Star profile
15 Monocerotis
Variable starWhat is 15 Monocerotis
Also catalogued as S Monocerotis, 15 Monocerotis is the brightest star of the Christmas Tree Cluster —NGC 2264—, the cluster of young suns that traces the triangular outline of the famous asterism. Since 1943 it has served as the MK spectral standard for type O7 against which other massive stars are calibrated. It is also a binary with an orbital period near 112 years, and its blue light has crossed roughly seven centuries to reach us.
Where it is and when to see it
15 Monocerotis lies in the northern celestial hemisphere. It is visible to the naked eye under a dark sky. Its best month of the year is January: the Sun sits at the opposite point of the sky and the star culminates around midnight. How high it climbs above the horizon depends on the latitude you watch from.
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The signature wall
Stelvia's sky works like a signature wall: anyone can leave their name and a message on a real star, and that signature goes up on the map for everyone to read. Signing is free.
A signature without a lock can be replaced by someone else's. The lock makes the signature permanent and lets you choose a symbolic name for the star, always shown next to the star's catalogue identifier. How the lock works
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A public signature from a real person. The chosen name is a symbolic denomination within Stelvia, with no official standing or IAU recognition: the sky is not for sale and belongs to no one.
Astronomical data for 15 Monocerotis
- Constellation
- Monoceros
- Apparent magnitude
- 4.66
- Distance
- 918.9 light years
- Coordinates (J2000)
- RA 100.244° · Dec 9.896°
- Catalogue
- HIP 31978 · HD 47839
A symbolic commemorative gift: neither the signature nor the chosen name implies ownership of the star or recognition by the IAU.
Other stars in Monoceros
Monoceros has 71 stars in Stelvia's catalogue. Here are a few of them.
- Beta Monocerotis3.76
- Alpha Monocerotis3.94
- Gamma Monocerotis3.99
- Epsilon Monocerotis4.39
- 13 Monocerotis4.47
- 18 Monocerotis4.48
- 28 Monocerotis4.69
- 17 Monocerotis4.77