Corona Borealis, the Northern Crown, is a small, perfect semicircle of stars between Boötes and Hercules, its brightest jewel the white star Alphecca.
At a glance
| stars in the figure | 7 |
|---|---|
| nearest star of the figure | Alphecca, 75 light-years (23 pc) |
| farthest star of the figure | Theta Coronae Borealis, 375 light-years (115 pc) |
| depth | the farthest is 5 × farther than the nearest |
Read off the piece’s own catalogue, the same values it draws with.
About Corona Borealis
Corona Borealis is an ancient Greek constellation, the crown of Ariadne set in the sky by Dionysus. Its stars form a neat, open arc, with Alphecca, also called Gemma, the gem at its centre. Nusakan is another of its stars. Small as it is, the crown is easy to recognise once found, between Arcturus and the Keystone of Hercules.
The constellation holds two famous variable stars. T Coronae Borealis is a recurrent nova, normally far too faint to see, that flares up to naked-eye brightness at long intervals. R Coronae Borealis does the opposite: it is usually visible in binoculars but now and then vanishes as clouds of soot form around it. The crown is best seen on northern spring and summer evenings.
What you see in the piece
Flown out to, the arc of the crown breaks: Alphecca, its jewel, is the nearest star of the figure, while Theta Coronae Borealis lies several times deeper.
Questions
What is T Coronae Borealis?
A recurrent nova in the Northern Crown: a white dwarf drawing gas from a red giant companion, which periodically ignites in an outburst bright enough to see with the naked eye.
How far away are the stars of Corona Borealis?
They range from Alphecca, 75 light-years (23 pc), to Theta Coronae Borealis, 375 light-years (115 pc): the farthest is 5 × farther than the nearest.