Hadar is the second brightest star of Centaurus, a hot blue-white giant system that with Alpha Centauri points the way to the Southern Cross.
At a glance
| type | blue-white giant (class B) |
|---|---|
| distance from the Sun | 392 light-years (120 pc) |
| its light left it | 392 years ago |
| luminosity | 68,600 × the Sun |
| radius | 13.5 × the Sun |
| surface temperature | 25,400 K |
| constellation | Centaurus (Centaur) |
Read off the piece’s own catalogue, the same values it draws with.
About Hadar
Hadar is a blue-white giant of class B, enormously more luminous than the Sun. It is a system of three stars: two very similar hot giants in a tight orbit, too close to separate except with interferometers, and a fainter companion further out. Its brightness also pulses slightly, as many hot stars of its kind do.
Hadar and Alpha Centauri, the brightest stars of Centaurus, are the Pointers: a line from Alpha Centauri through Hadar leads to the Southern Cross. The pair look alike on the sky, yet Alpha Centauri is one of the Sun’s nearest neighbours, while Hadar lies far beyond it.
Its other traditional name is Agena. Hadar is one of the stars used for celestial navigation.
What you see in the piece
The two Pointers sit side by side from Earth. In the piece Alpha Centauri is a nearby star you can reach in a moment; Hadar stays a distant blue point for far longer, a far more powerful star.
Measured or modelled
The card treats Hadar as one star; its luminosity is shared among its members according to models of the system.
Questions
What are the Pointers?
Alpha Centauri and Hadar: a line from Alpha Centauri through Hadar points to the Southern Cross.
How far away is Hadar?
Hadar is 392 light-years (120 pc) from the Sun.