Lambda Cygni

Lambda Cygni

Observation data Epoch J2000      Equinox J2000
Constellation	Cygnus
Right ascension	20^h 47^m 24.53766^s [1]
Declination	36° 29′ 26.5737″ [1]
Apparent magnitude (V)	4.54 [2]
Characteristics
Spectral type	B5V [3]
U−B color index	-0.50 [2]
B−V color index	-0.11 [2]
Astrometry
Radial velocity (Rv)	-23.20[4] km/s
Proper motion (μ)	RA: +14.71[5] mas/yr Dec.: -8.96[5] mas/yr
Parallax (π)	4.24 ± 0.43[1] mas
Distance	approx. 770 ly (approx. 240 pc)
Absolute magnitude (MV)	-2.32 [6]
Details
Radius	3.56 [7] R☉
Other designations
54 Cygni, CCDM J20475+3629ABP, GC 28994, HIP 102589, HR 7963, HD 198183, SAO 70505, WDS J20474+3629AB [5]
Database references
SIMBAD	data

Lambda Cygni (λ Cyg) is a class B5V^[3] (blue main-sequence) star in the constellation Cygnus. Its apparent magnitude is 4.54^[2] and it is approximately 770 light years away based on parallax.^[1]

Lambda Cygni is a multiple star, with components A, B, and C observed in the 19th century; the main component, A, is a spectroscopic binary itself with two components Aa and Ab reported at magnitudes 5.4 and 5.8 orbiting with a period of 12 years.^[8] Component B has type B7V, magnitude 6.26, and separation 0.77" (about 180 AU based on parallax).^[9][8] Component C has reported type K2III-IV, apparent magnitude 9.65, and separation about 85".^[10] Recent observations indicate the presence of additional smaller companions D (about 50" from A), E (about 8" from C), and F (about 40" from C) all around apparent magnitude 14.^[10]

References

1. van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. Vizier catalog entry
2. Ducati, J. R. (2002). "VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system". CDS/ADC Collection of Electronic Catalogues 2237: 0. Bibcode:2002yCat.2237....0D.
3. Slettebak, A. (September 1982), "Spectral types and rotational velocities of the brighter Be stars and A-F type shell stars", Astrophysical Journal Supplement Series 50: 55–83, Bibcode:1982ApJS...50...55S, doi:10.1086/190820
4. Kharchenko, N. V.; et al. (2007), "Astrophysical supplements to the ASCC-2.5: Ia. Radial velocities of ˜55000 stars and mean radial velocities of 516 Galactic open clusters and associations", Astronomische Nachrichten 328 (9): 889, arXiv:0705.0878, Bibcode:2007AN....328..889K, doi:10.1002/asna.200710776
5. "Lambda Cygni". SIMBAD Astronomical Database. Retrieved 2016-04-08.
6. Absolute magnitude calculated as $M = m + 5 (1 + \log_{10}{p})\!\,$, where $M$ is the star's absolute magnitude, $m$ is the star's apparent magnitude, and $p$ is the star's measured parallax in arcseconds.
7. Pasinetti Fracassini, L. E.; Pastori, L.; Covino, S.; Pozzi, A. (February 2001), "Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS) - Third edition", Astronomy and Astrophysics 367: 521–524, arXiv:astro-ph/0012289, Bibcode:2001A&A...367..521P, doi:10.1051/0004-6361:20000451 Vizier catalog entry
8. Malkov, O. Yu.; et al. (October 2012), "Dynamical masses of a selected sample of orbital binaries", Astronomy & Astrophysics 546 (A69), Bibcode:2012A&A...546A..69M, doi:10.1051/0004-6361/201219774 Vizier catalog entry
9. Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society 389 (2): 869–879, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x Vizier catalog entry
10. Mason, Brian D.; et al. (December 2001), "The 2001 US Naval Observatory Double Star CD-ROM. I. The Washington Double Star Catalog", The Astronomical Journal 122 (6): 3466–3471, Bibcode:2001AJ....122.3466M, doi:10.1086/323920 Vizier catalog entry