Universe Guide


Pi Pegasi - HD210459 - HIP109410

Pi Pegasi is a blue to white giant star that can be located in the constellation of Pegasus. Pi Pegasi is the Bayer Classification for the star. HIP109410 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD210459. Pi Pegasi has alternative name(s), 29 Pegasi , 29 Peg.

Location of Pi Pegasi

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 Pi Pegasi, the location is 22h 09m 59.25 and +33d10`41.8 .

Proper Motion of Pi Pegasi

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 -018.95 ± 000.13 towards the north and -012.87 ± 000.17 east if we saw them in the horizon.

Physical Properties (Colour, Temperature, Radius) of Pi Pegasi

Pi Pegasi has a spectral type of F5III. This means the star is a blue to white giant star. The star has a B-V Colour Index of 0.47 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 6,412 Kelvin.

Pi Pegasi has been calculated as 8.15 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 5,667,641.53.km.

Pi Pegasi Apparent and Absolute Magnitudes

Pi Pegasi has an apparent magnitude of 4.28 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 -0.16 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 Pi Pegasi

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 12.96 which gave the calculated distance to Pi Pegasi as 251.67 light years away from Earth or 77.16 parsecs. It would take a spaceship travelling at the speed of light, 251.67 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 12.40 which put Pi Pegasi at a distance of 263.03 light years or 80.65 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.

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.

Pi Pegasi Facts

Alternative Names

Short Name29 Peg
Bayer DesignationPi Pegasi
Alternative Name(s)29 Pegasi
Hipparcos Library I.D.109410
Bonner DurchmusterungBD+32 4352
Henry Draper Designation210459

Visual Facts

Star Typegiant star
Absolute Magnitude-0.16 / -0.25
Apparent Magnitude4.28
Right Ascension (R.A.)22h 09m 59.25
Declination (Dec.)+33d10`41.8
1997 Distance from Earth12.96 Parallax (milliarcseconds)
 251.67 Light Years
 77.16 Parsecs
2007 Revised Distance from Earth12.40 Parallax (milliarcseconds)
 263.03 Light Years
 80.65 Parsecs
Proper Motion Dec.-18.95 ± 0.13 milliarcseconds/year
Proper Motion RA.-12.87 ± 0.17 milliarcseconds/year
B-V Index0.47
Spectral TypeF5III
Colour(F) blue to white

Estimated Facts

Radius (x the Sun)8.15
Calculated Effective Temperature6,412 Kelvin

Sources and Links

SIMBAD SourceLink

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