HD 1976
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Cassiopeia |
| Right ascension | 00h 24m 15.65400s |
| Declination | +52° 01′ 11.7032″ |
| Apparent magnitude (V) | 5.580 (combined) |
| Characteristics | |
| Spectral type | (B5IV + unknown) + ~B5-6IV |
| U−B color index | −0.619 |
| B−V color index | −0.121 |
| J−H color index | −0.102 |
| J−K color index | −0.106 |
| Variable type | Slowly pulsating B-type star (A; disputed) |
| Astrometry | |
| Radial velocity (Rv) | −9.70±0.49 km/s |
| Proper motion (μ) | RA: 15.504 mas/yr Dec.: −4.061 mas/yr |
| Parallax (π) | 2.4621±0.33 mas |
| Distance | approx. 1,300 ly (approx. 410 pc) |
| Orbit | |
| Primary | HD 1976 Aa |
| Companion | HD 1976 Ab |
| Period (P) | 25.4163±0.0008 d |
| Semi-major axis (a) | 0.42±0.05 mas |
| Eccentricity (e) | 0.05±0.03 |
| Inclination (i) | 100.7±1.2° |
| Longitude of the node (Ω) | 339.9±1.1° |
| Periastron epoch (T) | 59477±5 |
| Argument of periastron (ω) (secondary) | 61±52° |
| Orbit | |
| Primary | HD 1976 A |
| Companion | HD 1976 B |
| Period (P) | 171±3 yr |
| Semi-major axis (a) | 208.0±2.7 mas |
| Eccentricity (e) | 0.162±0.008 |
| Inclination (i) | 62.8±0.4° |
| Longitude of the node (Ω) | 27.8±0.4° |
| Periastron epoch (T) | 33710±679 |
| Argument of periastron (ω) (secondary) | 306.0±4° |
| Details | |
| HD 1976 Aa | |
| Mass | 6.45±0.17, 6.348 M☉ |
| Radius | 5.24+0.14 −0.10 R☉ |
| Surface gravity (log g) | 3.81±0.01 cgs |
| Temperature | 16526+100 −82 K |
| Rotational velocity (v sin i) | 170±4 km/s |
| Age | ~60 Myr |
| HD 1976 Ab | |
| Mass | 1.83, 4.0±0.7 M☉ |
| Radius | 1.83 R☉ |
| Surface gravity (log g) | 4.18 cgs |
| Temperature | 8071+266 −352 K |
| Rotational velocity (v sin i) | 165 km/s |
| HD 1976 B | |
| Mass | 6.10+0.27 −0.26 M☉ |
| Radius | 4.48±0.20 R☉ |
| Surface gravity (log g) | 3.92±0.02 cgs |
| Temperature | 13620+154 −144 K |
| Rotational velocity (v sin i) | 73+6 −5 km/s |
| Other designations | |
| V746 Cassiopeiae, AG+51°39, BD+51°62, Gaia DR3 418916648901801728, GC 476, HD 1976, HIP 1921, HR 91, SAO 21366, PPM 25297, WDS J00243+5201AB, TIC 202418751, TYC 3260-2342-1, GSC 03260-02342, 2MASS J00241564+5201119, ADS 328 | |
| Database references | |
| SIMBAD | HD 1976 |
HD 1976 is a hierarchical triple system in the deep northern constellation of Cassiopeia, somewhere around 1,100 light-years (340 parsecs) from Earth. It has the variable-star designation V746 Cassiopeiae (abbreviated to V746 Cas). The system is faintly visible to the naked eye under dark skies, having an apparent magnitude of 5.580. It consists of an inner pair between a B-type subgiant and a less massive unknown-type star, which is distantly orbited by another B-type subgiant. It is currently moving closer towards the Solar System at a heliocentric radial velocity of −9.70 km/s.