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4 Herculis, HD142926, HIP77986, HR5938

4 Herculis is a blue eruptive star that can be located in the constellation of Hercules. The star can be seen with the naked eye, that is, you don't need a telescope/binoculars to see it.

The Id of the star in the Yale Bright Star Catalogue is HR5938. HIP77986 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD142926.

4 Herculis has alternative name(s), V839 Her.

Location of 4 Herculis

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 4 Herculis, the location is 15h 55m 30.61 and +42d 33` 58.1 .

Proper Motion of 4 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 16.65 ± 0.21 miliarcseconds/year towards the north and -23.10 ± 0.24 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 -20.20000 km/s with an error of about 0.30 km/s .

Physical Properties (Colour, Temperature, Radius) of 4 Herculis

4 Herculis has a spectral type of B9p. This means the star is a blue star. The star is 7362.00000000 Parsecs from the Galactic Centre or terms of Light Years is 24012.1453852800000000s. The star has a B-V Colour Index of -0.1 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 13,867 Kelvin.

4 Herculis Radius has been calculated as being 1.71 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 1,189,663.06.km. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 1.90. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures.

4 Herculis Apparent and Absolute Magnitudes

4 Herculis has an apparent magnitude of 5.73 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 -0.12 If you used the 2007 Parallax value, you would get an absolute magnitude of -0.35. 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 4 Herculis

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 6.77 which gave the calculated distance to 4 Herculis as 481.78 light years away from Earth or 147.71 parsecs. It would take a spaceship travelling at the speed of light, 481.78 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 6.08 which put 4 Herculis at a distance of 536.45 light years or 164.47 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*.

Variable Type of 4 Herculis

The star is a eruptive Gamma Cassiopeiae variable type which means that its size changes over time. The Variable Type is usually named after the first star of that type to be spotted. 4 Herculis brightness ranges from a magnitude of 5.856 to a magnitude of 5.685 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 0.2 days (variability).

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.

4 Herculis Facts

Alternative Names

Traditional/Proper Name4 Herculis
Flamsteed Name4 Herculis
Flamsteed Short Name4 Her
Short NameV839 Her
Hipparcos Library I.D.77986
Yale Bright Star Catalogue (HR) Id5938
Bonner DurchmusterungBD+42 2652
Henry Draper Designation142926

Visual Facts

Star Type star
Absolute Magnitude-0.12 / -0.35
Visual / Apparent Magnitude5.73
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)15h 55m 30.61
Declination (Dec.)+42d 33` 58.1
Galactic Latitude49.79 degrees
Galactic Longitude67.77 degrees
1997 Distance from Earth6.77 Parallax (milliarcseconds)
 481.78 Light Years
 147.71 Parsecs
2007 Revised Distance from Earth6.08 Parallax (milliarcseconds)
 536.45 Light Years
 164.47 Parsecs
Galacto-Centric Distance24,012.15 Light Years / 7,362.00 Parsecs
Proper Motion Dec.16.65 ± 0.21 milliarcseconds/year
Proper Motion RA.-23.10 ± 0.24 milliarcseconds/year
B-V Index-0.10
Radial Velocity-20.20 ± 0.30 km/s
Spectral TypeB9p
Colour(B) blue

Variable Star Details

Variable Star ClassEruptive
Variable Star TypeGamma Cassiopeiae
Mean Variability Period in Days0.206
Variable Magnitude Range (Brighter - Dimmer)5.685 - 5.856

Estimated Facts

Calculated Effective Temperature13,867 Kelvin

Sources and Links

SIMBAD SourceLink

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