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Minchir (Sigma Hydrae) - HD73471 - HIP42402

Minchir (Sigma Hydrae) is a orange to red giant star that can be located in the constellation of Hydra. Sigma Hydrae is the Bayer Classification for the star. HIP42402 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD73471. The Id of the star in the Gould Star Catalogue is 42. 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. Minchir has alternative name(s), 5 Hydrae , 5 Hya.

Location of Minchir

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 Minchir, the location is 08h 38m 45.45 and +03d20`29.3 .

Proper Motion of Minchir

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 -15.92 ± 0.13 miliarcseconds/year towards the north and -19.48 ± 0.25 miliarcseconds/year east if we saw them in the horizon.

Minchir 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 70.0000000 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 Minchir

Minchir has a spectral type of K2III. This means the star is a orange to red giant star. The star has a B-V Colour Index of 1.21 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 4,472 Kelvin.

Minchir has been calculated as 21.67 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 15,079,651.65.km.

Minchir Apparent and Absolute Magnitudes

Minchir has an apparent magnitude of 4.45 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 -0.72 If you used the 2007 Parallax value, you would get an absolute magnitude of -0.84. 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 Minchir

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 9.25 which gave the calculated distance to Minchir as 352.61 light years away from Earth or 108.11 parsecs. It would take a spaceship travelling at the speed of light, 352.61 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 8.75 which put Minchir at a distance of 372.76 light years or 114.29 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.

Meteor Showers Radiating from near Minchir

The Sigma Hydrids Meteor Shower radiants from a point near this star. The meteor shower runs typically between Dec 03 - Dec 15 with a peak date of Dec 12. The speed of a meteor in the shower is 59 Km/s. The amount of meteors predicted to be seen per hour (Zenith Hourly Rate) is 59.

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.

Minchir Facts

Alternative Names

Traditional/Proper NameMinchir
Short Name5 Hya
Bayer DesignationSigma Hydrae
Alternative Name(s)5 Hydrae
Hipparcos Library I.D.42402
Bonner DurchmusterungBD+03 2026
Gould I.D.42
Henry Draper Designation73471

Visual Facts

Star Typegiant star
Absolute Magnitude-0.72 / -0.84
Apparent Magnitude4.45
Right Ascension (R.A.)08h 38m 45.45
Declination (Dec.)+03d20`29.3
1997 Distance from Earth9.25 Parallax (milliarcseconds)
 352.61 Light Years
 108.11 Parsecs
2007 Revised Distance from Earth8.75 Parallax (milliarcseconds)
 372.76 Light Years
 114.29 Parsecs
Proper Motion Dec.-15.92 ± 0.13 milliarcseconds/year
Proper Motion RA.-19.48 ± 0.25 milliarcseconds/year
B-V Index1.21
Spectral TypeK2III
Colour(K) Orange to Red

Estimated Facts

Radius (x the Sun)21.67
Luminosity (x the Sun)70.0000000
Calculated Effective Temperature4,472 Kelvin

Sources and Links

SIMBAD SourceLink

Related Stars

Location of Minchir in Hydra


Minchir (Sigma Hydrae) Location in Hydra

The map was generated using Night Vision, an awesome free application by Brian Simpson.


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