Alphecca is the bright jewel of the Northern Crown, a white star with a faint companion that passes in front of it, dimming it slightly at each orbit.
At a glance
| type | white star (class A) |
|---|---|
| distance from the Sun | 75 light-years (23 pc) |
| its light left it | 75 years ago |
| luminosity | 75.6 × the Sun |
| radius | 3.08 × the Sun |
| surface temperature | 9,700 K |
| constellation | Corona Borealis (Northern Crown) |
Read off the piece’s own catalogue, the same values it draws with.
About Alphecca
Alphecca is a white star of class A, wider than the Sun and far more luminous. It is an eclipsing binary: a smaller, fainter star circles it in an orbit we see nearly edge-on, and each time one passes in front of the other the combined light dips by a small amount.
Its name comes from the Arabic for the bright one of the broken ring, the crown’s open circle. It is also known as Gemma, the jewel, for its place in the semicircle of the Northern Crown.
What you see in the piece
In the piece Alphecca is the bright white gem of the crown. Fly out and the semicircle bends apart, because its stars lie at different distances from the Sun.
Questions
Why does Alphecca change brightness?
A fainter companion passes in front of it and behind it on each orbit, so the total light dips slightly. Alphecca is 75 light-years (23 pc) from the Sun.