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Zubeneschamali, Beta Librae, 27 Librae, HD135742, HIP74785, HR5685

Zubeneschamali (Beta Librae) is a blue main sequence dwarf star that can be located in the constellation of Libra. Zubeneschamali is the 1st brightest star in Libra 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.

Beta Librae is the Bayer Classification for the star. The Id of the star in the Yale Bright Star Catalogue is HR5685. HIP74785 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD135742.

Zubeneschamali has alternative name(s), 27 Librae, Lanx Australis , . In Arabic, it is known as Az-Zuban ash-Shamali.

Zubeneschamali is a star that creates a lot of discussion. There are a number of people who state this star is green and not any of the uniform star colours such as Blue, Yellow or White. Those who disagree about the colour say it is an optical illusion caused by the its environment. It is not the only star that is believed to be green, the companion star of Antares is also believed to be green but Zubenschamali is the brightest star that is possibly green.

The question over its colour maybe answered when the James Webb telescope goes into operation and takes a close look at the star. Failing that we`ll either have to visit it or wait for another advanced telescope to put up into space to take a look at the star.

Location of Zubeneschamali

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 Zubeneschamali, the location is 15h 17m 00.47 and -09d 22` 58.3 .

Proper Motion of Zubeneschamali

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 -19.65 ± 0.10 miliarcseconds/year towards the north and -98.10 ± 0.16 miliarcseconds/year east if we saw them in the horizon.

Zubeneschamali 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 73.0000000 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 Zubeneschamali

Zubeneschamali has a spectral type of B8V. This means the star is a blue main sequence dwarf star. The star is 7357.00000000 Parsecs from the Galactic Centre or terms of Light Years is 23995.8372180800000000s. The star has a B-V Colour Index of -0.07 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 10,845 Kelvin.

Zubeneschamali Radius has been calculated as being 3.89 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 2,709,798.29.km. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 4.51. 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 0.33 with an error value of 9.99 Fe/H with the Sun has a value of 1 to put it into context.

Zubeneschamali Apparent and Absolute Magnitudes

Zubeneschamali has an apparent magnitude of 2.61 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 -0.84 If you used the 2007 Parallax value, you would get an absolute magnitude of -1.16. 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 Zubeneschamali

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 20.38 which gave the calculated distance to Zubeneschamali as 160.04 light years away from Earth or 49.07 parsecs. It would take a spaceship travelling at the speed of light, 160.04 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 17.62 which put Zubeneschamali at a distance of 185.11 light years or 56.75 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 7,357.00 Parsecs or 23,995.84 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.

Zubeneschamali Facts

Alternative Names

Traditional/Proper NameZubeneschamali
Arabic NameAz-Zuban ash-Shamali
English MeaningThe northern claw
Bayer DesignationBeta Librae
Alternative Name(s)27 Librae, Lanx Australis
Hipparcos Library I.D.74785
Yale Bright Star Catalogue (HR) Id5685
Bonner DurchmusterungBD-08 3935
Henry Draper Designation135742

Visual Facts

Star Typemain sequence dwarf star
Absolute Magnitude-0.84 / -1.16
Visual / Apparent Magnitude2.61
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)15h 17m 00.47
Declination (Dec.)-09d 22` 58.3
Galactic Latitude39.23 degrees
Galactic Longitude352.02 degrees
1997 Distance from Earth20.38 Parallax (milliarcseconds)
 160.04 Light Years
 49.07 Parsecs
2007 Revised Distance from Earth17.62 Parallax (milliarcseconds)
 185.11 Light Years
 56.75 Parsecs
Galacto-Centric Distance23,995.84 Light Years / 7,357.00 Parsecs
Proper Motion Dec.-19.65 ± 0.10 milliarcseconds/year
Proper Motion RA.-98.10 ± 0.16 milliarcseconds/year
B-V Index-0.07
Radial Velocity-35.60 ± 1.80 km/s
Iron Abundance0.33 ± 9.99 Fe/H
Spectral TypeB8V
Colour(B) blue

Estimated Facts

Luminosity (x the Sun)73.0000000
Calculated Effective Temperature10,845 Kelvin

Sources and Links

SIMBAD SourceLink

Related Stars

Location of Zubeneschamali in Libra

Zubeneschamali (Beta Librae) Location in Libra

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

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