VV Cephei , also known as HD 208816 , is an eclipsing binary star system located in the constellation Cepheus . It is both a B[e] star and shell star .
Quick Facts Observation data Epoch J2000 Equinox J2000, Constellation ...
VV Cephei
Location of VV Cephei in Cepheus constellation
Observation dataEpoch J2000 Equinox J2000
Constellation
Cepheus
Right ascension
21h 56m 39.14385s [1]
Declination
+63° 37′ 32.0174″ [1]
Apparent magnitude (V)
4.91[2] (4.80 - 5.36[3] )
Characteristics
U−B color index
+0.43[4]
B−V color index
+1.73[4]
Variable type
EA + SRc [3]
A
Evolutionary stage
Red supergiant
Spectral type
M2 Iab[2] (M1p 0)[5]
U−B color index
+2.07[4]
B−V color index
+1.82[4]
B
Evolutionary stage
B-type main-sequence star
Spectral type
B0-2 V[2]
U−B color index
−0.52[4]
B−V color index
+0.36[4]
Astrometry Proper motion (μ) RA: −1.066[6] mas /yr Dec.: −0.425[6] mas /yr Parallax (π)1.0033 ± 0.1073 mas [6] Distance 3,319+463 −323 – 4900 ly ( 1,018+142 −99 [7] – 1500[8] pc )Absolute magnitude (MV )−6.93[9]
Orbit Period (P)7,430.5 days[10] Semi-major axis (a)16.2 ± 3.7[2] " (24.8[11] AU) Eccentricity (e)0.346 ± 0.01[10] Inclination (i)84[8] ° Semi-amplitude (K1 ) (primary)19.43 ± 0.33[10] km/s Semi-amplitude (K2 ) (secondary)19.14 ± 0.68[10] km/s
Details A Mass 18.2[11] or 2.5[12] M ☉ Radius 779+77 −96 ,[13] 1,050[8] R ☉ Luminosity 116,000[14] L ☉ Surface gravity (log g )–0.26[14] cgs Temperature 3,660[15] (3,480[16] – 3,826[2] ) K Metallicity [Fe/H]−0.06[17] dex Age 25± 0.1[18] Myr B Mass 18.6[11] or 8[12] M ☉ Radius 13[10] or 25[19] R ☉ Metallicity [Fe/H]−0.14[20] dex Age 25± 0.1[18] Myr
Other designations VV Cep,
HR 8383,
HIP 108317,
HD 208816,
BD +62°2007,
WDS J21567+6338,
2MASS J21563917+6337319,
IRAS 21552+6323,
AAVSO 2153+63,
Gaia DR3 2216536246703152256,
Gaia DR2 2216536246703152256
Database references SIMBAD data
Close
VV Cephei is an eclipsing binary with the third longest known period. A red supergiant fills its Roche lobe when closest to a companion blue star, the latter appearing to be on the main sequence . Matter flows from the red supergiant onto the blue companion for at least part of the orbit and the hot star is obscured by a large disk of material. The supergiant primary, known as VV Cephei A, is currently recognised as one of the largest stars in the galaxy although its size is not certain. Estimates range from 780 R ☉ to over 1,000 R ☉ .