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HO Pegasi, HD207932, HIP107956

HO Pegasi is a red pulsating giant star that can be located in the constellation of Pegasus. The star can be seen with the naked eye, that is, you don't need a telescope/binoculars to see it.

HIP107956 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD207932.

HO Pegasi has alternative name(s), HO Peg.

Location of HO 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 HO Pegasi, the location is 21h 52m 18.17 and +21d 16` 23.2 .

Proper Motion of HO 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 24.00 ± 0.29 miliarcseconds/year towards the north and 15.59 ± 0.34 miliarcseconds/year east if we saw them in the horizon.

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

HO Pegasi has a spectral type of M8III. This means the star is a red giant star. The star is 7347.00000000 Parsecs from the Galactic Centre or terms of Light Years is 23963.2208836800000000s. The star has a B-V Colour Index of 1.6 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 3,779 Kelvin.

HO Pegasi Radius has been calculated as being 47.44 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 33,010,388.69.km. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 33.28. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures.

HO Pegasi Apparent and Absolute Magnitudes

HO Pegasi has an apparent magnitude of 6.27 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 -1.69 If you used the 2007 Parallax value, you would get an absolute magnitude of -0.92. 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 HO Pegasi

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 2.56 which gave the calculated distance to HO Pegasi as 1274.08 light years away from Earth or 390.62 parsecs. It would take a spaceship travelling at the speed of light, 1274.08 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 3.64 which put HO Pegasi at a distance of 896.05 light years or 274.73 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 7,347.00 Parsecs or 23,963.22 Light Years. The Galacto-Centric Distance is the distance from the star to the Centre of the Galaxy which is Sagittarius A*.

Variable Type of HO Pegasi

The star is a pulsating Slow Irregular 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. HO Pegasi brightness ranges from a magnitude of 6.450 to a magnitude of 6.066 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 0.3 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 Metallicity and/or Mass is from the E.U. Exoplanets. The information was obtained as of 12th Feb 2017.

HO Pegasi Facts

Alternative Names

Traditional/Proper NameHO Pegasi
Short NameHO Peg
Hipparcos Library I.D.107956
Bonner DurchmusterungBD+20 5027
Henry Draper Designation207932

Visual Facts

Star Typegiant star
Absolute Magnitude-1.69 / -0.92
Visual / Apparent Magnitude6.27
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)21h 52m 18.17
Declination (Dec.)+21d 16` 23.2
Galactic Latitude-25.04 degrees
Galactic Longitude76.50 degrees
1997 Distance from Earth2.56 Parallax (milliarcseconds)
 1274.08 Light Years
 390.62 Parsecs
2007 Revised Distance from Earth3.64 Parallax (milliarcseconds)
 896.05 Light Years
 274.73 Parsecs
Galacto-Centric Distance23,963.22 Light Years / 7,347.00 Parsecs
Proper Motion Dec.24.00 ± 0.29 milliarcseconds/year
Proper Motion RA.15.59 ± 0.34 milliarcseconds/year
B-V Index1.60
Radial Velocity-21.24 ± 0.40 km/s
Spectral TypeM8III
Colour(M) Red

Variable Star Details

Variable Star ClassPulsating
Variable Star TypeSlow Irregular
Mean Variability Period in Days0.301
Variable Magnitude Range (Brighter - Dimmer)6.066 - 6.450

Estimated Facts

Calculated Effective Temperature3,779 Kelvin

Sources and Links

SIMBAD SourceLink

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