Universe Guide


185 G. Oph - HD163641 - HIP87866

185 G. Oph is a blue giant star that can be located in the constellation of Ophiuchus. HIP87866 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD163641. The Id of the star in the Gould Star Catalogue is 185. Stars in the southern hemisphere are more likely to have a Gould Id than the northern hemisphere. For example, there are no Gould classified stars in Ursa Major.

Location of 185 G. Oph

The location of the star in the galaxy 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 185 G. Oph, the location is 17h 56m 55.96 and +06d29`15.8 .

Proper Motion of 185 G. Oph

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 -001.96 ± 000.27 towards the north and 018.70 ± 000.42 east if we saw them in the horizon.

Physical Properties (Colour, Temperature, Radius) of 185 G. Oph

185 G. Oph has a spectral type of B9III. This means the star is a blue giant star. The star has a B-V Colour Index of -0.01 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 9,679 Kelvin.

185 G. Oph has been calculated as 3.85 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 2,677,503.16.km.

185 G. Oph Apparent and Absolute Magnitudes

185 G. Oph has an apparent magnitude of 6.28 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 -0.32 If you used the 2007 Parallax value, you would get an absolute magnitude of -0.16. 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 185 G. Oph

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 4.79 which gave the calculated distance to 185 G. Oph as 680.93 light years away from Earth or 208.77 parsecs. It would take a spaceship travelling at the speed of light, 680.93 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 5.15 which put 185 G. Oph at a distance of 633.33 light years or 194.17 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.

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 Stellar Age, Metallicity or Mass is from the E.U. Exoplanets. The information was obtained as of 12th Feb 2017.

185 G. Oph Facts

Alternative Names

Traditional Name185 G. Oph
Hipparcos Library I.D.87866
Bonner DurchmusterungBD+06 3578
Gould I.D.185
Henry Draper Designation163641

Visual Facts

Star Typegiant star
Absolute Magnitude-0.32 / -0.16
Apparent Magnitude6.28
Right Ascension (R.A.)17h 56m 55.96
Declination (Dec.)+06d29`15.8
1997 Distance from Earth4.79 Parallax (milliarcseconds)
 680.93 Light Years
 208.77 Parsecs
2007 Revised Distance from Earth5.15 Parallax (milliarcseconds)
 633.33 Light Years
 194.17 Parsecs
Proper Motion Dec.-1.96 ± 0.27 milliarcseconds/year
Proper Motion RA.18.70 ± 0.42 milliarcseconds/year
B-V Index-0.01
Spectral TypeB9III
Colour(B) blue

Estimated Facts

Radius (x the Sun)3.85
Calculated Effective Temperature9,679 Kelvin

Sources and Links

SIMBAD SourceLink

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