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Mu Hydri, HD16522, HIP11757, HR776

Mu Hydri is a white to yellow giant star that can be located in the constellation of Hydrus. Mu Hydri is the brightest star in Hydrus 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.

Mu Hydri is the Bayer Classification for the star. The Id of the star in the Yale Bright Star Catalogue is HR776. HIP11757 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD16522.

Location of Mu Hydri

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 Mu Hydri, the location is 02h 31m 40.12 and -79d 06` 33.3 .

Proper Motion of Mu Hydri

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 -54.22 ± 0.32 miliarcseconds/year towards the north and 137.24 ± 0.34 miliarcseconds/year east if we saw them in the horizon. The Radial Velocity, that is the speed at which the star is moving away/towards us is -14.50000 km/s with an error of about 0.80 km/s .

Physical Properties (Colour, Temperature, Radius) of Mu Hydri

Mu Hydri has a spectral type of G4III. This means the star is a white to yellow giant star. The star is 7369.00000000 Parsecs from the Galactic Centre or terms of Light Years is 24034.9768193600000000s. The star has a B-V Colour Index of 0.98 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 4,888 Kelvin.

Mu Hydri Radius has been calculated as being 10.30 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 7,163,420.23.km. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 10.01. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures.

Mu Hydri Apparent and Absolute Magnitudes

Mu Hydri has an apparent magnitude of 5.27 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 0.51 If you used the 2007 Parallax value, you would get an absolute magnitude of 0.57. 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 Mu Hydri

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 11.18 which gave the calculated distance to Mu Hydri as 291.74 light years away from Earth or 89.45 parsecs. It would take a spaceship travelling at the speed of light, 291.74 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 11.49 which put Mu Hydri at a distance of 283.87 light years or 87.03 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 7,369.00 Parsecs or 24,034.98 Light Years. The Galacto-Centric Distance is the distance from the star to the Centre of the Galaxy which is Sagittarius A*.

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.

Mu Hydri Facts

Alternative Names

Bayer DesignationMu Hydri
Hipparcos Library I.D.11757
Yale Bright Star Catalogue (HR) Id776
Henry Draper Designation16522

Visual Facts

Star Typegiant star
Absolute Magnitude0.51 / 0.57
Visual / Apparent Magnitude5.27
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)02h 31m 40.12
Declination (Dec.)-79d 06` 33.3
Galactic Latitude-36.88 degrees
Galactic Longitude297.19 degrees
1997 Distance from Earth11.18 Parallax (milliarcseconds)
 291.74 Light Years
 89.45 Parsecs
2007 Revised Distance from Earth11.49 Parallax (milliarcseconds)
 283.87 Light Years
 87.03 Parsecs
Galacto-Centric Distance24,034.98 Light Years / 7,369.00 Parsecs
Proper Motion Dec.-54.22 ± 0.32 milliarcseconds/year
Proper Motion RA.137.24 ± 0.34 milliarcseconds/year
B-V Index0.98
Radial Velocity-14.50 ± 0.80 km/s
Spectral TypeG4III
Colour(G) White to Yellow

Estimated Facts

Calculated Effective Temperature4,888 Kelvin

Sources and Links

SIMBAD SourceLink

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