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Gamma Microscopii - HD199951 - HIP103738

Gamma Microscopii is a white to yellow giant star that can be located in the constellation of Microscopium. Gamma Microscopii is the 1st brightest star in Microscopium 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.

Gamma Microscopii is the Bayer Classification for the star. HIP103738 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD199951.

Location of Gamma Microscopii

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 Gamma Microscopii, the location is 21h 01m 17.46 and -32d15`28.0 .

Proper Motion of Gamma Microscopii

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 0.41 ± 0.15 miliarcseconds/year towards the north and -1.73 ± 0.26 miliarcseconds/year east if we saw them in the horizon.

Gamma Microscopii Luminosity

Luminosity is the amount of energy that a star pumps out and its relative to the amount that our star, the Sun gives out. The figure of 113.0000000 that I have given is based on the Spectral Types page that I have found on the Internet. You might find a different figure, one that may have been calculated rather than generalised that I have done. The figure is always the amount times the luminosity of the Sun. It is an imprecise figure because of a number of factors including but not limited to whether the star is a variable star and distance.

Physical Properties (Colour, Temperature, Radius) of Gamma Microscopii

Gamma Microscopii has a spectral type of G8III. This means the star is a white to yellow giant star. The star is 7348.00000000 Parsecs from the Galactic Centre or terms of Light Years is 23966.4825171200000000s. The star has a B-V Colour Index of 0.89 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 5,074 Kelvin.

Gamma Microscopii Radius has been calculated as being 9.64 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 6,709,375.43.km. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 9.87. 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 -0.14 with an error value of 0.06 Fe/H with the Sun has a value of 1 to put it into context.

Gamma Microscopii Apparent and Absolute Magnitudes

Gamma Microscopii has an apparent magnitude of 4.67 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 0.49 If you used the 2007 Parallax value, you would get an absolute magnitude of 0.44. 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 Gamma Microscopii

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 14.59 which gave the calculated distance to Gamma Microscopii as 223.55 light years away from Earth or 68.54 parsecs. It would take a spaceship travelling at the speed of light, 223.55 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 14.24 which put Gamma Microscopii at a distance of 229.05 light years or 70.22 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 7,348.00 Parsecs or 23,966.48 Light Years. The Galacto-Centric Distance is the distance from the star to the Centre of the Galaxy which is Sagittarius A*. Gamma Microscopii brightness ranges from a magnitude of 5.000 to a magnitude of 5.000 over its variable period. The smaller the magnitude, the brighter the star.

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.

Gamma Microscopii Facts

Alternative Names

Bayer DesignationGamma Microscopii
Hipparcos Library I.D.103738
Henry Draper Designation199951

Visual Facts

Star Typegiant star
Absolute Magnitude0.49 / 0.44
Visual / Apparent Magnitude4.67
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)21h 01m 17.46
Declination (Dec.)-32d15`28.0
Galactic Latitude-40.34 degrees
Galactic Longitude12.34 degrees
1997 Distance from Earth14.59 Parallax (milliarcseconds)
 223.55 Light Years
 68.54 Parsecs
2007 Revised Distance from Earth14.24 Parallax (milliarcseconds)
 229.05 Light Years
 70.22 Parsecs
Galacto-Centric Distance23,966.48 Light Years / 7,348.00 Parsecs
Proper Motion Dec.0.41 ± 0.15 milliarcseconds/year
Proper Motion RA.-1.73 ± 0.26 milliarcseconds/year
B-V Index0.89
Radial Velocity17.60 ± 0.80 km/s
Iron Abundance-0.14 ± 0.06 Fe/H
Spectral TypeG8III
Colour(G) White to Yellow

Variable Star Details

Estimated Facts

Luminosity (x the Sun)113.0000000
Calculated Effective Temperature5,074 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
199951-3216353.2A4.700000.000008.00000G4Yellow
B13.700001945

Location of Gamma Microscopii in Microscopium


Gamma Microscopii (Gamma Microscopii) Location in Microscopium

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


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