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Sargas (Theta Scorpii) - HD159532 - HIP86228 - HR6553

Sargas (Theta Scorpii) is a blue to white luminous giant star that can be located in the constellation of Scorpius. It is the 38th brightest star in the night sky. The star can be seen with the naked eye, that is, you don't need a telescope/binoculars to see it.

Theta Scorpii is the Bayer Classification for the star. The Id of the star in the Yale Bright Star Catalogue is HR6553. HIP86228 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD159532. Sargas is a multiple star system with 2 stars orbiting in its solar system.

Location of Sargas

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 Sargas, the location is 17h 37m 19.13 and -42d59`52.2 .

Proper Motion of Sargas

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 -3.12 ± 1.07 miliarcseconds/year towards the north and 5.54 ± 1.49 miliarcseconds/year east if we saw them in the horizon.

Physical Properties (Colour, Temperature, Radius) of Sargas

Sargas has a spectral type of F1II. This means the star is a blue to white luminous giant star. The star is 7320.00000000 Parsecs from the Galactic Centre or terms of Light Years is 23875.1567808000000000s. The star has a B-V Colour Index of 0.4 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 6,398 Kelvin.

Sargas Radius has been calculated as being 26.97 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 18,764,040.30.km. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 29.71. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures.

Sargas Apparent and Absolute Magnitudes

Sargas has an apparent magnitude of 1.86 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 -2.75 If you used the 2007 Parallax value, you would get an absolute magnitude of -2.96. 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 Sargas

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 11.99 which gave the calculated distance to Sargas as 272.03 light years away from Earth or 83.40 parsecs. It would take a spaceship travelling at the speed of light, 272.03 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 10.86 which put Sargas at a distance of 300.33 light years or 92.08 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 7,320.00 Parsecs or 23,875.16 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.

Sargas Facts

Alternative Names

Traditional/Proper NameSargas
Bayer DesignationTheta Scorpii
Hipparcos Library I.D.86228
Yale Bright Star Catalogue (HR) Id6553
Henry Draper Designation159532

Visual Facts

Star Typeluminous giant star
Absolute Magnitude-2.75 / -2.96
Visual / Apparent Magnitude1.86
Naked Eye VisibleYes - Ref: Wiki
Right Ascension (R.A.)17h 37m 19.13
Declination (Dec.)-42d59`52.2
Galactic Latitude-5.98 degrees
Galactic Longitude347.14 degrees
1997 Distance from Earth11.99 Parallax (milliarcseconds)
 272.03 Light Years
 83.40 Parsecs
2007 Revised Distance from Earth10.86 Parallax (milliarcseconds)
 300.33 Light Years
 92.08 Parsecs
Galacto-Centric Distance23,875.16 Light Years / 7,320.00 Parsecs
Proper Motion Dec.-3.12 ± 1.07 milliarcseconds/year
Proper Motion RA.5.54 ± 1.49 milliarcseconds/year
B-V Index0.40
Radial Velocity1.40 ± 2.50 km/s
Spectral TypeF1II
Brightest in Night Sky38th
Colour(F) blue to white
Stars in Solar System2

Estimated Facts

Calculated Effective Temperature6,398 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
159532-4212312.2A1.9000015.00000-2.00000F0Yellow/White
B1896

Location of Sargas in Scorpius


Sargas (Theta Scorpii) Location in Scorpius

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


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