Universe Guide


69 Cygni, HD204172, HIP105811

69 Cygni is a blue very luminous supergiant star that can be located in the constellation of Cygnus. The star can be seen with the naked eye, that is, you don't need a telescope/binoculars to see it.

HIP105811 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD204172.

69 Cygni has alternative name(s), V2157 Cyg.

Location of 69 Cygni

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 69 Cygni, the location is 21h 25m 47.02 and +36d40`02.7 .

Proper Motion of 69 Cygni

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 -9.65 ± 0.24 miliarcseconds/year towards the north and 7.49 ± 0.39 miliarcseconds/year east if we saw them in the horizon.

69 Cygni 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 320000.0000000 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 69 Cygni

69 Cygni has a spectral type of B0Ib. This means the star is a blue supergiant star. The star has a B-V Colour Index of 0.03 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 9,610 Kelvin.

69 Cygni Radius has been calculated as being 18.60 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 12,941,287.28.km. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 61.03. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures.

69 Cygni Apparent and Absolute Magnitudes

69 Cygni has an apparent magnitude of 5.93 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 -3.71 If you used the 2007 Parallax value, you would get an absolute magnitude of -6.29. 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 69 Cygni

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 1.18 which gave the calculated distance to 69 Cygni as 2764.10 light years away from Earth or 847.46 parsecs. It would take a spaceship travelling at the speed of light, 2764.10 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 0.36 which put 69 Cygni at a distance of 9060.09 light years or 2777.78 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. 69 Cygni brightness ranges from a magnitude of 5.918 to a magnitude of 5.867 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 0.1 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.

69 Cygni Facts

Alternative Names

Traditional/Proper Name69 Cygni
Flamsteed Name69 Cygni
Flamsteed Short Name69 Cyg
Short NameV2157 Cyg
Hipparcos Library I.D.105811
Bonner DurchmusterungBD+36 4557
Henry Draper Designation204172

Visual Facts

Star Typesupergiant star
Absolute Magnitude-3.71 / -6.29
Visual / Apparent Magnitude5.93
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)21h 25m 47.02
Declination (Dec.)+36d40`02.7
Galactic Latitude-9.96 degrees
Galactic Longitude83.39 degrees
1997 Distance from Earth1.18 Parallax (milliarcseconds)
 2764.10 Light Years
 847.46 Parsecs
2007 Revised Distance from Earth0.36 Parallax (milliarcseconds)
 9060.09 Light Years
 2777.78 Parsecs
Proper Motion Dec.-9.65 ± 0.24 milliarcseconds/year
Proper Motion RA.7.49 ± 0.39 milliarcseconds/year
B-V Index0.03
Radial Velocity2.80 ± 2.90 km/s
Spectral TypeB0Ib
Colour(B) blue

Variable Star Details

Mean Variability Period in Days0.057
Variable Magnitude Range (Brighter - Dimmer)5.867 - 5.918

Estimated Facts

Luminosity (x the Sun)320,000.0000000
Calculated Effective Temperature9,610 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
204172+36 4557.0A5.800004.00000-4.00000B0Blue/White

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