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Sigma Pegasi, 49 Pegasi, HD216385, HIP112935, HR8697

Sigma Pegasi is a blue to white 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. The star has an estimated age of 2.70 Billion of Years but could be as young as 2.60 to 2.80 according to Hipparcos.

Sigma Pegasi is the Bayer Classification for the star. The Id of the star in the Yale Bright Star Catalogue is HR8697. HIP112935 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD216385. The Id of the star in the Gould Star Catalogue is 39. Stars in the southern hemisphere are more likely to have a Gould Id than the northern hemisphere. For example, there are no Gould classified stars in Ursa Major.

Location of Sigma 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 Sigma Pegasi, the location is 22h 52m 23.77 and +09d 50` 08.0 .

Proper Motion of Sigma 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 42.65 ± 0.16 miliarcseconds/year towards the north and 521.04 ± 0.29 miliarcseconds/year east if we saw them in the horizon. The Radial Velocity, that is the speed at which the star is moving away/towards us is 11.50000 km/s with an error of about 0.20 km/s .

Physical Properties (Colour, Temperature, Age, Radius) of Sigma Pegasi

Sigma Pegasi has a spectral type of F7IV. This means the star is a blue to white star. The star is 7397.00000000 Parsecs from the Galactic Centre or terms of Light Years is 24126.3025556800000000s. The star has a B-V Colour Index of 0.48 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 6,369 Kelvin.

Sigma Pegasi Radius has been calculated as being 1.91 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 1,328,053.84.km. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 1.94. 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 -0.20 with an error value of 0.01 Fe/H with the Sun has a value of 1 to put it into context.

The stars age according to Hipparcos data files put the star at an age of about 2.70 Billion years old but could be between 2.60 and 2.80 Billion years old. In comparison, the Sun's age is about 4.6 Billion Years Old.

Sigma Pegasi Apparent and Absolute Magnitudes

Sigma Pegasi has an apparent magnitude of 5.16 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 3.02 If you used the 2007 Parallax value, you would get an absolute magnitude of 2.98. 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 Sigma Pegasi

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 37.25 which gave the calculated distance to Sigma Pegasi as 87.56 light years away from Earth or 26.85 parsecs. It would take a spaceship travelling at the speed of light, 87.56 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 36.66 which put Sigma Pegasi at a distance of 88.97 light years or 27.28 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 7,397.00 Parsecs or 24,126.30 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.

Sigma Pegasi Facts

Alternative Names

Flamsteed Name49 Pegasi
Flamsteed Short Name49 Peg
Bayer DesignationSigma Pegasi
Hipparcos Library I.D.112935
Yale Bright Star Catalogue (HR) Id8697
Bonner DurchmusterungBD+09 5122
Gould I.D.39
Henry Draper Designation216385

Visual Facts

Star Type star
Age2.70 Billion Years Old
Age Range2.60 - 2.80 Billion Years Old
Absolute Magnitude3.02 / 2.98
Visual / Apparent Magnitude5.16
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)22h 52m 23.77
Declination (Dec.)+09d 50` 08.0
Galactic Latitude-43.11 degrees
Galactic Longitude80.87 degrees
1997 Distance from Earth37.25 Parallax (milliarcseconds)
 87.56 Light Years
 26.85 Parsecs
2007 Revised Distance from Earth36.66 Parallax (milliarcseconds)
 88.97 Light Years
 27.28 Parsecs
Galacto-Centric Distance24,126.30 Light Years / 7,397.00 Parsecs
Proper Motion Dec.42.65 ± 0.16 milliarcseconds/year
Proper Motion RA.521.04 ± 0.29 milliarcseconds/year
B-V Index0.48
Radial Velocity11.50 ± 0.20 km/s
Iron Abundance-0.20 ± 0.01 Fe/H
Spectral TypeF7IV
Colour(F) blue to white

Estimated Facts

Calculated Effective Temperature6,369 Kelvin

Sources and Links

SIMBAD SourceLink

Related Stars

Multi-Star System

The star has been identified as being a multi-star system, one in which there is at least one star in close orbit to another star or two or more stars orbiting a central point. The stars may be of equal mass, unequal mass where one star is stronger than the other or be in groups orbiting a central point which doesn't necessarily have to be a star. More information can be found on my dedicated multiple star systems page. The source of the info is Simbad. The file is dated 2000 so any differences between this and any other source will be down to the actual source from where the information came from.

Proper Motion mas/yr
H.D. IdB.D. IdStar CodeMagnitudeR.A.Dec.SpectrumColourYear
216385+09 5122.0A5.20000522.0000044.00000F7Yellow/White

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