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Chi Cygni, HD187796, HIP97629, HR7564

Chi Cygni is a pulsating variable star that can be located in the constellation of Cygnus. The description is based on the spectral class. The star can not be seen by the naked eye, you need a telescope to see it.

Chi Cygni's Alternative Names

Chi Cygni (Chi Cyg) is the Bayer Classification for the star. The Id of the star in the Yale Bright Star Catalogue is HR7564. HIP97629 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD187796.

Chi Cygni has alternative name(s) :- , chi Cyg.

BD number is the number that the star was filed under in the Durchmusterung or Bonner Durchmusterung, a star catalogue that was put together by the Bonn Observatory between 1859 to 1903. The star's BD Number is BD+32 3593.

More details on star alternative names can be found at Star Names .

Location of Chi Cygni

The location of the star in the night sky 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 Chi Cygni, the location is 19h 50m 33.94 and +32° 54` 50.9 .

Proper Motion of Chi 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 -38.34 ± 0.91 miliarcseconds/year towards the north and -20.16 ± 1.10 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 1.60000 km/s with an error of about 0.60 km/s .

Physical Properties (Temperature) of Chi Cygni

Chi Cygni has a spectral type of S7,1e:. The star is 7,339.00 Parsecs from the Galactic Centre or terms of Light Years is 23,937.13 s. The star has a B-V Colour Index of 2.1 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 1,181 Kelvin.

Chi Cygni Radius has been calculated as being 62.00 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 43,138,073.12.km. If you need the diameter of the star, you just need to multiple the radius by 2. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 105.78. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures. The star's Iron Abundance is -1.00 with an error value of 9.99 Fe/H with the Sun has a value of 1 to put it into context.

Chi Cygni Apparent and Absolute Magnitudes

Chi Cygni has an apparent magnitude of 7.91 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 2.78 If you used the 2007 Parallax value, you would get an absolute magnitude of 1.62. 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 Chi Cygni

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 9.43 which gave the calculated distance to Chi Cygni as 345.88 light years away from Earth or 106.04 parsecs. It would take a spaceship travelling at the speed of light, 345.88 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 5.53 which put Chi Cygni at a distance of 589.81 light years or 180.83 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 7,339.00 Parsecs or 23,937.13 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 Chi Cygni

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. Chi Cygni brightness ranges from a magnitude of 10.334 to a magnitude of 4.827 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 402.3 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.

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Chi Cygni Facts

Visual Facts

Primary / Proper / Traditional NameChi Cygni
Alternative NamesChi Cyg, HD 187796, HIP 97629, HR 7564, BD+32 3593, chi Cyg
Spectral TypeS7,1e:
Multiple Star SystemYes
Star TypeVariable Star
GalaxyMilky Way
Absolute Magnitude2.78 / 1.62
Visual / Apparent Magnitude7.91
Naked Eye VisibleRequires a 7x50 Binoculars - Magnitudes
Right Ascension (R.A.)19h 50m 33.94
Declination (Dec.)+32° 54` 50.9
Galactic Latitude3.28 degrees
Galactic Longitude68.54 degrees
1997 Distance from Earth9.43 Parallax (milliarcseconds)
 345.88 Light Years
 106.04 Parsecs
2007 Distance from Earth5.53 Parallax (milliarcseconds)
 589.81 Light Years
 180.83 Parsecs
Galacto-Centric Distance23,937.13 Light Years / 7,339.00 Parsecs
Proper Motion Dec.-38.34 ± 0.91 milliarcseconds/year
Proper Motion RA.-20.16 ± 1.10 milliarcseconds/year
B-V Index2.10
Radial Velocity1.60 ± 0.60 km/s
Iron Abundance-1.00 ± 9.99 Fe/H
Semi-Major Axis7711.00

Companions (Multi-Star and Exoplanets) Facts

Exoplanet CountNone/Unaware

Variable Star Details

Variable Star ClassPulsating
Variable Star TypeOmicron Ceti
Mean Variability Period in Days402.300
Variable Magnitude Range (Brighter - Dimmer)4.827 - 10.334

Estimated Facts

Calculated Effective Temperature1,181 Kelvin

Sources and Links

SIMBAD SourceLink

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
187796+32 3593.0A-31.00000-38.00000M4Red

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