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RS Gruis - HD206379 - HIP107231

RS Gruis is a blue pulsating subgiant star that can be located in the constellation of Grus. The star can not be seen by the naked eye, you need a telescope to see it. The star has an estimated age of 1.20 Billion of Years but could be as young as 1.10 to 1.30 according to Hipparcos.

HIP107231 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD206379.

RS Gruis has alternative name(s), RS_Gru.

Location of RS 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 RS Gruis, the location is 21h 43m 04.28 and -48d11`22.0 .

Proper Motion of RS 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 -18.83 ± 0.66 miliarcseconds/year towards the north and -70.16 ± 1.23 miliarcseconds/year east if we saw them in the horizon.

Physical Properties (Colour, Temperature, Age, Radius) of RS Gruis

RS Gruis has a spectral type of A9IV. This means the star is a blue subgiant star. The star has a B-V Colour Index of 0.26 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 7,428 Kelvin.

RS Gruis Radius has been calculated as being 2.81 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 1,957,173.00.km. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 2.96. 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 -0.25 with an error value of 9.99 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 1.20 Billion years old but could be between 1.10 and 1.30 Billion years old. In comparison, the Sun's age is about 4.6 Billion Years Old.

RS Gruis Apparent and Absolute Magnitudes

RS Gruis has an apparent magnitude of 8.28 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 1.51 If you used the 2007 Parallax value, you would get an absolute magnitude of 1.40. 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 RS Gruis

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 4.42 which gave the calculated distance to RS Gruis as 737.93 light years away from Earth or 226.24 parsecs. It would take a spaceship travelling at the speed of light, 737.93 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 4.20 which put RS Gruis at a distance of 776.58 light years or 238.10 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 RS Gruis

The star is a pulsating Phenomenologically, these resemble DSCT (Delta Sct) s and are pulsating subdwarfs of the spherical component, or old disk galactic population, with spectral s in the range A2-F5 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. RS Gruis brightness ranges from a magnitude of 9.000 to a magnitude of 8.000 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.

RS Gruis Facts

Alternative Names

Traditional/Proper NameRS Gruis
Short NameRS Gru
Hipparcos Library I.D.107231
Henry Draper Designation206379

Visual Facts

Star Typesubgiant star
Age1.20 Billion Years Old
Age Range1.10 - 1.30 Billion Years Old
Absolute Magnitude1.51 / 1.40
Visual / Apparent Magnitude8.28
Naked Eye VisibleRequires a 7x50 Binoculars - Ref: Wiki
Right Ascension (R.A.)21h 43m 04.28
Declination (Dec.)-48d11`22.0
Galactic Latitude-48.06 degrees
Galactic Longitude349.87 degrees
1997 Distance from Earth4.42 Parallax (milliarcseconds)
 737.93 Light Years
 226.24 Parsecs
2007 Revised Distance from Earth4.20 Parallax (milliarcseconds)
 776.58 Light Years
 238.10 Parsecs
Proper Motion Dec.-18.83 ± 0.66 milliarcseconds/year
Proper Motion RA.-70.16 ± 1.23 milliarcseconds/year
B-V Index0.26
Radial Velocity62.20 ± 2.80 km/s
Iron Abundance-0.25 ± 9.99 Fe/H
Spectral TypeA9IV
Colour(A) blue

Variable Star Details

Variable Star ClassPulsating
Variable Star TypePhenomenologically, these resemble DSCT (Delta Sct) s and are pulsating subdwarfs of the spherical component, or old disk galactic population, with spectral s in the range A2-F5
Variable Magnitude Range (Brighter - Dimmer)8.000 - 9.000

Estimated Facts

Calculated Effective Temperature7,428 Kelvin

Sources and Links

SIMBAD SourceLink

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