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HD 125809

HD 125809 Facts

HD 125809's Alternative Names

HIP70320 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD125809.

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

Location of HD 125809

The location of the supergiant 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 object is compared to the celestial equator and is expressed in degrees. For HD 125809, the location is 14h 23m 15.36 and -47° 25` 01.0 .

Radial Velocity and Proper Motion of HD 125809

Proper Motion

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 -5.25 ± 0.31 miliarcseconds/year towards the north and -6.06 ± 0.49 miliarcseconds/year east if we saw them in the horizon.

Radial Velocity

The Radial Velocity, that is the speed at which the star is moving away/towards the Sun is -14.00 km/s with an error of about 999.00 km/s . When the value is negative then the star and the Sun are getting closer to one another, likewise, a positive number means that two stars are moving away. Its nothing to fear as the stars are so far apart, they won't collide in our life-time, if ever.

Physical Properties (Colour, Temperature) of HD 125809

HD 125809 Colour and Temperature

HD 125809 has a spectral type of G5Ib. This means the star is a white to yellow supergiant star. The star has a B-V Colour Index of 1.25 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 4,476 Kelvin.

HD 125809 Radius

Radius has been calculated as being 80.38 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 55,929,730.04.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 38.83. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures.

HD 125809 Apparent and Absolute Magnitudes

HD 125809 has an apparent magnitude of 6.41 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 -3.57 If you used the 2007 Parallax value, you would get an absolute magnitude of -1.99. 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 HD 125809

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 1.01 which gave the calculated distance to HD 125809 as 3229.34 light years away from Earth or 990.10 parsecs. It would take a spaceship travelling at the speed of light, 3229.34 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 2.09 which put HD 125809 at a distance of 1560.59 light years or 478.47 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.

Using the 2007 distance, the star is roughly 98,690,834.16 Astronomical Units from the Earth/Sun give or take a few. An Astronomical Unit is the distance between Earth and the Sun. The number of A.U. is the number of times that the star is from the Earth compared to the Sun.

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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Additional HD 125809 Facts and Figures

Visual Facts


Primary / Proper / Traditional NameHD 125809
Alternative NamesHD 125809, HIP 70320
Spectral TypeG5Ib
Constellation's Main StarNo
Multiple Star SystemNo / Unknown
Star Type very luminous Supergiant Star
ColourWhite to Yellow
GalaxyMilky Way
ConstellationLupus
Absolute Magnitude -3.57 / -1.99
Visual / Apparent Magnitude6.41
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)14h 23m 15.36
Declination (Dec.)-47° 25` 01.0
Galactic Latitude12.64 degrees
Galactic Longitude318.62 degrees
1997 Distance from Earth1.01 Parallax (milliarcseconds)
 3229.34 Light Years
 990.10 Parsecs
2007 Distance from Earth2.09 Parallax (milliarcseconds)
 1560.59 Light Years
 478.47 Parsecs
 98,690,834.16 Astronomical Units
Proper Motion Dec.-5.25 ± 0.31 milliarcseconds/year
Proper Motion RA.-6.06 ± 0.49 milliarcseconds/year
B-V Index1.25
Radial Velocity-14.00 ± 999.00 km/s

Companions (Multi-Star and Exoplanets) Facts


Exoplanet CountNone/Unaware

Estimated Calculated Facts


Radius (x the Sun)38.83
Effective Temperature4,476 Kelvin

Sources and Links


SIMBAD SourceLink

Related Stars


Comments and Questions

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