HD 2942
Triple star system in the constellation Andromeda
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HD 2942 is a triple star system[5] in the constellation Andromeda located approximately 170 parsecs (550 ly) away.
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Andromeda[1] |
| A | |
| Right ascension | 00h 32m 49.0863s[2] |
| Declination | +28° 16′ 48.868″[2] |
| Apparent magnitude (V) | 6.33[3] |
| B | |
| Right ascension | 00h 32m 49.3227s[4] |
| Declination | +28° 16′ 40.831″[4] |
| Apparent magnitude (V) | 11.26[5] |
| Characteristics | |
| Spectral type | K0III+G6V+G8V[5] |
| U−B color index | 0.80[3] |
| B−V color index | 0.99[3] |
| Astrometry | |
| A | |
| Radial velocity (Rv) | −10.50±0.14[2] km/s |
| Proper motion (μ) | RA: −5.695±0.072[2] mas/yr Dec.: 6.101±0.039[2] mas/yr |
| Parallax (π) | 5.8690±0.0434 mas[2] |
| Distance | 556 ± 4 ly (170 ± 1 pc) |
| Orbit[5] | |
| Primary | HD 2942Ba |
| Name | HD 2942Bb |
| Period (P) | 7.4887 days |
| Eccentricity (e) | 0.055 |
| Periastron epoch (T) | HJD 2,451,060.5586 |
| Argument of periastron (ω) (secondary) | 293.40° |
| Semi-amplitude (K1) (primary) | 64.01 km/s |
| Semi-amplitude (K2) (secondary) | 66.34 km/s |
| Details[5] | |
| HD 2942A | |
| Mass | 3.17 M☉ |
| HD 2942B | |
| Mass | 0.89 (Ba) 0.85 (Bb) M☉ |
| Other designations | |
| HIP 2583, HR 134, BD+27°84, SAO 74090, WDS J00328+2817A | |
| Database references | |
| SIMBAD | A |
| B | |
The primary component, a red giant of spectral type K0III, has an apparent magnitude of 6.33, meaning that it is barely visible with the naked eye under good conditions.[3]
The secondary component is much fainter, with an apparent magnitude 11.26, and is located 8.6 arcseconds away. It is a double-lined spectroscopic binary, where two very similar G-type main sequence stars of spectral types G6V and G8V orbit around their common center of mass in 7.489 days. The pair complete an orbit around the primary star every 24,762 years.[5]
Catalogues of stellar multiplicity, like the Washington Double Star Catalog, usually list another component; this star, however, is located much more far away than the other two.[6]