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Derakrab Borealis, Upsilon Librae, 39 Librae, HD139063, HIP76470, HR5794

Derakrab Borealis (Upsilon Librae) is a orange to red star that can be located in the constellation of Libra. The star can be seen with the naked eye, that is, you don't need a telescope/binoculars to see it.

Upsilon Librae is the Bayer Classification for the star. The Id of the star in the Yale Bright Star Catalogue is HR5794. HIP76470 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD139063.

Location of Derakrab Borealis

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 Derakrab Borealis, the location is 15h 37m 01.46 and -28d 08` 06.3 .

Proper Motion of Derakrab Borealis

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 -4.15 ± 0.10 miliarcseconds/year towards the north and -12.82 ± 0.19 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 -24.90000 km/s with an error of about 0.70 km/s .

Derakrab Borealis 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 58.0000000 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 Derakrab Borealis

Derakrab Borealis has a spectral type of K3III. This means the star is a orange to red star. The star is 7340.00000000 Parsecs from the Galactic Centre or terms of Light Years is 23940.3894496000000000s. The star has a B-V Colour Index of 1.36 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 4,224 Kelvin.

Derakrab Borealis Radius has been calculated as being 19.84 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 13,802,023.42.km. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 22.78. 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 -0.09 with an error value of 0.06 Fe/H with the Sun has a value of 1 to put it into context.

Derakrab Borealis Apparent and Absolute Magnitudes

Derakrab Borealis has an apparent magnitude of 3.60 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 -0.28 If you used the 2007 Parallax value, you would get an absolute magnitude of -0.58. 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 Derakrab Borealis

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 16.76 which gave the calculated distance to Derakrab Borealis as 194.61 light years away from Earth or 59.67 parsecs. It would take a spaceship travelling at the speed of light, 194.61 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 14.58 which put Derakrab Borealis at a distance of 223.71 light years or 68.59 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 7,340.00 Parsecs or 23,940.39 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.

Derakrab Borealis Facts

Alternative Names

Traditional/Proper NameDerakrab Borealis
Flamsteed Name39 Librae
Flamsteed Short Name39 Lib
Bayer DesignationUpsilon Librae
Hipparcos Library I.D.76470
Yale Bright Star Catalogue (HR) Id5794
Henry Draper Designation139063

Visual Facts

Star Type star
Absolute Magnitude-0.28 / -0.58
Visual / Apparent Magnitude3.60
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)15h 37m 01.46
Declination (Dec.)-28d 08` 06.3
Galactic Latitude21.95 degrees
Galactic Longitude341.88 degrees
1997 Distance from Earth16.76 Parallax (milliarcseconds)
 194.61 Light Years
 59.67 Parsecs
2007 Revised Distance from Earth14.58 Parallax (milliarcseconds)
 223.71 Light Years
 68.59 Parsecs
Galacto-Centric Distance23,940.39 Light Years / 7,340.00 Parsecs
Proper Motion Dec.-4.15 ± 0.10 milliarcseconds/year
Proper Motion RA.-12.82 ± 0.19 milliarcseconds/year
B-V Index1.36
Radial Velocity-24.90 ± 0.70 km/s
Iron Abundance-0.09 ± 0.06 Fe/H
Spectral TypeK3III
Colour(K) Orange to Red

Estimated Facts

Luminosity (x the Sun)58.0000000
Calculated Effective Temperature4,224 Kelvin

Sources and Links

SIMBAD SourceLink

Related Stars

Multi-Star System

The star has been identified as being a multi-star system, one in which there is at least one star in close orbit to another star or two or more stars orbiting a central point. The stars may be of equal mass, unequal mass where one star is stronger than the other or be in groups orbiting a central point which doesn't necessarily have to be a star. More information can be found on my dedicated multiple star systems page. The source of the info is Simbad. The file is dated 2000 so any differences between this and any other source will be down to the actual source from where the information came from.

Proper Motion mas/yr
H.D. IdB.D. IdStar CodeMagnitudeR.A.Dec.SpectrumColourYear

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