The location of the subgiant 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 CoRoT-21, the location is 06h 44m 12.59 and 00° 17` 56.87 .
CoRoT-21 has a spectral type of F8IV. This means the star is a blue to white subgiant star.
CoRoT-21 has been calculated as 1.95 times bigger than the Sun. The Sun's radius is 695,800km, therefore the star's radius is an estimated 1,353,331.00.km. If you need the diameter of the star, you just need to multiple the radius by 2.
The star's metallicity is 0.100000, this value is the fractional amount of the star that is not Hydrogen (X) or Helium (Y). An older star would have a high metallicity whereas a new star would have a lower one.
The star is believed to be about 4.10 Billion years old. To put in context, the Sun is believed to be about five billion years old and the Universe is about 13.8 billion years old.
CoRoT-21 has an apparent magnitude of 16.00 which is how bright we see the star from Earth. Apparent Magnitude is also known as Visual Magnitude. 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.
|Primary / Proper / Traditional Name||CoRoT-21|
|Constellation's Main Star||No|
|Multiple Star System||No / Unknown|
|Star Type||Subgiant Star|
|Colour||Yellow - White|
|Age||4.10 Billion Years Old|
|Visual / Apparent Magnitude||16.00|
|Naked Eye Visible||Requires 8m Telescope - Magnitudes|
|Right Ascension (R.A.)||06h 44m 12.59|
|Declination (Dec.)||00° 17` 56.87|
|Radius (x the Sun)||1.95|
|Name||Status||Mass (Jupiters)||Orbital Period (Days)||Eccentricity||Discovered||Semi-Major Axis||Periastron||Inclination|
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