Altair is the brightest star in Aquila, a nearby white star spinning so fast that it is visibly flattened and hotter at its poles than its equator.
At a glance
| type | white star (class A) |
|---|---|
| distance from the Sun | 16.7 light-years (5.13 pc) |
| its light left it | 16.7 years ago |
| luminosity | 10.6 × the Sun |
| radius | 1.79 × the Sun |
| surface temperature | 7,550 K |
| constellation | Aquila (Eagle) |
Read off the piece’s own catalogue, the same values it draws with.
About Altair
Altair is a main-sequence star hotter and larger than the Sun, and it is one of the closest stars visible to the naked eye. With Vega and Deneb it forms the Summer Triangle, the large figure that dominates northern summer skies.
Its rotation is extremely fast. The spin flattens it so that its equator bulges outwards, and the equator, being farther from the centre, is cooler and darker than the poles: an effect called gravity darkening. Interferometers, which combine light from several telescopes, have produced images of its surface showing this flattened shape directly.
What you see in the piece
From Earth, with HUMAN EYE on, it is one of the brightest points in the sky, white against the Milky Way. Fly to it and it becomes a bright white disc.
Questions
Why is Altair flattened?
Altair spins so fast that its equator bulges outwards, making it wider at the equator than from pole to pole; interferometers have imaged this shape.