Lambda Cassiopeiae

λ Cassiopeiae

Map of the Bayer-designated stars in Cassiopeia. Lambda Cassiopeiae is circled.
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Cassiopeia
Right ascension 00h 31m 46.35935s[1]
Declination +54° 31′ 20.2257″[1]
Apparent magnitude (V) 4.772[2]
(5.33 / 5.62)[3]
Characteristics
Spectral type B8 Vnn[4]
U−B color index −0.35[5]
B−V color index −0.10[5]
Astrometry
Radial velocity (Rv)−12.20±1.3[6] km/s
Proper motion (μ) RA: +41.20±0.29[1] mas/yr
Dec.: −16.54±0.35[1] mas/yr
Parallax (π)8.64 ± 0.43 mas[1]
Distance380 ± 20 ly
(116 ± 6 pc)
Absolute magnitude (MV)−0.57[4]
Orbit[3]
Period (P)245.70±35.96 yr
Semi-major axis (a)0.448±0.028″
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 (ω)
(secondary)		301.0±2.6°
Details
λ Cas A
Mass2.9+0.45
−0.40[7] M☉
Radius3.50[8] R☉
Luminosity255[4] L☉
Surface gravity (log g)4.0±0.25[7] cgs
Temperature12,000±1,000[7] K
Rotational velocity (v sin i)253[9] km/s
Age58+104
−48[7] Myr
Other designations
λ Cas, 14 Cassiopeiae, BD+53°82, HD 2772, HIP 2505, HR 123, SAO 21489, ADS 434, CCDM J00318+5431
Database references
SIMBADλ Cas
λ Cas A
λ Cas B
λ Cassiopeiae in optical light

Lambda Cassiopeiae, Latinized from λ Cassiopeiae, is a binary star system, in the northern constellation of Cassiopeia. 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 mass,[1] it is approximately 380 light years from Earth. The system is moving closer to the Sun with a radial velocity of −12 km/s.[6]

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.[3] The primary displays an infrared excess, possibly due to a debris disk or other orbiting material.[8]

  1. ^ a b c d e f Cite error: The named reference van Leeuwen2007 was invoked but never defined (see the help page).
  2. ^ Cite error: The named reference TYC2 was invoked but never defined (see the help page).
  3. ^ a b c Cite error: The named reference ORB6 was invoked but never defined (see the help page).
  4. ^ a b c Cite error: The named reference Anderson2012 was invoked but never defined (see the help page).
  5. ^ a b Mermilliod, J.-C. (1986). "Compilation of Eggen's UBV data, transformed to UBV (unpublished)". Catalogue of Eggen's UBV Data. Bibcode:1986EgUBV........0M.
  6. ^ a b Cite error: The named reference Kharchenko was invoked but never defined (see the help page).
  7. ^ a b c d Gullikson, Kevin; et al. (August 2016). "The Close Companion Mass-ratio Distribution of Intermediate-mass Stars". The Astronomical Journal. 152 (2): 13. arXiv:1604.06456. Bibcode:2016AJ....152...40G. doi:10.3847/0004-6256/152/2/40. S2CID 119179065. 40.
  8. ^ a b Cotten, Tara H.; Song, Inseok (July 2016), "A Comprehensive Census of Nearby Infrared Excess Stars", The Astrophysical Journal Supplement Series, 225 (1): 24, arXiv:1606.01134, Bibcode:2016ApJS..225...15C, doi:10.3847/0067-0049/225/1/15, S2CID 118438871, 15
  9. ^ Zorec, J.; Royer, F. (January 2012), "Rotational velocities of A-type stars. IV. Evolution of rotational velocities", Astronomy & Astrophysics, 537: A120, arXiv:1201.2052, Bibcode:2012A&A...537A.120Z, doi:10.1051/0004-6361/201117691, S2CID 55586789.