VV Cephei
Location of VV Cephei in Cepheus constellation | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Cepheus |
| Right ascension | 21h 56m 39.14385s |
| Declination | +63° 37′ 32.0174″ |
| Apparent magnitude (V) | 4.91 (4.80 - 5.36) |
| Characteristics | |
| U−B color index | +0.43 |
| B−V color index | +1.73 |
| Variable type | EA + SRc |
| A | |
| Evolutionary stage | Red supergiant |
| Spectral type | M2 Iab (M1p 0) |
| U−B color index | +2.07 |
| B−V color index | +1.82 |
| B | |
| Evolutionary stage | B-type main-sequence star |
| Spectral type | B0-2 V |
| U−B color index | −0.52 |
| B−V color index | +0.36 |
| Astrometry | |
| Proper motion (μ) | RA: −1.066 mas/yr Dec.: −0.425 mas/yr |
| Parallax (π) | 1.0033±0.1073 mas |
| Distance | 3,319 – 4900 ly (1,018+142 −99 – 1500±400 pc) |
| Absolute magnitude (MV) | −6.93 |
| Orbit | |
| Period (P) | 7,430.5 days |
| Semi-major axis (a) | 16.2 ± 3.7" (24.8 AU) |
| Eccentricity (e) | 0.346 ± 0.01 |
| Inclination (i) | 84° |
| Semi-amplitude (K1) (primary) | 19.43 ± 0.33 km/s |
| Semi-amplitude (K2) (secondary) | 19.14 ± 0.68 km/s |
| Details | |
| A | |
| Mass | 2.5 or 18.2 M☉ |
| Radius | 660, 1,050 R☉ |
| Luminosity | 72,880±16,300 L☉ |
| Surface gravity (log g) | –0.26 cgs |
| Temperature | 3,660 – 3,826 K |
| Metallicity [Fe/H] | −0.06 dex |
| Age | 25±0.1 Myr |
| B | |
| Mass | 8 or 18.6 M☉ |
| Radius | 13 or 25 R☉ |
| Metallicity [Fe/H] | −0.14 dex |
| Age | 25±0.1 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 |
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. As a 5th magnitude star, it is visible to the naked eye under good observing conditions.
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 660 R☉ to over 1,000 R☉.