Mirach is the red giant in the middle of Andromeda’s line of stars, the signpost observers use to find the Andromeda Galaxy beside it.
At a glance
| type | red giant (class M) |
|---|---|
| distance from the Sun | 197 light-years (60.5 pc) |
| its light left it | 197 years ago |
| luminosity | 1,390 × the Sun |
| radius | 86.1 × the Sun |
| surface temperature | 3,800 K |
| constellation | Andromeda (Chained Maiden) |
Read off the piece’s own catalogue, the same values it draws with.
About Mirach
Mirach is a red giant of class M, a cool star near the boundary between orange and red that that has exhausted its core hydrogen and swollen to many times the Sun’s width. Its large surface makes it luminous despite being cooler than the Sun, and it is the second brightest star of Andromeda.
The name is a corrupted form of an Arabic word for a girdle or loincloth, describing where it lies in the figure of the chained princess, at her hip. From Mirach, a short line through the fainter Mu Andromedae leads to the Andromeda Galaxy. Close beside it in the sky lies a small galaxy, NGC 404, nicknamed Mirach’s Ghost because the star’s glare nearly hides it.
What you see in the piece
From Earth Mirach and the Andromeda Galaxy seem to sit side by side. In the piece the star is a near neighbour in our own galaxy and the galaxy is vastly farther off, so the two separate completely the moment you move.
Questions
How do you find the Andromeda Galaxy from Mirach?
Start at Mirach, go to the fainter star Mu Andromedae just above it, and continue the same distance again: the galaxy is the misty patch there.
How big is Mirach?
Mirach’s radius is 86.1 times the Sun’s, and it shines 1,390 times as brightly.