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AF Coronae Borealis

AF Coronae Borealis Facts

  • AF Coronae Borealis is a variable star that can be located in the constellation of Corona Borealis. The description is based on the spectral class.
  • AF Coronae Borealis is not part of the constellation outline but is within the borders of the constellation.
  • Based on the spectral type (K2) of the star, the star's colour is orange to red .
  • The star can not be seen by the naked eye, you need a telescope to see it.
  • Using the most recent figures given by the 2007 Hipparcos data, the star is 1101.90 light years away from us. Distance

AF Coronae Borealis's Alternative Names

HIP79162 is the reference name for the star in the Hipparcos Star Catalogue.

AF Coronae Borealis has alternative name(s) :- , AF 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+31 2820.

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

Location of AF Coronae Borealis

The location of the variable 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 object is compared to the celestial equator and is expressed in degrees. For AF Coronae Borealis, the location is 16h 09m 24.80 and +30° 52` 00.9 .

Proper Motion of AF 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 8.10 ± 1.05 milliarcseconds/year towards the north and -31.32 ± 1.49 milliarcseconds/year east if we saw them in the horizon. . When the value is negative then the star and the Sun are getting closer to one another, likewise, a positive number means that two stars are moving away. Its nothing to fear as the stars are so far apart, they won't collide in our life-time, if ever.

Physical Properties of AF Coronae Borealis

AF Coronae Borealis Colour and Temperature

Based on the star's spectral type of K2 , AF Coronae Borealis's colour and type is orange to red variable star. The star has a B-V Colour Index of 1.36 which means the star's temperature is about 4,280 Kelvin. The temperature was calculated using information from Morgans @ Uni.edu.

AF Coronae Borealis Radius

AF Coronae Borealis estimated radius has been calculated as being 6.49 times bigger than the Sun. The Sun's radius is 695,800km, therefore the star's radius is an estimated 4,513,150.06.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 6.8233308371928649456065769353. The figure is derived at by using the formula from SDSS rather than peer reviewed papers. It has been known to produce widely incorrect figures.

AF Coronae Borealis Apparent and Absolute Magnitudes

AF Coronae Borealis has an apparent magnitude of 9.62 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 2.09 If you used the 2007 Parallax value, you would get an absolute magnitude of 1.98. 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 AF Coronae Borealis

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 3.12000 which gave the calculated distance to AF Coronae Borealis as 1045.40 light years away from Earth or 320.51 parsecs. If you want that in miles, it is about 6,145,514,965,126,145.89, based on 1 Ly = 5,878,625,373,183.61 miles.

In 2007, Hipparcos data was revised with a new parallax of 2.96000 which put AF Coronae Borealis at a distance of 1101.90 light years or 337.84 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.

Using the 2007 distance, the star is roughly 69,684,016.58 Astronomical Units from the Earth/Sun give or take a few. An Astronomical Unit is the distance between Earth and the Sun. The number of A.U. is the number of times that the star is from the Earth compared to the Sun.

Travel Time to AF Coronae Borealis

The time it will take to travel to this star is dependent on how fast you are going. U.G. has done some calculations as to how long it will take going at differing speeds. A note about the calculations, when I'm talking about years, I'm talking non-leap years only (365 days).

The New Horizons space probe is the fastest probe that we've sent into space at the time of writing. Its primary mission was to visit Pluto which at the time of launch (2006), Pluto was still a planet.

DescriptionSpeed (m.p.h.)Time (years)
Walking4184,738,115,873.78
Car1206,157,937,195.79
Airbus A3807361,004,011,499.31
Speed of Sound (Mach 1)767.269963,094,382.15
Concorde (Mach 2)1,534.54481,546,563.46
New Horizons Probe33,00022,392,498.89
Speed of Light670,616,629.001,101.90
AF Coronae Borealis brightness ranges from a magnitude of 9.827 to a magnitude of 9.717 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 1.5 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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Additional AF Coronae Borealis Facts and Figures

Visual Facts


Primary / Proper / Traditional NameAF Coronae Borealis
Alternative NamesHIP 79162, BD+31 2820, AF CrB
Spectral TypeK2
Constellation's Main StarNo
Multiple Star SystemNo / Unknown
Star TypeVariable Star
ColourOrange to Red
GalaxyMilky Way
ConstellationCorona Borealis
Absolute Magnitude 2.09 / 1.98
Visual / Apparent Magnitude9.62
Naked Eye VisibleRequires a 7x50 Binoculars - Magnitudes
Right Ascension (R.A.)16h 09m 24.80
Declination (Dec.)+30° 52` 00.9
Galactic Latitude46.89784183 degrees
Galactic Longitude50.16014995 degrees
1997 Distance from Earth3.12000 Parallax (milliarcseconds)
 1045.40 Light Years
 320.51 Parsecs
2007 Distance from Earth2.96000 Parallax (milliarcseconds)
 1101.90 Light Years
 337.84 Parsecs
 69,684,016.58 Astronomical Units
Proper Motion Dec.8.10000 ± 1.05000 milliarcseconds/year
Proper Motion RA.-31.32000 ± 1.49000 milliarcseconds/year
B-V Index1.36

Companions (Multi-Star and Exoplanets) Facts


Exoplanet CountNone/Unaware

Variable Star Details


Mean Variability Period in Days1.516
Variable Magnitude Range (Brighter - Dimmer)9.717 - 9.827

Estimated Calculated Facts


Radius (x the Sun)6.82
Effective Temperature4,280 Kelvin

Sources and Links


SIMBAD SourceLink

Related Stars


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