Universe Guide

Mu2 Gruis

Mu2 Gruis Facts

  • Mu2 Gruis is a giant star that can be located in the constellation of Grus. The description is based on the spectral class.
  • Mu2 Gruis is not part of the constellation outline but is within the borders of the constellation.
  • Based on the spectral type (G8III) of the star, the star's colour is yellow .
  • The star can be seen with the naked eye, that is, you don't need a telescope/binoculars to see it.
  • Using the most recent figures given by the 2007 Hipparcos data, the star is 265.39 light years away from us. Distance

Mu2 Gruis's Alternative Names

Mu2 Gruis (Mu.02 Gru) is the Bayer Classification for the star. The Bayer Classification was created by Johann Bayer in 1603. The brightest star in the constellation is normally given the Alpha designation, there are exceptions such as Pollux which is Beta Geminorum.

The Id of the star in the Yale Bright Star Catalogue is HR8488. HIP109973 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD211202.

More details on objects' alternative names can be found at Star Names .

Location of Mu2 Gruis

The location of the giant star in the night sky 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 object is compared to the celestial equator and is expressed in degrees. For Mu2 Gruis, the location is 22h 16m 26.57 and -41° 37` 37.9 .

Radial Velocity and Proper Motion of Mu2 Gruis

Proper Motion

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 -6.72 ± 0.51 milliarcseconds/year towards the north and -12.57 ± 0.64 milliarcseconds/year east if we saw them in the horizon.

Radial Velocity

The Radial Velocity, that is the speed at which the star is moving away/towards the Sun is 12.50000 km/s with an error of about 0.80 km/s . When the value is negative then the star and the Sun are getting closer to one another, likewise, a positive number means that two stars are moving away. Its nothing to fear as the stars are so far apart, they won't collide in our life-time, if ever.

Physical Properties of Mu2 Gruis

Mu2 Gruis Colour and Temperature

Based on the star's spectral type of G8III , Mu2 Gruis's colour and type is yellow giant star. The star has a B-V Colour Index of 0.93 which means the star's temperature is about 4,989 Kelvin. The temperature was calculated using information from Morgans @ Uni.edu.

Mu2 Gruis 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 67.81 that I have given is based on the value in the Simbad Hipparcos Extended Catalogue at the University of Strasbourg from 2012.

Mu2 Gruis Radius

Mu2 Gruis estimated radius has been calculated as being 8.73 times bigger than the Sun. The Sun's radius is 695,800km, therefore the star's radius is an estimated 6,072,299.23.km. If you need the diameter of the star, you just need to multiple the radius by 2. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 9.657637500237277478842609664. The figure is derived at by using the formula from SDSS rather than peer reviewed papers. It has been known to produce widely incorrect figures.

Mu2 Gruis Apparent and Absolute Magnitudes

Mu2 Gruis has an apparent magnitude of 5.11 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 0.78 If you used the 2007 Parallax value, you would get an absolute magnitude of 0.56. 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 Mu2 Gruis

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 13.61000 which gave the calculated distance to Mu2 Gruis as 239.65 light years away from Earth or 73.48 parsecs. If you want that in miles, it is about 1,408,812,570,683,452.14, based on 1 Ly = 5,878,625,373,183.61 miles.

In 2007, Hipparcos data was revised with a new parallax of 12.29000 which put Mu2 Gruis at a distance of 265.39 light years or 81.37 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.

Using the 2007 distance, the star is roughly 16,783,650.33 Astronomical Units from the Earth/Sun give or take a few. An Astronomical Unit is the distance between Earth and the Sun. The number of A.U. is the number of times that the star is from the Earth compared to the Sun. The star's Galacto-Centric Distance is 7,354.00 Parsecs or 23,986.05 Light Years. The Galacto-Centric Distance is the distance from the star to the Centre of the Galaxy which is Sagittarius A*.

Travel Time to Mu2 Gruis

The time it will take to travel to this star is dependent on how fast you are going. U.G. has done some calculations as to how long it will take going at differing speeds. A note about the calculations, when I'm talking about years, I'm talking non-leap years only (365 days).

The New Horizons space probe is the fastest probe that we've sent into space at the time of writing. Its primary mission was to visit Pluto which at the time of launch (2006), Pluto was still a planet.

DescriptionSpeed (m.p.h.)Time (years)
Airbus A380736241,813,786.92
Speed of Sound (Mach 1)767.269231,958,996.35
Concorde (Mach 2)1,534.54115,979,347.02
New Horizons Probe33,0005,393,180.22
Speed of Light670,616,629.00265.39

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.

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Additional Mu2 Gruis Facts and Figures

Visual Facts

Primary / Proper / Traditional NameMu2 Gruis
Alternative NamesMu.02 Gru, HD 211202, HIP 109973, HR 8488
Spectral TypeG8III
Constellation's Main StarNo
Multiple Star SystemYes
Star TypeGiant Star
GalaxyMilky Way
Absolute Magnitude 0.78 / 0.56
Visual / Apparent Magnitude5.11
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)22h 16m 26.57
Declination (Dec.)-41° 37` 37.9
Galactic Latitude-55.25825823 degrees
Galactic Longitude358.11421060 degrees
1997 Distance from Earth13.61000 Parallax (milliarcseconds)
 239.65 Light Years
 73.48 Parsecs
2007 Distance from Earth12.29000 Parallax (milliarcseconds)
 265.39 Light Years
 81.37 Parsecs
 16,783,650.33 Astronomical Units
Galacto-Centric Distance23,986.05 Light Years / 7,354.00 Parsecs
Proper Motion Dec.-6.72000 ± 0.51000 milliarcseconds/year
Proper Motion RA.-12.57000 ± 0.64000 milliarcseconds/year
B-V Index0.93
Radial Velocity12.50000 ± 0.80 km/s
Semi-Major Axis8404.0000000
Stellar Luminosity (Lsun)67.8100000
Associated / Clustered StarsMu1 Gruis

Companions (Multi-Star and Exoplanets) Facts

Exoplanet CountNone/Unaware

Estimated Calculated Facts

Radius (x the Sun)9.66
Effective Temperature4,989 Kelvin

Sources and Links

SIMBAD SourceLink

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