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YY Coronae Borealis, HD141990, HIP77598

YY Coronae Borealis is a white to yellow eclipsing binary system variable star that can be located in the constellation of Corona Borealis. The description is based on the spectral class. The star can not be seen by the naked eye, you need a telescope to see it. The star has an estimated age of 6.30 Billion of Years but could be as young as 5.40 to 7.20 according to Hipparcos.

YY Coronae Borealis's Alternative Names

HIP77598 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD141990.

YY Coronae Borealis has alternative name(s) :- , YY CrB.

BD number is the number that the star was filed under in the Durchmusterung or Bonner Durchmusterung, a star catalogue that was put together by the Bonn Observatory between 1859 to 1903. The star's BD Number is BD+38 2706.

More details on star alternative names can be found at Star Names .

Location of YY Coronae Borealis

The location of the star in the night sky 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 YY Coronae Borealis, the location is 15h 50m 32.49 and +37° 50` 07.5 .

Proper Motion of YY 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 11.29 ± 0.68 miliarcseconds/year towards the north and -73.76 ± 0.82 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 -4.58000 km/s with an error of about 1.02 km/s .

YY 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 2.57 that I have given is based on the value in the Simbad Hipparcos Extended Catalogue at the University of Strasbourg from 2012.

Physical Properties (Colour, Temperature, Age) of YY Coronae Borealis

YY Coronae Borealis has a spectral type of G5. This means the star is a white to yellow variable star. The star is 7,372.00 Parsecs from the Galactic Centre or terms of Light Years is 24,044.76 s. The star has a B-V Colour Index of 0.62 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 5,829 Kelvin.

YY Coronae Borealis Radius has been calculated as being 1.47 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 1,023,671.81.km. If you need the diameter of the star, you just need to multiple the radius by 2. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 1.55. 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 -0.11 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 6.30 Billion years old but could be between 5.40 and 7.20 Billion years old. In comparison, the Sun's age is about 4.6 Billion Years Old.

YY Coronae Borealis Apparent and Absolute Magnitudes

YY Coronae Borealis has an apparent magnitude of 8.69 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 3.97 If you used the 2007 Parallax value, you would get an absolute magnitude of 3.86. 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 YY Coronae Borealis

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 11.36 which gave the calculated distance to YY Coronae Borealis as 287.12 light years away from Earth or 88.03 parsecs. It would take a spaceship travelling at the speed of light, 287.12 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 10.83 which put YY Coronae Borealis at a distance of 301.17 light years or 92.34 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 7,372.00 Parsecs or 24,044.76 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 YY Coronae Borealis

The star is a eclipsing binary system W Ursae Majoris 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. YY Coronae Borealis brightness ranges from a magnitude of 9.134 to a magnitude of 8.643 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 0.4 days (variability).

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.

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YY Coronae Borealis Facts

Visual Facts


Primary / Proper / Traditional NameYY Coronae Borealis
Alternative NamesHD 141990, HIP 77598, BD+38 2706, YY CrB
Spectral TypeG5
Multiple Star SystemNo / Unknown
Star TypeVariable Star
Colour white to yellow
GalaxyMilky Way
ConstellationCorona Borealis
Age6.30 Billion Years Old
Age Range5.40 - 7.20 Billion Years Old
Absolute Magnitude3.97 / 3.86
Visual / Apparent Magnitude8.69
Naked Eye VisibleRequires a 7x50 Binoculars - Magnitudes
Right Ascension (R.A.)15h 50m 32.49
Declination (Dec.)+37° 50` 07.5
Galactic Latitude51.14 degrees
Galactic Longitude60.49 degrees
1997 Distance from Earth11.36 Parallax (milliarcseconds)
 287.12 Light Years
 88.03 Parsecs
2007 Distance from Earth10.83 Parallax (milliarcseconds)
 301.17 Light Years
 92.34 Parsecs
Galacto-Centric Distance24,044.76 Light Years / 7,372.00 Parsecs
Proper Motion Dec.11.29 ± 0.68 milliarcseconds/year
Proper Motion RA.-73.76 ± 0.82 milliarcseconds/year
B-V Index0.62
Radial Velocity-4.58 ± 1.02 km/s
Iron Abundance-0.11 ± 9.99 Fe/H
Eccentricity0.06
Semi-Major Axis7001.00
Stellar Luminosity (Lsun)2.57

Companions (Multi-Star and Exoplanets) Facts


Exoplanet CountNone/Unaware

Variable Star Details


Variable Star ClassEclipsing binary system
Variable Star TypeW Ursae Majoris
Mean Variability Period in Days0.377
Variable Magnitude Range (Brighter - Dimmer)8.643 - 9.134

Estimated Facts


Calculated Effective Temperature5,829 Kelvin

Sources and Links


SIMBAD SourceLink

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