Coma Berenices boasts a double star, known as 12 Comae Berenices, situated in the northern region of the constellation. Amateur stargazers can easily spot this celestial body using binoculars or compact telescopes during spring evenings.
At a fairly bright magnitude of +4.8, 12 Comae Berenices is one of the brighter stars in its faint springtime constellation. The primary star is a yellow giant, classified as spectral type G0III. In contrast, the secondary star is a dimmer magnitude of +8.51 and lies 36 arcseconds away. The greater distance between the two objects enables novice stargazers to distinguish them with ease.1
Of note, it appears that 12 Comae Berenices is also a spectroscopic binary. This means there is another star closely orbiting the primary. It’s so close and faint, we cannot view it through our telescopes. Only special equipment can pick up evidence of the smaller star’s presence.
My Observations
| Date | April 28, 2023 |
| Time | 10:45 p.m. |
| Location | Seattle, WA |
| Magnification | 169x |
| Scope | Meade 8″ SCT |
| Eyepiece | 12mm |
| Seeing | Average |
| Transparency | Below Average |
This double star, somewhat like the nearby 24 Comae Berenices, features an amber-looking and bright primary star that sits above the dimmer secondary, which appears white to me. Despite the waxing half-moon, I can still discern a few extra stars in the field, illuminated by the moon’s gentle glow.
I lament this moment as I finish the sketch. My time at the scope tonight has been short (about an hour). An hour ago, when I started observing, the skies were perfectly clear. Now, a cloud layer sneaks in the front south, and it’s just starting to wash over Coma Berenices.
Key Stats
| Constellation | Coma Berenices |
| Best Viewing | Spring |
| Visual Magnitude | +4.80 | +11.80 |
| Absolute Visual Magnitude | +.02 |
| Separation | 36.7″ |
| Position Angle | 57° |
| Distance from Earth | 265 ly |
| Orbital Period | Unknown |
| Milky Way Location | Orion Spur |
| My Viewing Grade | A |
| Designations | SAO 82273, HD 107700, HR 4707, HIP 60351 |
Sources and Notes
The 12 Comae Berenices banner is produced from a photo from David Ritter, photographed from Edmonton, Canada, on the night of April 8, 2019. The photo is licensed under the Creative Commons Attribution-Share Alike 4.0 International license. Additional details are here.
1 12 Comae Berenices – Star in coma berenices. Star in Coma Berenices | TheSkyLive.com. (n.d.). Retrieved April 29, 2023, from https://theskylive.com/sky/stars/12-comae-berenices-star
Sketch by Wayne McGraw
The Garden Astronomer 