Universe Guide

12 Ophiuchi - HD149661 - HIP81300

12 Ophiuchi is an orange to red main sequence dwarf star that can be located in the constellation of Ophiuchus. HIP81300 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD149661. The Id of the star in the Gould Star Catalogue is 27. 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. 12 Ophiuchi has alternative name(s), 12 Ophiuchi , 12 Oph.

Location of 12 Ophiuchi

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 12 Ophiuchi, the location is 16h 36m 21.18 and -02 d 19 ` 25.8 .

Proper Motion of 12 Ophiuchi

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 -310.00 ± 000.00 towards the north and 456.00 ± 000.00 east if we saw them in the horizon.

Physical Properties (Colour, Temperature, Radius) of 12 Ophiuchi

12 Ophiuchi has a spectral type of K2V. This means the star is an orange to red coloured main sequence dwarf star. The star has a B-V Colour Index of 0.82 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 5,236 Kelvin.

12 Ophiuchi has been calculated as 0.78 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 543,665.17.km.

12 Ophiuchi Apparent and Absolute Magnitudes

12 Ophiuchi has an apparent magnitude of 5.77 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 5.81 If you used the 2007 Parallax value, you would get an absolute magnitude of 5.83. 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 12 Ophiuchi

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 102.00 which gave the calculated distance to 12 Ophiuchi as 31.98 light years away from Earth or 9.80 parsecs. In 2007, Hipparcos data was revised with a new parallax of 103.00 which put 12 Ophiuchi at a distance of 31.67 light years or 9.71 parsecs.

It would take a spaceship travelling at the speed of light, 31.98 years using the 1997 distance to get there. We don't have the technology or spaceship that can carry people over that distance yet.

12 Ophiuchi Facts

Traditional Name12 Ophiuchi
Short Name12 Oph
Alternative Name(s)12 Ophiuchi
Hipparcos Library I.D.81300
Bonner DurchmusterungBD-01 3220
Gould I.D.27
Henry Draper Designation149661
Celestial TypeStar
Absolute Magnitude5.81 / 5.83
Apparent Magnitude5.77
Right Ascension (R.A.)16h 36m 21.18
Declination (Dec.)-02 d 19 ` 25.8
1997 Distance from Earth102.00 Parallax (milliarcseconds)
 31.98 Light Years
 9.80 Parsecs
2007 Distance from Earth103.00 Parallax (milliarcseconds)
 31.67 Light Years
 9.71 Parsecs
Proper Motion Dec.-310.00 ± 0.00 milliarcseconds/year
Proper Motion RA.456.00 ± 0.00 milliarcseconds/year
B-V Index0.82
Spectral TypeK2V
Colour(K) Orange to Red
Star Typemain sequence dwarf star
Radius (x the Sun)0.78
Calculated Effective Temperature5,236 Kelvin

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