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Matar (Eta Pegasi) - HD215182 - HIP112158 - HR8650

Matar (Eta Pegasi) is a white to yellow 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.

Eta Pegasi is the Bayer Classification for the star. The Id of the star in the Yale Bright Star Catalogue is HR8650. HIP112158 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD215182.

Matar has alternative name(s), 44 Pegasi , 44 Peg. In Arabic, it is known as Sa'd Matar.

Location of Matar

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 Matar, the location is 22h 43m 00.13 and +30d13`16.7 .

Proper Motion of Matar

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 -25.67 ± 0.46 miliarcseconds/year towards the north and 13.16 ± 0.71 miliarcseconds/year east if we saw them in the horizon.

Physical Properties (Colour, Temperature, Radius) of Matar

Matar has a spectral type of G2II-III... This means the star is a white to yellow giant star. The star is 7403.00000000 Parsecs from the Galactic Centre or terms of Light Years is 24145.8723563200000000s. The star has a B-V Colour Index of 0.85 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 5,164 Kelvin.

Matar Radius has been calculated as being 19.90 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 13,849,265.83.km. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 19.90. 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 -0.13 with an error value of 9.99 Fe/H with the Sun has a value of 1 to put it into context.

Matar Apparent and Absolute Magnitudes

Matar has an apparent magnitude of 2.93 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 -1.16 If you used the 2007 Parallax value, you would get an absolute magnitude of -1.16. 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 Matar

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 15.18 which gave the calculated distance to Matar as 214.86 light years away from Earth or 65.88 parsecs. It would take a spaceship travelling at the speed of light, 214.86 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 15.22 which put Matar at a distance of 214.30 light years or 65.70 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 7,403.00 Parsecs or 24,145.87 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.

Matar Facts

Alternative Names

Traditional/Proper NameMatar
Short Name44 Peg
Arabic NameSa'd Matar
English MeaningThe lucky star of 'the rain'
Bayer DesignationEta Pegasi
Alternative Name(s)44 Pegasi
Hipparcos Library I.D.112158
Yale Bright Star Catalogue (HR) Id8650
Bonner DurchmusterungBDD+29 4741
Henry Draper Designation215182

Visual Facts

Star Typegiant star
Absolute Magnitude-1.16 / -1.16
Visual / Apparent Magnitude2.93
Naked Eye VisibleYes - Ref: Wiki
Right Ascension (R.A.)22h 43m 00.13
Declination (Dec.)+30d13`16.7
Galactic Latitude-24.95 degrees
Galactic Longitude92.50 degrees
1997 Distance from Earth15.18 Parallax (milliarcseconds)
 214.86 Light Years
 65.88 Parsecs
2007 Revised Distance from Earth15.22 Parallax (milliarcseconds)
 214.30 Light Years
 65.70 Parsecs
Galacto-Centric Distance24,145.87 Light Years / 7,403.00 Parsecs
Proper Motion Dec.-25.67 ± 0.46 milliarcseconds/year
Proper Motion RA.13.16 ± 0.71 milliarcseconds/year
B-V Index0.85
Radial Velocity4.17 ± 0.35 km/s
Iron Abundance-0.13 ± 9.99 Fe/H
Eccentricity0.15
Inclination70.58
Semi-Major Axis13.60
Orbital Period (Days)818.00
Argument Of Periastron5.61
Spectral TypeG2II-III..
Colour(G) White to Yellow

Estimated Facts

Calculated Effective Temperature5,164 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
215182+29 4741.0A3.1000013.00000-21.00000G0Yellow
+29 4740.0B1.000000.000001824
BC10.100001889
BD14.000001916
DE16.000001916

Location of Matar in Pegasus


Matar (Eta Pegasi) Location in Pegasus

The map was generated using Night Vision, an awesome free application by Brian Simpson.


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