Antares B is the hot blue-white companion of the red supergiant Antares, a bright star in its own right that looks faint only because of its neighbour.
At a glance
| type | blue-white star (class B) |
|---|---|
| distance from the Sun | 554 light-years (170 pc) |
| its light left it | 554 years ago |
| luminosity | 2,750 × the Sun |
| radius | 5.2 × the Sun |
| surface temperature | 18,500 K |
Read off the piece’s own catalogue, the same values it draws with.
About Antares B
Antares B is a hot, young B-type star on a wide orbit around Antares, far enough out that a good telescope can split the pair on a steady night. It is much hotter than the supergiant and many times more luminous than the Sun, yet beside Antares it is easy to miss.
It is often described as green. That colour is an effect of contrast: next to the deep orange of Antares, a blue-white star looks greenish to the eye. It was first noticed when the Moon passed in front of Antares, briefly hiding the supergiant and leaving its companion visible for a moment.
Antares sheds gas in a slow wind, and Antares B sits inside that outflow. Its ultraviolet light ionises a patch of the shed material, making it glow, a small nebula lit by one star from the wind of another.
What you see in the piece
Fly to Antares and B appears beside it as a blue-white point; its true colour is its temperature, not the green seen through telescopes from Earth.
Questions
Why does Antares B look green?
It does not really. It is a blue-white star, and its colour looks green to the eye only by contrast with the deep orange of Antares beside it.
How hot is Antares B?
Its surface is about 18,500 K, far hotter than Antares, and it shines 2,750 × the Sun.