Alfirk is Beta Cephei, a hot blue-white star that pulsates over a matter of hours and has given its name to a whole class of variable stars.
At a glance
| type | blue-white star (class B) |
|---|---|
| distance from the Sun | 685 light-years (210 pc) |
| its light left it | 685 years ago |
| luminosity | 13,700 × the Sun |
| radius | 8.07 × the Sun |
| surface temperature | 22,000 K |
| constellation | Cepheus (King) |
Read off the piece’s own catalogue, the same values it draws with.
About Alfirk
It is a blue-white star of class B, far hotter than the Sun and vastly more luminous. Its brightness rises and falls slightly as the star swells and shrinks, a pulsation driven deep in its outer layers.
Stars that pulsate this way are now called Beta Cephei variables, after it: massive, hot young stars with short, regular cycles. Its name comes from the Arabic al-firq, “the flock”, from an old picture of shepherd and sheep in this region. It also has a companion visible in a telescope.
What you see in the piece
Alfirk lies much further away than Alderamin, so the two stars that look like neighbours in Cepheus pull apart when you fly out. Its colour is its heat, drawn blue-white.
Questions
What is a Beta Cephei variable?
A Beta Cephei variable is a hot, massive star that pulsates with small, regular changes in brightness over hours. The class is named after Alfirk, Beta Cephei.