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Gliese 251

Gliese 251 Facts

Gliese 251's Alternative Names

HIP33226 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD265866. The Gliese ID of the star is GL 251. The star was part of the original catalogue devised by German Astronomer Wilheim Gliese of stars located within 20 parsecs of Earth. Star Names

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

Location of Gliese 251

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 object is compared to the celestial equator and is expressed in degrees. For Gliese 251, the location is 06h 54m 49.47 and +33° 16` 08.9 .

Radial Velocity and Proper Motion of Gliese 251

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 -398.40 ± 0.77 milliarcseconds/year towards the north and -723.99 ± 1.60 milliarcseconds/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 22.91 km/s with an error of about 0.10 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.

Gliese 251 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 0.01 that I have given is based on the value in the Simbad Hipparcos Extended Catalogue at the University of Strasbourg from 2012.

Physical Properties (Colour, Temperature) of Gliese 251

Gliese 251 Colour and Temperature

Gliese 251 has a spectral type of K:.... This means the star is a orange to red star. The star has a B-V Colour Index of 1.58 which means the star's temperature is about 3,828 Kelvin. The temperature was calculated using information from Morgans @ Uni.edu at being .

Gliese 251 Radius

Radius has been calculated as being 0.12 times bigger than the Sun. The Sun's radius is 695,800km, therefore the star's radius is an estimated 85,769.76.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 0.12. 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 -1.08 with an error value of 0.04 Fe/H with the Sun has a value of 1 to put it into context.

Gliese 251 Apparent and Absolute Magnitudes

Gliese 251 has an apparent magnitude of 9.89 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 11.18 If you used the 2007 Parallax value, you would get an absolute magnitude of 11.15. 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 Gliese 251

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 181.32 which gave the calculated distance to Gliese 251 as 17.99 light years away from Earth or 5.52 parsecs. If you want that in miles, it is 12,064,393,156.

In 2007, Hipparcos data was revised with a new parallax of 179.01 which put Gliese 251 at a distance of 18.22 light years or 5.59 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 1,153,012.23 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.

The star's Galacto-Centric Distance is 7,405.00 Parsecs or 24,152.40 Light Years. The Galacto-Centric Distance is the distance from the star to the Centre of the Galaxy which is Sagittarius A*.

Travel Time to Gliese 251

The time it will take to travel to this star is dependent on how fast you are going. U.G. has done some calculations as to how long it will take going at differing speeds. A note about the calculations, when I'm talking about years, I'm talking non-leap years only (365 days).

The New Horizons space probe is the fastest probe that we've sent into space at the time of writing. Its primary mission was to visit Pluto which at the time of launch (2006), Pluto was still a planet.

DescriptionSpeed (m.p.h.)Time (years)
Walking43,054,658,745.10
Car120101,821,958.17
Airbus A38073616,601,406.22
Speed of Sound (Mach 1)767.26915,924,838.59
Concorde (Mach 2)1,534.547,962,408.92
New Horizons Probe33,000370,261.67
Speed of Light670,616,629.0018.22

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 Gliese 251 Facts and Figures

Visual Facts


Primary / Proper / Traditional NameGliese 251
Alternative NamesHD 265866, HIP 33226, Gliese 251
Spectral TypeK:...
Constellation's Main StarNo
Multiple Star SystemNo / Unknown
Star TypeStar
ColourOrange to Red
GalaxyMilky Way
ConstellationGemini
Absolute Magnitude 11.18 / 11.15
Visual / Apparent Magnitude9.89
Naked Eye VisibleRequires a 7x50 Binoculars - Magnitudes
Right Ascension (R.A.)06h 54m 49.47
Declination (Dec.)+33° 16` 08.9
Galactic Latitude15.14 degrees
Galactic Longitude182.94 degrees
1997 Distance from Earth181.32 Parallax (milliarcseconds)
 17.99 Light Years
 5.52 Parsecs
2007 Distance from Earth179.01 Parallax (milliarcseconds)
 18.22 Light Years
 5.59 Parsecs
 1,153,012.23 Astronomical Units
Galacto-Centric Distance24,152.40 Light Years / 7,405.00 Parsecs
Proper Motion Dec.-398.40 ± 0.77 milliarcseconds/year
Proper Motion RA.-723.99 ± 1.60 milliarcseconds/year
B-V Index1.58
Radial Velocity22.91 ± 0.10 km/s
Iron Abundance-1.08 ± 0.04 Fe/H
Eccentricity0.13
Semi-Major Axis8275.00
Stellar Luminosity (Lsun)0.01

Companions (Multi-Star and Exoplanets) Facts


Exoplanet CountNone/Unaware

Estimated Calculated Facts


Radius (x the Sun)0.12
Effective Temperature3,828 Kelvin

Sources and Links


SIMBAD SourceLink

Related Stars


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