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9 Equulei, HD203291, HIP105413, HR8163

9 Equulei is a red giant star that can be located in the constellation of Equuleus. The description is based on the spectral class. The star can be seen with the naked eye, that is, you don't need a telescope/binoculars to see it.

9 Equulei's Alternative Names

The Id of the star in the Yale Bright Star Catalogue is HR8163. HIP105413 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD203291.

Flamsteed designations are named after the creator, Sir John Flamsteed. Sir John numbered the stars in the constellation with a number and the latin name, this star's Flamsteed designation is 9 Equulei with it shortened to 9 Equ.

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+06 4802.

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

Location of 9 Equulei

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 9 Equulei, the location is 21h 21m 04.80 and +07° 21` 16.4 .

Proper Motion of 9 Equulei

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 -17.11 ± 0.21 miliarcseconds/year towards the north and 42.98 ± 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 -22.35000 km/s with an error of about 0.25 km/s .

Physical Properties (Colour, Temperature) of 9 Equulei

9 Equulei has a spectral type of M2III. This means the star is a red giant star. The star is 7,313.00 Parsecs from the Galactic Centre or terms of Light Years is 23,852.33 s. The star has a B-V Colour Index of 1.66 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 3,608 Kelvin.

9 Equulei Radius has been calculated as being 53.50 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 37,228,192.69.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 32.99. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures.

9 Equulei Apparent and Absolute Magnitudes

9 Equulei has an apparent magnitude of 5.81 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 -1.75 If you used the 2007 Parallax value, you would get an absolute magnitude of -0.70. 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 9 Equulei

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 3.08 which gave the calculated distance to 9 Equulei as 1058.97 light years away from Earth or 324.68 parsecs. It would take a spaceship travelling at the speed of light, 1058.97 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 4.98 which put 9 Equulei at a distance of 654.95 light years or 200.80 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 7,313.00 Parsecs or 23,852.33 Light Years. The Galacto-Centric Distance is the distance from the star to the Centre of the Galaxy which is Sagittarius A*. 9 Equulei brightness ranges from a magnitude of 5.915 to a magnitude of 5.862 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 0.0 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.

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9 Equulei Facts

Visual Facts


Primary / Proper / Traditional Name9 Equulei
Alternative NamesHD 203291, HIP 105413, HR 8163, 9 Equ, BD+06 4802
Spectral TypeM2III
Multiple Star SystemNo / Unknown
Star TypeGiant Star
Colour red
GalaxyMilky Way
ConstellationEquuleus
Absolute Magnitude-1.75 / -0.70
Visual / Apparent Magnitude5.81
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)21h 21m 04.80
Declination (Dec.)+07° 21` 16.4
Galactic Latitude-28.55 degrees
Galactic Longitude59.19 degrees
1997 Distance from Earth3.08 Parallax (milliarcseconds)
 1058.97 Light Years
 324.68 Parsecs
2007 Distance from Earth4.98 Parallax (milliarcseconds)
 654.95 Light Years
 200.80 Parsecs
Galacto-Centric Distance23,852.33 Light Years / 7,313.00 Parsecs
Proper Motion Dec.-17.11 ± 0.21 milliarcseconds/year
Proper Motion RA.42.98 ± 0.41 milliarcseconds/year
B-V Index1.66
Radial Velocity-22.35 ± 0.25 km/s
Eccentricity0.16
Semi-Major Axis6420.00

Companions (Multi-Star and Exoplanets) Facts


Exoplanet CountNone/Unaware

Variable Star Details


Mean Variability Period in Days0.040
Variable Magnitude Range (Brighter - Dimmer)5.862 - 5.915

Estimated Facts


Calculated Effective Temperature3,608 Kelvin

Sources and Links


SIMBAD SourceLink

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