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S Gruis, HD212539, HIP110736

S Gruis is a red pulsating giant star that can be located in the constellation of Grus. S Gruis is the brightest star in Grus based on the Hipparcos 2007 apparent magnitude. The star can not be seen by the naked eye, you need a telescope to see it.

HIP110736 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD212539.

S Gruis has alternative name(s), S Gru.

Location of S Gruis

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 S Gruis, the location is 22h 26m 05.45 and -48d26`18.7 .

Proper Motion of S Gruis

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 -6.82 ± 0.80 miliarcseconds/year towards the north and 23.04 ± 1.40 miliarcseconds/year east if we saw them in the horizon.

Physical Properties (Colour, Temperature, Radius) of S Gruis

S Gruis has a spectral type of M8III:e. This means the star is a red giant star. The star has a B-V Colour Index of 1.5 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 3,989 Kelvin.

S Gruis Radius has been calculated as being 9.14 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 6,362,730.94.km. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 5.36. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures.

S Gruis Apparent and Absolute Magnitudes

S Gruis has an apparent magnitude of 11.06 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 1.65 If you used the 2007 Parallax value, you would get an absolute magnitude of 2.81. 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 S Gruis

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 1.31 which gave the calculated distance to S Gruis as 2489.80 light years away from Earth or 763.36 parsecs. It would take a spaceship travelling at the speed of light, 2489.80 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 2.24 which put S Gruis at a distance of 1456.09 light years or 446.43 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 S Gruis

The star is a pulsating Omicron Ceti 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. S Gruis brightness ranges from a magnitude of 11.402 to a magnitude of 7.019 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 396.0 days (variability).

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.

S Gruis Facts

Alternative Names

Traditional/Proper NameS Gruis
Short NameS Gru
Hipparcos Library I.D.110736
Henry Draper Designation212539

Visual Facts

Star Typegiant star
Absolute Magnitude1.65 / 2.81
Visual / Apparent Magnitude11.06
Naked Eye VisibleRequires a 4.5 - 6 Inch Telescope - Magnitudes
Right Ascension (R.A.)22h 26m 05.45
Declination (Dec.)-48d26`18.7
Galactic Latitude-54.77 degrees
Galactic Longitude345.88 degrees
1997 Distance from Earth1.31 Parallax (milliarcseconds)
 2489.80 Light Years
 763.36 Parsecs
2007 Revised Distance from Earth2.24 Parallax (milliarcseconds)
 1456.09 Light Years
 446.43 Parsecs
Proper Motion Dec.-6.82 ± 0.80 milliarcseconds/year
Proper Motion RA.23.04 ± 1.40 milliarcseconds/year
B-V Index1.50
Radial Velocity-12.10 ± 3.40 km/s
Spectral TypeM8III:e
Colour(M) Red

Variable Star Details

Variable Star ClassPulsating
Variable Star TypeOmicron Ceti
Mean Variability Period in Days396.000
Variable Magnitude Range (Brighter - Dimmer)7.019 - 11.402

Estimated Facts

Calculated Effective Temperature3,989 Kelvin

Sources and Links

SIMBAD SourceLink

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