Corona borealis

Corona Borealis has endured to become a part of the 88 modern constellations recognized by the International Astronomical Union. Then known only as ‘Corona’, it was one of the original 48 constellations crafted by Ptolemy. It is the counterpart to Corona Australis and is also known as the ‘the Northern Crown’. It is a small, faint constellation visible in the month of July. A constellation of the Ursa Major group, it has no bright stars, 6 main stars and 24 stellar members with Bayer/ Flamsteed designations. Let us discuss this constellation in detail.

Which stars comprise the constellation?

Some of the stars of Corona Borealis include:

  • Alphecca (Gemma) a Coronae Borealis (Alpha Coronae Borealis): It is the brightest of all its seven stars which make up the Ariadne’s crown. Alphecca is basically an eclipsing star with a period of 17.36 days. Its magnitude varies between 2.21 and 2.32. Its primary component is a white main sequence star which emits an excess of infrared radiation. Alphecca is about 75 light years away.
  • Nusakan (Beta Coronae Borealis): Nusakan is a spectroscopic binary with a period of about 10.5 years. It is the second brightest star in Corona Borealis and is about 114 light years away from the solar system. Its traditional name, Nusakan, is originated from the Arabic word nasaqan which means ‘the (two) series’.
  • Y Coronae Borealis (Gamma Coronae Borealis): It is basically a binary star with an orbit period of 91 years. It is usually classified as Delta Scuti variable as it portrays variations in its luminosity due to both radial and non–radial pulsations of its surface. Its magnitude varies between 3.80 and 3.86.
  • ζ Coronae Borealis (Zeta Coronae Borealis): Zeta Coronae Borealis is a double star in this constellation. It basically comprises of a pair of blue and white stars. It is about 220 light years away from the solar system.
  • T Coronae Borealis (Blaze Star): In Corona Borealis, T Coronae Borealis is a recurrent nova, often termed as the Blaze Star. It usually has a magnitude of about 10–10.8. It is a red giant, about 2,000 light years away.
  • ρ Coronae Borealis (Rho Coronae Borealis): It is a yellow dwarf star in this constellation with a magnitude of about 5.4. It is considered as a solar twin, with about the same mass, radius and luminosity as the Sun. In the year 1997, a planet was discovered in the star’s orbit. It is about 56.2 light years away.
  • R Coronae Borealis – (Fade-Out Star): R Coronae Borealis is a yellow supergiant star in this constellation. It has a magnitude of 6.46 and is about 6,000 light years away. It is a variable star as its brightness fades by several magnitudes at irregular intervals. Its variability is the result of the cloud of carbon dust which is created in the line of sight which dims its visual magnitude of several magnitudes. When the cloud of dust moves away, it becomes brighter again. Due to such dramatic changes, it is termed as Fade–Out Star.
  • k Coronae Borealis (Kappa Coronae Borealis): It is an orange super giant with a visual magnitude of 4.82 and is about 101.5 light years away from the earth. In the year 2007, a giant planet was discovered in the star’s orbit.
  • HD 144579: In this constellation, HD 144579 is the closest star to the solar system. It is basically a binary star and is about 13.91 light years away from the earth. It comprises of a primary component, which has a visual magnitude of 5.87.

Some of the other notable stars of this constellation are Eta Coronae Borealis, Sigma Coronae Borealis, Delta Coronae Borealis and Nu Coronae Borealis

Does it contain any deep sky objects or galaxies?

Corona Borealis Galaxy Cluster (Abell 2065) is the only deep sky object in this constellation and is basically a densely populated galaxy cluster in this Constellation. It is about 1 to 1.5 billion light years away. Abell 2065 comprises of more than 400 galaxies in an area spanning around one degree in the sky. The galaxies in this cluster are more than billion light years away. In this cluster, the brightest galaxy has a visual magnitude of 16.5.

What is its position in the galaxy?

Corona Borealis lies in the third quadrant of the northern hemisphere and can be seen at latitudes between +90° and -500.

How much space does it occupy in the sky?

It occupies an area of 179 square degrees, making it the 73rd constellation in size.

What is the cultural or mythological significance of Corona Borealis?

The myth associated with Corona Borealis is of that of Princess Ariadne of Crete. According to the myth, she married the god Dionysus and the circlet of stars in the constellation of Corona Borealis represents the crown by the god Hephaestusthat she wore on her wedding day.

Which are its neighbouring constellations?

Bootes, Hercules and Serpens Caput are its neighbouring constellations.

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