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Sigma Virginis - HD115521 - HIP64852

Sigma Virginis is a red pulsating giant star that can be located in the constellation of Virgo. Sigma Virginis is the Bayer Classification for the star. HIP64852 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD115521. The Id of the star in the Gould Star Catalogue is 130. 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. Sigma Virginis has alternative name(s), 60 Virginis , NSV_06173, 60 Vir.

Location of Sigma Virginis

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 Virginis, the location is 13h 17m 36.29 and +05d28`11.4 .

Proper Motion of Sigma Virginis

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 009.14 ± 000.12 towards the north and -006.06 ± 000.19 east if we saw them in the horizon.

Sigma Virginis 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 11.0000000 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 Sigma Virginis

Sigma Virginis has a spectral type of M2III. This means the star is a red giant star. The star has a B-V Colour Index of 1.63 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 3,700 Kelvin.

Sigma Virginis has been calculated as 41.74 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 29,040,048.76.km.

Sigma Virginis Apparent and Absolute Magnitudes

Sigma Virginis has an apparent magnitude of 4.78 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 -1.32 If you used the 2007 Parallax value, you would get an absolute magnitude of -1.80. 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 Virginis

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 6.03 which gave the calculated distance to Sigma Virginis as 540.90 light years away from Earth or 165.84 parsecs. It would take a spaceship travelling at the speed of light, 540.90 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 4.83 which put Sigma Virginis at a distance of 675.29 light years or 207.04 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.

Variable Type of Sigma Virginis

The star is a pulsating Semiregular s, which are giants or supergiants of intermediate and late spectral 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. Sigma Virginis 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 Stellar Age, Metallicity or Mass is from the E.U. Exoplanets. The information was obtained as of 12th Feb 2017.

Sigma Virginis Facts

Alternative Names

Short NameNSV 06173, 60 Vir
Bayer DesignationSigma Virginis
Alternative Name(s)60 Virginis
Hipparcos Library I.D.64852
Bonner DurchmusterungBD+06 2722
Gould I.D.130
Henry Draper Designation115521

Visual Facts

Star Typegiant star
Absolute Magnitude-1.32 / -1.80
Apparent Magnitude4.78
Right Ascension (R.A.)13h 17m 36.29
Declination (Dec.)+05d28`11.4
1997 Distance from Earth6.03 Parallax (milliarcseconds)
 540.90 Light Years
 165.84 Parsecs
2007 Revised Distance from Earth4.83 Parallax (milliarcseconds)
 675.29 Light Years
 207.04 Parsecs
Proper Motion Dec.9.14 ± 0.12 milliarcseconds/year
Proper Motion RA.-6.06 ± 0.19 milliarcseconds/year
B-V Index1.63
Spectral TypeM2III
Colour(M) Red

Variable Star Details

Variable Star ClassPulsating
Variable Star TypeSemiregular s, which are giants or supergiants of intermediate and late spectral

Estimated Facts

Radius (x the Sun)41.74
Luminosity (x the Sun)11.0000000
Calculated Effective Temperature3,700 Kelvin

Sources and Links

SIMBAD SourceLink

Related Stars


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