Phecda (Gamma Ursae Majoris) is a blue main sequence dwarf star that can be located in the constellation of UrsaMajor. It is the 87th brightest star in the night sky. It is calculated at being 5.000 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,64 Ursae Majoris , 64 UMa.
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.
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 +53d41`41.0 .
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 011.01 ± 000.25 towards the north and 107.68 ± 000.40 east if we saw them in the horizon.
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.
Phecda has a spectral type of A0V SB. This means the star is a blue main sequence dwarf 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 9,025 Kelvin.
Phecda has been calculated as 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. The star's solar mass is 1.00 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 5.00 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 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.
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.
|Short Name||64 UMa|
|Bayer Designation||Gamma Ursae Majoris|
|Alternative Name(s)||Phad and Phekda,64 Ursae Majoris|
|Hipparcos Library I.D.||58001|
|Yale Bright Star Catalogue (HR) Id||4554|
|Bonner Durchmusterung||BD+54 1475|
|Henry Draper Designation||103287|
|Star Type||main sequence dwarf star|
|Age||5.000 Billions of Years|
|Absolute Magnitude||0.36 / 0.38|
|Right Ascension (R.A.)||11h 53m 49.74|
|1997 Distance from Earth||38.99 Parallax (milliarcseconds)|
|83.65 Light Years|
|2007 Revised Distance from Earth||39.21 Parallax (milliarcseconds)|
|83.18 Light Years|
|Proper Motion Dec.||11.01 ± 0.25 milliarcseconds/year|
|Proper Motion RA.||107.68 ± 0.40 milliarcseconds/year|
|Spectral Type||A0V SB|
|Brightest in Night Sky||87th|
|Radius (x the Sun)||3.24|
|Luminosity (x the Sun)||24.0000000|
|Calculated Effective Temperature||9,025 Kelvin|
|Mass Compared to the Sun||1.00|