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HR Pegasi, HD216672, HIP113131

HR Pegasi is a pulsating 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.

HIP113131 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD216672.

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

Location of HR 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 HR Pegasi, the location is 22h 54m 35.62 and +16d56`30.7 .

Proper Motion of HR 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 -8.68 ± 0.22 miliarcseconds/year towards the north and 14.98 ± 0.39 miliarcseconds/year east if we saw them in the horizon.

Physical Properties (Temperature, Radius) of HR Pegasi

HR Pegasi has a spectral type of S5,1. This means the star is a star. The star is 7393.00000000 Parsecs from the Galactic Centre or terms of Light Years is 24113.2560219200000000s. The star has a B-V Colour Index of 1.72 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 3,379 Kelvin.

HR Pegasi Radius has been calculated as being 42.59 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 29,636,094.41.km. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 60.16. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures. The star's Iron Abundance is -0.19 with an error value of 9.99 Fe/H with the Sun has a value of 1 to put it into context.

HR Pegasi Apparent and Absolute Magnitudes

HR Pegasi has an apparent magnitude of 6.39 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 -0.97 If you used the 2007 Parallax value, you would get an absolute magnitude of -1.72. 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 HR Pegasi

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 3.37 which gave the calculated distance to HR Pegasi as 967.84 light years away from Earth or 296.74 parsecs. It would take a spaceship travelling at the speed of light, 967.84 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 2.39 which put HR Pegasi at a distance of 1364.70 light years or 418.41 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 7,393.00 Parsecs or 24,113.26 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 HR Pegasi

The star is a pulsating Semiregular late- (M, C, S or Me, Ce, Se) giants with poorly defined periodicity 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. HR Pegasi brightness ranges from a magnitude of 6.475 to a magnitude of 6.244 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 0.2 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.

HR Pegasi Facts

Alternative Names

Traditional/Proper NameHR Pegasi
Short NameHR Peg
Hipparcos Library I.D.113131
Bonner DurchmusterungBD+16 4833
Henry Draper Designation216672

Visual Facts

Star Type star
Absolute Magnitude-0.97 / -1.72
Visual / Apparent Magnitude6.39
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)22h 54m 35.62
Declination (Dec.)+16d56`30.7
Galactic Latitude-37.61 degrees
Galactic Longitude86.83 degrees
1997 Distance from Earth3.37 Parallax (milliarcseconds)
 967.84 Light Years
 296.74 Parsecs
2007 Revised Distance from Earth2.39 Parallax (milliarcseconds)
 1364.70 Light Years
 418.41 Parsecs
Galacto-Centric Distance24,113.26 Light Years / 7,393.00 Parsecs
Proper Motion Dec.-8.68 ± 0.22 milliarcseconds/year
Proper Motion RA.14.98 ± 0.39 milliarcseconds/year
B-V Index1.72
Radial Velocity10.60 ± 0.26 km/s
Iron Abundance-0.19 ± 9.99 Fe/H
Spectral TypeS5,1

Variable Star Details

Variable Star ClassPulsating
Variable Star TypeSemiregular late- (M, C, S or Me, Ce, Se) giants with poorly defined periodicity
Mean Variability Period in Days0.236
Variable Magnitude Range (Brighter - Dimmer)6.244 - 6.475

Estimated Facts

Calculated Effective Temperature3,379 Kelvin

Sources and Links

SIMBAD SourceLink

Related Stars


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