Name39 Ceti
Short NameAY Cet, 39 Cet
Alternative Name(s)39 Ceti
Hipparcos Library I.D.5951
Bonner DurchmusterungBD-03 172
Gould I.D.121
Henry Draper Designation7672

Visual Facts

Star Typesubgiant star
Absolute Magnitude0.95 / 0.89
Apparent Magnitude5.42
Right Ascension (R.A.)01h 16m 36.35
Declination (Dec.)-02d30`00.8
1997 Distance from Earth12.74 Parallax (milliarcseconds)
 256.02 Light Years
 78.49 Parsecs
2007 Revised Distance from Earth12.41 Parallax (milliarcseconds)
 262.82 Light Years
 80.58 Parsecs
Proper Motion Dec.-63.55 ± 0.17 milliarcseconds/year
Proper Motion RA.-99.43 ± 0.27 milliarcseconds/year
B-V Index0.88
Spectral TypeG5III-IVe
Colour(G) White to Yellow

Variable Star Details

Variable Star ClassEclipsing binary system
Variable Star TypeRS Canum Venaticorum
Mean Variability Period in Days77.000

Estimated Facts

Radius (x the Sun)7.73
Calculated Effective Temperature5,096 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
7672-03 172.0A5.50000-108.00000-59.00000G0Yellow
B11.200001913

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