Universe Guide

HomeFactsConstellationsHercules

Phi Herculis - HD145389 - HIP79101

Phi Herculis is a blue rotating star that can be located in the constellation of Hercules. Phi Herculis is the Bayer Classification for the star. HIP79101 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD145389. Phi Herculis has alternative name(s), 11 Herculis , phi_Her, 11 Her.

Location of Phi 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 Phi Herculis, the location is 16h 08m 46.20 and +44d56`05.3 .

Proper Motion of Phi 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 036.76 ± 000.41 towards the north and -026.63 ± 000.45 east if we saw them in the horizon.

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

Phi Herculis has a spectral type of B9MNp.... This means the star is a blue star. The star has a B-V Colour Index of -0.04 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 11,437 Kelvin.

Phi Herculis has been calculated as 2.38 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 1,654,868.88.km.

Phi Herculis Apparent and Absolute Magnitudes

Phi Herculis has an apparent magnitude of 4.23 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 0.00 If you used the 2007 Parallax value, you would get an absolute magnitude of 0.25. 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 Phi 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 Phi 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 15.99 which put Phi Herculis at a distance of 203.98 light years or 62.54 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.

Variable Type of Phi Herculis

The star is a rotating Alpha2 Canum Venaticorum 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. This is a some uncertainty as to the type but the type mentioned is the current variable star classification for this star. Phi Herculis brightness ranges from a magnitude of 4.000 to a magnitude of 4.000 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 7.0 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 Stellar Age, Metallicity or Mass is from the E.U. Exoplanets. The information was obtained as of 12th Feb 2017.

Phi Herculis Facts

Alternative Names

Short Namephi Her, 11 Her
Bayer DesignationPhi Herculis
Alternative Name(s)11 Herculis
Hipparcos Library I.D.79101
Bonner DurchmusterungBD+45 2376
Henry Draper Designation145389

Visual Facts

Star Type star
Absolute Magnitude0.00 / 0.25
Apparent Magnitude4.23
Right Ascension (R.A.)16h 08m 46.20
Declination (Dec.)+44d56`05.3
1997 Distance from Earth14.27 Parallax (milliarcseconds)
 228.57 Light Years
 70.08 Parsecs
2007 Revised Distance from Earth15.99 Parallax (milliarcseconds)
 203.98 Light Years
 62.54 Parsecs
Proper Motion Dec.36.76 ± 0.41 milliarcseconds/year
Proper Motion RA.-26.63 ± 0.45 milliarcseconds/year
B-V Index-0.04
Eccentricity0.47
Inclination36.22
Semi-Major Axis9.09
Orbital Period (Days)560.50
Argument Of Periastron357.00
Spectral TypeB9MNp...
Colour(B) blue

Variable Star Details

Variable Star ClassRotating
Variable Star TypeAlpha2 Canum Venaticorum probably
Mean Variability Period in Days7.000

Estimated Facts

Radius (x the Sun)2.38
Calculated Effective Temperature11,437 Kelvin

Sources and Links

SIMBAD SourceLink

Related Stars


Add a Comment


Name:
Email: (Optional)
Comment: