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Upsilon Pegasi, 68 Pegasi, HD220657, HIP115623

Upsilon Pegasi is a blue to white subgiant star that can be located in the constellation of Pegasus. Upsilon Pegasi is the brightest star in Pegasus based on the Hipparcos 2007 apparent magnitude. The star can be seen with the naked eye, that is, you don't need a telescope/binoculars to see it.

Upsilon Pegasi is the Bayer Classification for the star. HIP115623 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD220657.

Location of Upsilon 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 Upsilon Pegasi, the location is 23h 25m 22.66 and +23d24`14.4 .

Proper Motion of Upsilon 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 36.12 ± 0.12 miliarcseconds/year towards the north and 192.19 ± 0.18 miliarcseconds/year east if we saw them in the horizon.

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

Upsilon Pegasi has a spectral type of F8IV. This means the star is a blue to white subgiant star. The star is 7407.00000000 Parsecs from the Galactic Centre or terms of Light Years is 24158.9188900800000000s. The star has a B-V Colour Index of 0.61 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 5,859 Kelvin.

Upsilon Pegasi Radius has been calculated as being 6.30 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 4,382,612.55.km. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 6.18. 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 -0.01 with an error value of 0.04 Fe/H with the Sun has a value of 1 to put it into context.

Upsilon Pegasi Apparent and Absolute Magnitudes

Upsilon Pegasi has an apparent magnitude of 4.42 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 0.79 If you used the 2007 Parallax value, you would get an absolute magnitude of 0.83. 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 Upsilon Pegasi

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 18.83 which gave the calculated distance to Upsilon Pegasi as 173.21 light years away from Earth or 53.11 parsecs. It would take a spaceship travelling at the speed of light, 173.21 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 19.14 which put Upsilon Pegasi at a distance of 170.41 light years or 52.25 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 7,407.00 Parsecs or 24,158.92 Light Years. The Galacto-Centric Distance is the distance from the star to the Centre of the Galaxy which is Sagittarius A*.

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.

Upsilon Pegasi Facts

Alternative Names

Flamsteed Name68 Pegasi
Flamsteed Short Name68 Peg
Bayer DesignationUpsilon Pegasi
Hipparcos Library I.D.115623
Bonner DurchmusterungBD+22 4833
Henry Draper Designation220657

Visual Facts

Star Typesubgiant star
Absolute Magnitude0.79 / 0.83
Visual / Apparent Magnitude4.42
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)23h 25m 22.66
Declination (Dec.)+23d24`14.4
Galactic Latitude-35.36 degrees
Galactic Longitude98.56 degrees
1997 Distance from Earth18.83 Parallax (milliarcseconds)
 173.21 Light Years
 53.11 Parsecs
2007 Revised Distance from Earth19.14 Parallax (milliarcseconds)
 170.41 Light Years
 52.25 Parsecs
Galacto-Centric Distance24,158.92 Light Years / 7,407.00 Parsecs
Proper Motion Dec.36.12 ± 0.12 milliarcseconds/year
Proper Motion RA.192.19 ± 0.18 milliarcseconds/year
B-V Index0.61
Radial Velocity-14.60 ± 2.00 km/s
Iron Abundance-0.01 ± 0.04 Fe/H
Spectral TypeF8IV
Colour(F) blue to white

Estimated Facts

Calculated Effective Temperature5,859 Kelvin

Sources and Links

SIMBAD SourceLink

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