Lambda Cassiopeiae
Star system in Cassiopeia
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Lambda Cassiopeiae is a binary star system in the northern constellation of Cassiopeia. Its name is a Bayer designation that is Latinized from λ Cassiopeiae, and abbreviated Lambda Cas or λ Cas. The system has a combined apparent magnitude of +4.74, making it faintly visible to the naked eye. With an annual parallax shift of 8.64 mas,[2] it is approximately 380 light years from Earth. The system is moving closer to the Sun with a radial velocity of â12 km/s.[6]
(5.33 / 5.62)[4]
  | |
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Cassiopeia[1] |
| Right ascension | 00h 31m 46.35935s[2] |
| Declination | +54° 31â² 20.2257â³[2] |
| Apparent magnitude (V) | 4.772[3] (5.33 / 5.62)[4] |
| Characteristics | |
| Spectral type | B8 Vnn[1] |
| UâB color index | â0.35[5] |
| BâV color index | â0.10[5] |
| Astrometry | |
| Radial velocity (Rv) | â12.20±1.3[6] km/s |
| Proper motion (μ) | RA: +41.20±0.29[2] mas/yr[2] Dec.: â16.54±0.35 mas/yr[2] |
| Parallax (Ï) | 8.64±0.43 mas[2] |
| Distance | 380 ± 20 ly (116 ± 6 pc) |
| Absolute magnitude (MV) | â0.57[1] |
| Orbit[4] | |
| Period (P) | 245.70±35.96 yr |
| Semi-major axis (a) | 0.448±0.028Ⳡ|
| Eccentricity (e) | 0.689±0.119 |
| Inclination (i) | 53.6±5.2° |
| Longitude of the node (Ω) | 17.6±9.6° |
| Periastron epoch (T) | 2025.54±4.56 |
| Argument of periastron (Ï) (secondary) | 301.0±2.6° |
| Details | |
| λ Cas A | |
| Mass | 2.9+0.45 â0.40[7] Mâ |
| Radius | 3.50[8] Râ |
| Luminosity | 255[1] Lâ |
| Surface gravity (log g) | 4.0±0.25[7] cgs |
| Temperature | 12,000±1,000[7] K |
| Rotational velocity (v sin i) | 253[9] km/s |
| Age | 58+104 â48[7] Myr |
| Other designations | |
| λ Cas, 14 Cassiopeiae, BD+53°82, HD 2772, HIP 2505, HR 123, SAO 21489, ADS 434, CCDM J00318+5431, WDS J00318+5431AB[10] | |
| Database references | |
| SIMBAD | λ Cas |
| λ Cas A | |
| λ Cas B | |
Both components are blue-white B-type main-sequence stars. The brighter member, component A, has an apparent magnitude of +5.5, while its companion, component B, has an apparent magnitude of +5.8. The two stars are separated by 0.6 arcseconds and complete one orbit around their common centre of mass about once every 250 years.[4] The primary displays an infrared excess, possibly due to a debris disk or other orbiting material.[8]