Star profile
Omicron Andromedae
Variable starWhat is Omicron Andromedae
Omicron Andromedae, also catalogued as 1 Andromedae, is a blue giant about 687 light-years away, set in the chained silhouette of the mythological princess. It belongs to the Be class: spinning so violently that a ring of glowing hydrogen escapes from its equator, causing the faintest of slow flickers across centuries. The light reaching us tonight left during the European Middle Ages, long before any telescope could pick out the red signature of hydrogen in its spectrum.
Where it is and when to see it
Omicron Andromedae lies in the northern celestial hemisphere. It is visible to the naked eye under a dark sky. Its best month of the year is October, when it culminates around midnight.
- From London it never sets and culminates about 81° up.
- From New York it culminates about 88° above the horizon.
- From Sydney it culminates about 14° above the horizon.
It can be seen from anywhere north of 48° S.
It ranks no. 6 in brightness among the 81 stars of Andromeda in our catalogue. To find it, start from Alpheratz, the brightest: it lies about 19° away (a fist at arm's length covers about 10°).
The light you see today left it about 690 years ago.
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Astronomical data for Omicron Andromedae
- Constellation
- Andromeda
- Apparent magnitude
- 3.62
- Distance
- 686.7 light years
- Coordinates (J2000)
- RA 345.480° · Dec 42.326°
- Catalogue
- HIP 113726 · HD 217675
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Other stars in Andromeda
Andromeda has 81 stars in Stelvia's catalogue. Here are a few of them.
- MirachBeta Andromedae2.07
- AlpheratzAlpha Andromedae2.07
- AlmachGamma 1 Andromedae2.10
- Delta Andromedae3.27
- Nembus3.59
- Lambda Andromedae3.81
- Mu Andromedae3.86
- Zeta Andromedae4.08