  | |
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Coma Berenices |
| Right ascension | 12h 22m 30.31076s[1] |
| Declination | +25° 50′ 46.1896″[1] |
| Apparent magnitude (V) | 4.80[2] |
| Characteristics | |
| Spectral type | G7 III + A3 V[3] |
| U−Bcolor index | 0.47/0.09[2] |
| B−Vcolor index | 0.82/0.11[2] |
| Astrometry | |
| Radial velocity (Rv) | +0.5±0.9[4] km/s |
| Proper motion (μ) | RA: −10.847[1]mas/yr Dec.: −9.546[1]mas/yr |
| Parallax (π) | 11.8280±0.2353 mas[1] |
| Distance | 276 ± 5 ly (85 ± 2 pc) |
| Absolute magnitude (MV) | 0.55±0.06 /1.05±0.06[2] |
| Orbit[3] | |
| Period (P) | 396.4473±0.0002 d |
| Semi-major axis (a) | 20.3358±0.00066 |
| Eccentricity (e) | 0.599483±0.000026 |
| Inclination (i) | 64.8556±0.0011° |
| Longitude of the node (Ω) | 118.618±0.004° |
| Periastronepoch (T) | 46877.148±0.054 MJD |
| Argument of periastron (ω) (primary) | 100.162±0.001° |
| Semi-amplitude (K1) (primary) | 22.42±2.22 km/s |
| Details | |
| 12 Com A | |
| Mass | 2.64±0.07[3] M☉ |
| Radius | 8.36±0.15[3] R☉ |
| Luminosity | 56.2+2.7 −2.5[2] L☉ |
| Temperature | 5,300±200[2] K |
| Age | 533 ± 41 ± 42[3] Myr |
| 12 Com B | |
| Mass | 2.10±0.03[3] M☉ |
| Radius | 2.5±0.3[2] R☉ |
| Luminosity | 30.2+2.2 −2.2[2] L☉ |
| Temperature | 8,500±500[2] K |
| Other designations | |
| 12 Com,NSV 5581,BD+26°2337,FK5 1318,HD 107700,HIP 60351,HR 4707,SAO 82273,WDS J12225+2551A[5] | |
| Database references | |
| SIMBAD | data |
12 Comae Berenices is abinary star system in the northernconstellation ofComa Berenices. It is the brightest member of theComa Star Cluster and is visible to the naked eye with anapparent visual magnitude of 4.80.[2] Although listed as a suspectedvariable star, there is nophotometric evidence of it being variable in luminosity. However, theradial velocity was found to be variable, as announced byW. W. Campbell in 1910. The first orbital solution was published byVinter Hansen in the 1940s.[2] It is a double-linedspectroscopic binary with anorbital period of 396.5 days and aneccentricity of 0.566.[6]
This system consists of twostars, anevolvedG-typegiant star and a smaller but higher temperatureA-type main-sequence star.[7] Griffin and Griffin (2011) suggested that the secondary component may have begun its evolution away from the main sequence, and instead assigned it aluminosity class of IV. The primary, designated component A, has about 2.6 times themass of the Sun and has expanded to 8.4 times theSun's radius. It is radiating 56 times theSun's luminosity from its enlargedphotosphere at aneffective temperature of 5,300 K. Its companion, component B, has double the Sun's mass and 2.5 times the radius. It shines with 30 times the luminosity of the Sun at 8,500 K.[2]
