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100 Herculis, 100 Herculis B, HD166045, HIP88818, HR6781

100 Herculis is a blue main sequence dwarf star that can be located in the constellation of Hercules. 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.

100 Herculis's Alternative Names

The Id of the star in the Yale Bright Star Catalogue is HR6781. HIP88818 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD166045.

Flamsteed designations are named after the creator, Sir John Flamsteed. Sir John numbered the stars in the constellation with a number and the latin name, this star's Flamsteed designation is 100 Herculis B with it shortened to 10 Her B.

BD number is the number that the star was filed under in the Durchmusterung or Bonner Durchmusterung, a star catalogue that was put together by the Bonn Observatory between 1859 to 1903. The star's BD Number is BD+26 3178.

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

Location of 100 Herculis

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 100 Herculis, the location is 18h 07m 49.56 and +26° 06` 04.4 .

Proper Motion of 100 Herculis

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 21.94 ± 2.43 miliarcseconds/year towards the north and -4.98 ± 3.27 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 -17.00000 km/s with an error of about 4.30 km/s .

Physical Properties (Colour, Temperature) of 100 Herculis

100 Herculis has a spectral type of A3V. This means the star is a blue main sequence dwarf star. The star is 7,362.00 Parsecs from the Galactic Centre or terms of Light Years is 24,012.15 s. The star has a B-V Colour Index of 0.15 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 8,084 Kelvin.

100 Herculis Radius has been calculated as being 2.28 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 1,585,329.40.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 1.61. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures.

100 Herculis Apparent and Absolute Magnitudes

100 Herculis has an apparent magnitude of 5.83 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 1.60 If you used the 2007 Parallax value, you would get an absolute magnitude of 2.35. 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 100 Herculis

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 14.27 which gave the calculated distance to 100 Herculis as 228.57 light years away from Earth or 70.08 parsecs. It would take a spaceship travelling at the speed of light, 228.57 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 20.16 which put 100 Herculis at a distance of 161.79 light years or 49.60 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 7,362.00 Parsecs or 24,012.15 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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100 Herculis Facts

Visual Facts


 100 Herculis
Alternative NamesHD 166045, HIP 88818, HR 6781, 100 Herculis B, 10 Her B, BD+26 3178
Spectral TypeA3V
Multiple Star SystemYes
Star Type main sequence Dwarf Star
Colour blue
GalaxyMilky Way
ConstellationHercules
Absolute Magnitude1.60 / 2.35
Visual / Apparent Magnitude5.83
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)18h 07m 49.56
Declination (Dec.)+26° 06` 04.4
Galactic Latitude20.60 degrees
Galactic Longitude52.54 degrees
1997 Distance from Earth14.27 Parallax (milliarcseconds)
 228.57 Light Years
 70.08 Parsecs
2007 Distance from Earth20.16 Parallax (milliarcseconds)
 161.79 Light Years
 49.60 Parsecs
Galacto-Centric Distance24,012.15 Light Years / 7,362.00 Parsecs
Proper Motion Dec.21.94 ± 2.43 milliarcseconds/year
Proper Motion RA.-4.98 ± 3.27 milliarcseconds/year
B-V Index0.15
Radial Velocity-17.00 ± 4.30 km/s
Eccentricity0.05
Semi-Major Axis7697.00
Associated / Clustered Stars100 Herculis B

Companions (Multi-Star and Exoplanets) Facts


Exoplanet CountNone/Unaware

Estimated Facts


Calculated Effective Temperature8,084 Kelvin

Sources and Links


SIMBAD SourceLink

Related Stars


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