Universe Guide


61 Ophiuchi, HD161270, HIP86831

61 Ophiuchi is a blue subgiant star that can be located in the constellation of Ophiuchus. The star can be seen with the naked eye, that is, you don't need a telescope/binoculars to see it.

HIP86831 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD161270. The Id of the star in the Gould Star Catalogue is 169. 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 61 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 61 Ophiuchi, the location is 17h 44m 34.09 and +02d34`45.9 .

Proper Motion of 61 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 17.78 ± 4.91 miliarcseconds/year towards the north and 10.63 ± 7.81 miliarcseconds/year east if we saw them in the horizon.

Physical Properties (Colour, Temperature, Radius) of 61 Ophiuchi

61 Ophiuchi has a spectral type of A1IV-V. This means the star is a blue subgiant star. The star has a B-V Colour Index of 0.13 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 8,224 Kelvin.

61 Ophiuchi Radius has been calculated as being 3.81 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 2,649,827.49.km. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 2.28. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures.

61 Ophiuchi Apparent and Absolute Magnitudes

61 Ophiuchi has an apparent magnitude of 6.16 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 0.41 If you used the 2007 Parallax value, you would get an absolute magnitude of 1.52. 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 61 Ophiuchi

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 7.09 which gave the calculated distance to 61 Ophiuchi as 460.03 light years away from Earth or 141.04 parsecs. It would take a spaceship travelling at the speed of light, 460.03 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 11.79 which put 61 Ophiuchi at a distance of 276.64 light years or 84.82 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 Metallicity and/or Mass is from the E.U. Exoplanets. The information was obtained as of 12th Feb 2017.

61 Ophiuchi Facts

Alternative Names

Traditional/Proper Name61 Ophiuchi
Flamsteed Name61 Ophiuchi
Flamsteed Short Name61 Oph
Hipparcos Library I.D.86831
Bonner DurchmusterungBD+02 3390
Gould I.D.169
Henry Draper Designation161270

Visual Facts

Star Typesubgiant star
Absolute Magnitude0.41 / 1.52
Visual / Apparent Magnitude6.16
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)17h 44m 34.09
Declination (Dec.)+02d34`45.9
Galactic Latitude16.04 degrees
Galactic Longitude27.50 degrees
1997 Distance from Earth7.09 Parallax (milliarcseconds)
 460.03 Light Years
 141.04 Parsecs
2007 Revised Distance from Earth11.79 Parallax (milliarcseconds)
 276.64 Light Years
 84.82 Parsecs
Proper Motion Dec.17.78 ± 4.91 milliarcseconds/year
Proper Motion RA.10.63 ± 7.81 milliarcseconds/year
B-V Index0.13
Radial Velocity-31.50 ± 0.90 km/s
Spectral TypeA1IV-V
Colour(A) blue

Estimated Facts

Calculated Effective Temperature8,224 Kelvin

Sources and Links

SIMBAD SourceLink

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