Universe Guide

HomeFactsConstellationsCorona Borealis

Sigma Coronae Borealis - HD146361 - HIP79607

Sigma Coronae Borealis is a blue to white eclipsing binary system main sequence dwarf star that can be located in the constellation of CoronaBorealis. The star can be seen with the naked eye, that is, you don't need a telescope/binoculars to see it. The star has an estimated age of 7.10 Billion of Years but could be as young as 6.60 to 7.70 according to Hipparcos.

Sigma Coronae Borealis is the Bayer Classification for the star. HIP79607 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD146361. The Gliese ID of the star is Gliese GL615.2A. The star was part of the original catalogue devised by German Astronomer Wilheim Gliese of stars located within 20 parsecs of Earth. Ref : Star Names.

Sigma Coronae Borealis has alternative name(s), 17 Coronae Borealis , TZ_CrB, 17 CrB. Sigma Coronae Borealis is a multiple star system with 2 stars orbiting in its solar system.

Location of Sigma Coronae 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 Sigma Coronae Borealis, the location is 16h 14m 41.04 and +33d51`31.8 .

Proper Motion of Sigma Coronae 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 -92.67 ± 1.09 miliarcseconds/year towards the north and -263.39 ± 1.22 miliarcseconds/year east if we saw them in the horizon.

Sigma Coronae 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 1.0000000 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, Age, Radius) of Sigma Coronae Borealis

Sigma Coronae Borealis has a spectral type of F8V. This means the star is a blue to white main sequence dwarf star. The star is 7391.00000000 Parsecs from the Galactic Centre or terms of Light Years is 24106.7327550400000000s. The star has a B-V Colour Index of 0.59 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 5,931 Kelvin.

Sigma Coronae Borealis Radius has been calculated as being 1.72 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 1,199,767.60.km. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 1.68. 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 -0.17 with an error value of 9.99 Fe/H with the Sun has a value of 1 to put it into context.

The stars age according to Hipparcos data files put the star at an age of about 7.10 Billion years old but could be between 6.60 and 7.70 Billion years old. In comparison, the Sun's age is about 4.6 Billion Years Old.

Sigma Coronae Borealis Apparent and Absolute Magnitudes

Sigma Coronae Borealis has an apparent magnitude of 5.23 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 3.55 If you used the 2007 Parallax value, you would get an absolute magnitude of 3.61. 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 Sigma Coronae Borealis

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 46.11 which gave the calculated distance to Sigma Coronae Borealis as 70.74 light years away from Earth or 21.69 parsecs. It would take a spaceship travelling at the speed of light, 70.74 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 47.44 which put Sigma Coronae Borealis at a distance of 68.75 light years or 21.08 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 7,391.00 Parsecs or 24,106.73 Light Years. The Galacto-Centric Distance is the distance from the star to the Centre of the Galaxy which is Sagittarius A*.

Variable Type of Sigma Coronae Borealis

The star is a eclipsing binary system RS Canum Venaticorum variable type which means that its size changes over time. The Variable Type is usually named after the first star of that type to be spotted. Sigma Coronae Borealis brightness ranges from a magnitude of 6.000 to a magnitude of 5.000 over its variable period. The smaller the magnitude, the brighter the star.

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.

Sigma Coronae Borealis Facts

Alternative Names

Short NameTZ CrB, 17 CrB
Bayer DesignationSigma Coronae Borealis
Alternative Name(s)17 Coronae Borealis
Hipparcos Library I.D.79607
Bonner DurchmusterungBDD+34 2750
Gliese ID615.2A
Henry Draper Designation146361

Visual Facts

Star Typemain sequence dwarf star
Age7.10 Billion Years Old
Age Range6.60 - 7.70 Billion Years Old
Absolute Magnitude3.55 / 3.61
Visual / Apparent Magnitude5.23
Naked Eye VisibleYes - Ref: Wiki
Right Ascension (R.A.)16h 14m 41.04
Declination (Dec.)+33d51`31.8
Galactic Latitude46.14 degrees
Galactic Longitude54.67 degrees
1997 Distance from Earth46.11 Parallax (milliarcseconds)
 70.74 Light Years
 21.69 Parsecs
2007 Revised Distance from Earth47.44 Parallax (milliarcseconds)
 68.75 Light Years
 21.08 Parsecs
Galacto-Centric Distance24,106.73 Light Years / 7,391.00 Parsecs
Proper Motion Dec.-92.67 ± 1.09 milliarcseconds/year
Proper Motion RA.-263.39 ± 1.22 milliarcseconds/year
B-V Index0.59
Radial Velocity-12.30 ± 0.06 km/s
Iron Abundance-0.17 ± 9.99 Fe/H
Spectral TypeF8V
Colour(F) blue to white
Stars in Solar System2

Variable Star Details

Variable Star ClassEclipsing binary system
Variable Star TypeRS Canum Venaticorum
Variable Magnitude Range (Brighter - Dimmer)5.000 - 6.000

Estimated Facts

Luminosity (x the Sun)1.0000000
Calculated Effective Temperature5,931 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
146361+34 2750.0A5.80000-277.00000-85.00000G0Yellow
146362B6.70000G0Yellow1827
C13.30000-16.00000-15.000001935
D10.800002.00000-21.000001933

Add a Comment


Name:
Email: (Optional)
Comment: