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Omicron1 Cygni, 31 Cygni, HD192577, HIP99675, HR7735

Omicron1 Cygni is a orange to red eclipsing binary system luminous giant star that can be located in the constellation of Cygnus. Omicron1 Cygni is the brightest star in Cygnus based on the Hipparcos 2007 apparent magnitude. The star can be seen with the naked eye, that is, you don't need a telescope/binoculars to see it.

Omicron1 Cygni is the Bayer Classification for the star. The Id of the star in the Yale Bright Star Catalogue is HR7735. HIP99675 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD192577.

Omicron1 Cygni has alternative name(s), V695 Cyg.

Location of Omicron1 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 Omicron1 Cygni, the location is 20h 13m 37.90 and +46d 44` 28.8 .

Proper Motion of Omicron1 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 1.21 ± 0.33 miliarcseconds/year towards the north and 4.78 ± 0.41 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 -7.24000 km/s with an error of about 0.30 km/s .

Physical Properties (Colour, Temperature, Radius) of Omicron1 Cygni

Omicron1 Cygni has a spectral type of K2II+.... This means the star is a orange to red luminous giant star. The star is 7371.00000000 Parsecs from the Galactic Centre or terms of Light Years is 24041.5000862400000000s. The star has a B-V Colour Index of 1.27 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 4,440 Kelvin.

Omicron1 Cygni Radius has been calculated as being 113.81 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 79,188,844.74.km. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 74.16. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures.

Omicron1 Cygni Apparent and Absolute Magnitudes

Omicron1 Cygni has an apparent magnitude of 3.80 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 -4.29 If you used the 2007 Parallax value, you would get an absolute magnitude of -3.36. 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 Omicron1 Cygni

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 2.41 which gave the calculated distance to Omicron1 Cygni as 1353.37 light years away from Earth or 414.94 parsecs. It would take a spaceship travelling at the speed of light, 1353.37 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 3.69 which put Omicron1 Cygni at a distance of 883.91 light years or 271.00 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's Galacto-Centric Distance is 7,371.00 Parsecs or 24,041.50 Light Years. The Galacto-Centric Distance is the distance from the star to the Centre of the Galaxy which is Sagittarius A*.

Variable Type of Omicron1 Cygni

The star is a eclipsing binary system Beta Persei (Algol) 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. Omicron1 Cygni brightness ranges from a magnitude of 4.030 to a magnitude of 3.890 over its variable period. The smaller the magnitude, the brighter the star.

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.

Omicron1 Cygni Facts

Alternative Names

Flamsteed Name31 Cygni
Flamsteed Short Name31 Cyg
Short NameV695 Cyg
Bayer DesignationOmicron1 Cygni
Hipparcos Library I.D.99675
Yale Bright Star Catalogue (HR) Id7735
Bonner DurchmusterungBD+46 2882
Henry Draper Designation192577

Visual Facts

Star Typeluminous giant star
Absolute Magnitude-4.29 / -3.36
Visual / Apparent Magnitude3.80
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)20h 13m 37.90
Declination (Dec.)+46d 44` 28.8
Galactic Latitude6.78 degrees
Galactic Longitude82.68 degrees
1997 Distance from Earth2.41 Parallax (milliarcseconds)
 1353.37 Light Years
 414.94 Parsecs
2007 Revised Distance from Earth3.69 Parallax (milliarcseconds)
 883.91 Light Years
 271.00 Parsecs
Galacto-Centric Distance24,041.50 Light Years / 7,371.00 Parsecs
Proper Motion Dec.1.21 ± 0.33 milliarcseconds/year
Proper Motion RA.4.78 ± 0.41 milliarcseconds/year
B-V Index1.27
Radial Velocity-7.24 ± 0.30 km/s
Semi-Major Axis16.17
Orbital Period (Days)3784.30
Argument Of Periastron201.10
Spectral TypeK2II+...
Associated / Clustered StarsOmicron2 Cygni
Colour(K) Orange to Red

Variable Star Details

Variable Star ClassEclipsing binary system
Variable Star TypeBeta Persei (Algol)
Variable Magnitude Range (Brighter - Dimmer)3.890 - 4.030

Estimated Facts

Calculated Effective Temperature4,440 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
192577+46 2882.0A4.000000.000005.00000K0Orange

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