70 Ophiuchi A is a nearby orange star with a close companion, a double whose orbit was followed for so long that it once fooled astronomers into seeing a planet.
At a glance
| type | orange star (class K) |
|---|---|
| distance from the Sun | 16.6 light-years (5.1 pc) |
| its light left it | 16.6 years ago |
| luminosity | 0.47 × the Sun |
| radius | 0.83 × the Sun |
| surface temperature | 5,300 K |
Read off the piece’s own catalogue, the same values it draws with.
About 70 Ophiuchi A
70 Ophiuchi A is an orange main-sequence star of class K, a little smaller and cooler than the Sun. It forms a binary with 70 Ophiuchi B, a smaller orange dwarf, the two circling each other in a slow orbit that has been followed through more than one full turn.
Long before planets around other stars could truly be detected, observers claimed that irregularities in the pair’s orbit revealed an unseen third body. Those claims did not hold up; the orbit was later shown to need no extra companion. The episode became a well-known caution about over-reading small measurement errors.
What you see in the piece
From Earth the pair shows in the piece as a single faint point in Ophiuchus. Fly to it and A and B separate, an orange star with a smaller, cooler partner.
Questions
Is 70 Ophiuchi a binary star?
Yes. 70 Ophiuchi A and B orbit each other, a pair of stars slightly smaller and cooler than the Sun.