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Phecda, Gamma Ursae Majoris, 64 Ursae Majoris, HD103287, HIP58001, HR4554

Phecda (Gamma Ursae Majoris) is a blue star that can be located in the constellation of UrsaMajor. Phecda is the 87th brightest star in the night sky and the 6th brightest star in Ursa Major based on the Hipparcos 2007 apparent magnitude. The star can be seen with the naked eye, that is, you don't need a telescope/binoculars to see it. It is calculated at being 4.604 Billion Years old. This information comes from ExoPlanet.

Gamma Ursae Majoris is the Bayer Classification for the star. The Id of the star in the Yale Bright Star Catalogue is HR4554. HIP58001 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD103287.

Phecda has alternative name(s), Phad and Phekda , .

Phecda is one of the major stars in the Ursa Majorconstellation or the Greater Bear as it is also known. It is fairly easy to identify given that the constellation can look like a saucepan. If you do imagine it is a saucepan for the moment, Phecda is at the bottom left of the pan, forgetting the legs. Once you have identified the constellation, it is pretty easy to identify all the other stars.

Location of Phecda

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 Phecda, the location is 11h 53m 49.74 and +53d 41` 41.0 .

Proper Motion of Phecda

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 11.01 ± 0.25 miliarcseconds/year towards the north and 107.68 ± 0.40 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 -11.90000 km/s with an error of about 0.70 km/s .

Phecda Luminosity

Luminosity is the amount of energy that a star pumps out and its relative to the amount that our star, the Sun gives out. The figure of 24.0000000 that I have given is based on the Spectral Types page that I have found on the Internet. You might find a different figure, one that may have been calculated rather than generalised that I have done. The figure is always the amount times the luminosity of the Sun. It is an imprecise figure because of a number of factors including but not limited to whether the star is a variable star and distance.

Physical Properties (Colour, Temperature, Age, Mass, Radius) of Phecda

Phecda has a spectral type of A0V SB. This means the star is a blue star. The star is 7410.00000000 Parsecs from the Galactic Centre or terms of Light Years is 24168.7037904000000000s. 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 9,025 Kelvin.

Phecda Radius has been calculated as being 3.24 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 2,251,592.92.km. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 3.21. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures. The star's solar mass is 1.23 times that of the Sun's. The Sun's Mass is 1,989,100,000,000,000,000,000 billion kg. which to calculate using this website is too large. To give idea of size, the Sun is 99.86% the mass of the solar system.

The star's metallicity is -0.250000, this value is the fractional amount of the star that is not Hydrogen (X) or Helium (Y). An older star would have a high metallicity whereas a new star would have a lower one.

The star is believed to be about 4.60 Billion years old. To put in context, the Sun is believed to be about five billion years old and the Universe is about 13.8 billion years old.

Phecda Apparent and Absolute Magnitudes

Phecda has an apparent magnitude of 2.41 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 0.36 If you used the 2007 Parallax value, you would get an absolute magnitude of 0.38. 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 Phecda

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 38.99 which gave the calculated distance to Phecda as 83.65 light years away from Earth or 25.65 parsecs. It would take a spaceship travelling at the speed of light, 83.65 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 39.21 which put Phecda at a distance of 83.18 light years or 25.50 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 7,410.00 Parsecs or 24,168.70 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.

Phecda Facts

Alternative Names

Traditional/Proper NamePhecda
Flamsteed Name64 Ursae Majoris
Flamsteed Short Name64 UMa
Bayer DesignationGamma Ursae Majoris
Alternative Name(s)Phad and Phekda
Hipparcos Library I.D.58001
Yale Bright Star Catalogue (HR) Id4554
Bonner DurchmusterungBD+54 1475
Henry Draper Designation103287

Visual Facts

Star Type star
ConstellationUrsa Major
Age4.60 Billion Years Old
Absolute Magnitude0.36 / 0.38
Visual / Apparent Magnitude2.41
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)11h 53m 49.74
Declination (Dec.)+53d 41` 41.0
Galactic Latitude61.38 degrees
Galactic Longitude140.84 degrees
1997 Distance from Earth38.99 Parallax (milliarcseconds)
 83.65 Light Years
 25.65 Parsecs
2007 Revised Distance from Earth39.21 Parallax (milliarcseconds)
 83.18 Light Years
 25.50 Parsecs
Galacto-Centric Distance24,168.70 Light Years / 7,410.00 Parsecs
Proper Motion Dec.11.01 ± 0.25 milliarcseconds/year
Proper Motion RA.107.68 ± 0.40 milliarcseconds/year
B-V Index0.04
Radial Velocity-11.90 ± 0.70 km/s
Iron Abundance-0.44 ± 9.99 Fe/H
Spectral TypeA0V SB
Brightest in Night Sky87th
Colour(A) blue

Estimated Facts

Luminosity (x the Sun)24.0000000
Calculated Effective Temperature9,025 Kelvin
Mass Compared to the Sun1.23

Sources and Links

SIMBAD SourceLink

Related Stars

Location of Phecda in Ursa Major

Phecda (Gamma Ursae Majoris) Location in Ursa Major

The map was generated using Night Vision, an awesome free application by Brian Simpson.

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