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259 G. Sagittarii, HD189198, HIP98512

259 G. Sagittarii is a blue giant star that can be located in the constellation of Sagittarius. 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.

259 G. Sagittarii's Alternative Names

HIP98512 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD189198.

259 G. Sagittarii has alternative name(s) :- 259 G. Sgr.

The Gould star designation is one that was designed by American astronomer, Benjamin Apthorp Gould. Gould stars are predominantly in the Southern and Equatorial constellations but do appear in northern constellations such as Bootes and Orion. The star has the designation 259 G. Sagittarii. There are no stars with a Gould designation in Ursa Major for example.

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

Location of 259 G. Sagittarii

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 259 G. Sagittarii, the location is 20h 00m 48.32 and -45° 06` 46.6 .

Proper Motion of 259 G. Sagittarii

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 4.42 ± 0.36 miliarcseconds/year towards the north and 1.94 ± 0.81 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 3.00000 km/s with an error of about 4.30 km/s .

259 G. Sagittarii 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 25.96 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 259 G. Sagittarii

259 G. Sagittarii has a spectral type of A8III. This means the star is a blue giant star. The star is 7,331.00 Parsecs from the Galactic Centre or terms of Light Years is 23,911.03 s. The star has a B-V Colour Index of 0.29 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 7,270 Kelvin.

259 G. Sagittarii Radius has been calculated as being 4.49 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 3,121,139.76.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 3.31. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures.

259 G. Sagittarii Apparent and Absolute Magnitudes

259 G. Sagittarii has an apparent magnitude of 5.80 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 0.59 If you used the 2007 Parallax value, you would get an absolute magnitude of 1.25. 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 259 G. Sagittarii

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 9.07 which gave the calculated distance to 259 G. Sagittarii as 359.61 light years away from Earth or 110.25 parsecs. It would take a spaceship travelling at the speed of light, 359.61 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 12.29 which put 259 G. Sagittarii at a distance of 265.39 light years or 81.37 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 7,331.00 Parsecs or 23,911.03 Light Years. The Galacto-Centric Distance is the distance from the star to the Centre of the Galaxy which is Sagittarius A*.

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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259 G. Sagittarii Facts

Visual Facts


Primary / Proper / Traditional Name259 G. Sagittarii
Alternative Names259 G. Sgr, HD 189198, HIP 98512
Spectral TypeA8III
Multiple Star SystemNo / Unknown
Star TypeGiant Star
Colour blue
GalaxyMilky Way
ConstellationSagittarius
Absolute Magnitude0.59 / 1.25
Visual / Apparent Magnitude5.80
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)20h 00m 48.32
Declination (Dec.)-45° 06` 46.6
Galactic Latitude-30.68 degrees
Galactic Longitude354.49 degrees
1997 Distance from Earth9.07 Parallax (milliarcseconds)
 359.61 Light Years
 110.25 Parsecs
2007 Distance from Earth12.29 Parallax (milliarcseconds)
 265.39 Light Years
 81.37 Parsecs
Galacto-Centric Distance23,911.03 Light Years / 7,331.00 Parsecs
Proper Motion Dec.4.42 ± 0.36 milliarcseconds/year
Proper Motion RA.1.94 ± 0.81 milliarcseconds/year
B-V Index0.29
Radial Velocity3.00 ± 4.30 km/s
Eccentricity0.17
Semi-Major Axis8555.00
Stellar Luminosity (Lsun)25.96

Companions (Multi-Star and Exoplanets) Facts


Exoplanet CountNone/Unaware

Estimated Facts


Calculated Effective Temperature7,270 Kelvin

Sources and Links


SIMBAD SourceLink

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