Universe Guide


Markab (Alpha Pegasi) - HD218045 - HIP113963 - HR8781

Markab (Alpha Pegasi) is a blue giant star that can be located in the constellation of Pegasus. It is the 91st brightest star in the night sky. Alpha Pegasi is the Bayer Classification for the star. The Id of the star in the Yale Bright Star Catalogue is HR8781. HIP113963 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD218045. Markab has alternative name(s), 54 Pegasi, Markab , 54 Peg. In Arabic, it is known as Mankib al-Faras.

Its name Markab is also shared with Tau Pegasi in the same constellation.

Location of Markab

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 Markab, the location is 23h 04m 45.62 and +15d12`19.3 .

Proper Motion of Markab

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 -041.30 ± 000.11 towards the north and 060.40 ± 000.19 east if we saw them in the horizon.

Physical Properties (Colour, Temperature, Radius) of Markab

Markab has a spectral type of B9.5III. This means the star is a blue giant star. The star has a B-V Colour Index of 0 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 9,531 Kelvin.

Markab has been calculated as 4.66 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 3,244,273.57.km.

Markab Apparent and Absolute Magnitudes

Markab has an apparent magnitude of 2.49 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 -0.67 If you used the 2007 Parallax value, you would get an absolute magnitude of -0.57. 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 Markab

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 23.36 which gave the calculated distance to Markab as 139.62 light years away from Earth or 42.81 parsecs. It would take a spaceship travelling at the speed of light, 139.62 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 24.46 which put Markab at a distance of 133.35 light years or 40.88 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.

Meteor Showers Radiating from near Markab

The Pegasids Meteor Shower radiants from a point near this star. The meteor shower runs typically between July 7-13 with a peak date of July 9th. The speed of a meteor in the shower is 70 Km/s. The amount of meteors predicted to be seen per hour (Zenith Hourly Rate) is 70.

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.

Markab Facts

Alternative Names

Traditional NameMarkab
Short Name54 Peg
Arabic NameMankib al-Faras
English Meaning'The shoulder' of the horse
Bayer DesignationAlpha Pegasi
Alternative Name(s)54 Pegasi, Markab
Hipparcos Library I.D.113963
Yale Bright Star Catalogue (HR) Id8781
Bonner DurchmusterungBD+14 4926
Henry Draper Designation218045

Visual Facts

Star Typegiant star
Absolute Magnitude-0.67 / -0.57
Apparent Magnitude2.49
Right Ascension (R.A.)23h 04m 45.62
Declination (Dec.)+15d12`19.3
1997 Distance from Earth23.36 Parallax (milliarcseconds)
 139.62 Light Years
 42.81 Parsecs
2007 Revised Distance from Earth24.46 Parallax (milliarcseconds)
 133.35 Light Years
 40.88 Parsecs
Proper Motion Dec.-41.30 ± 0.11 milliarcseconds/year
Proper Motion RA.60.40 ± 0.19 milliarcseconds/year
B-V Index0.00
Spectral TypeB9.5III
Brightest in Night Sky91st
Colour(B) blue

Estimated Facts

Radius (x the Sun)4.66
Calculated Effective Temperature9,531 Kelvin

Sources and Links

SIMBAD SourceLink

Related Stars

Location of Markab in Pegasus

Markab (Alpha Pegasi) Location in Pegasus

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

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