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Corona Borealis


English name:
Northern Crown
see Stellar data



This small constellation is located between Boötes and Hercules (+40 dec. to +26 dec.; the thought line of 16 RA crosses the 'crown' at its eastern extension). The constellations brightest star Gemma, also known as Alphecca, is set like a juwel in the midst of the crown.

Stars and other objects

The recurrent nova T CrB, also known as the Blaze Star, is with a brightness of 10 mag usually not visible by the eye, but twice it became bright enough to be seen without optical help: First reported in 1866, it reaches 2 mag; in 1946 it brightened again an reached 3 mag. At any time there might be further eruptions.
Within a few years R CrB show enourmous changes in its brightness. Normally its about 6 mag and therefore at the limit where stars can be seen by the naked eye (of course not in the lightpolluted cities), but the brightness can drop down to 14 mag within a few weeks. When this is going to take place is not predictable. After that drastic drop in brightness it can take months before the normal Magnitude is reached again. A possible explanation is that carbon particles at the outer layers of the star are more or less periodically (chaotic ?) are build up and then blown away darkening the radiation of the star.
Gamma CrB and eta CrB are close doubles, the first requiring about 101 years, the latter 42 years for a revolution.
For small scopes zeta CrB is a nice pair of blue stars (5 mag and 6 mag) to observe.
Nu1 nu2 CrB is a wide pair of 5 mag orange giants, best seen in binoculars. This pair is not physically related.

Mythological Background

In his "Metamorphoses", book VIII, the roman poet Ovid (Publius Ovidius Naso, 43 BC to 17 AC) mentions the story of Theseus and the Minotaurus and how Theseus was able to overcome that monster with the help of the princess of Crete, Ariadne. Leaded by the string she gave Theseus he was able to escape the dark caves of the labyrinth where the Minotaurus had lived.
After this success he took Ariadne with him to Naxos. But once they reached the coast Theseus left her. Her cries and lamentations were heard by Bacchus, who gave her his love and protection. To make glorify her forever between the stars he took her crown and lift it up to the skies. During its flight the juwels turned to glittering stars still forming a crown.

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C. Kronberg --- 96/10/23 --- smil at clell.de