VV Cephei, a red supergiant star in Cepheus
VV Cephei is a red supergiant star in the constellation Cepheus. At 3,251 light years away, it shines at an apparent visual magnitude of 4.90.
VV Cephei (HIP 108317)
VV Cephei is a red supergiant star in the constellation Cepheus. At 3,251 light years away, it shines at an apparent visual magnitude of 4.90. It is moving through the Galaxy at a speed of 19.5 km/s relative to the Sun.
Sky position: RA 21h 56.7m, Dec +63° 37.5'
Common designations: VV Cephei, HR 8383, HD 208816, Gaia DR3 2216536246703152256, HIP 108317
VV Cephei has the spectral type M2Ibep+B2?ep_sh. M-type stars are cool red stars below about 3,900 K whose spectra are dominated by titanium oxide molecular bands. Red dwarfs, red giants and red supergiants all fall in this class. Its luminosity class I marks it as a supergiant, among the most luminous and largest stars known.
How to find VV Cephei in the sky
VV Cephei lies in Cepheus. With a declination of +63° 37.5', it is visible from the entire Northern Hemisphere and from the Southern Hemisphere down to about latitude 26° S. Observers poleward of latitude 26° N see it as circumpolar: it never sets. It is bright enough to see with the naked eye under dark skies. It is highest in the sky at local midnight around September, which makes the weeks around that month the best time to observe it.
Tabulated data for VV Cephei
Astrometry and spectroscopy
| Right Ascension (J2000) | 329.16308957° (21h 56.7m) |
| Declination (J2000) | 63.62555045° (+63° 37.5') |
| Galactic Longitude | 104.91910736° |
| Galactic Latitude | 7.04608788° |
| Proper motion RA | -1.07 mas/yr |
| Proper motion Dec | -0.42 mas/yr |
| Parallax | 1.00 ± 0.11 mas |
| Spectral Type | M2Ibep+B2?ep_sh |
| Radial Velocity | -18.70 km/s |
Photometry
| Band | Magnitude | Abs. Mag. |
|---|---|---|
| U | 7.03 | -2.96 |
| B | 6.65 | -3.34 |
| V | 4.90 | -5.09 |
| R | 3.19 | -6.80 |
| I | 1.85 | -8.14 |
| J | 1.23 | -8.77 |
| H | 0.37 | -9.62 |
| K | -0.00 | -9.99 |
Colour index B-V: +1.75
Derivations
- Heliocentric distance: 996.71 pc (3,251 light years) (10.7% margin of error)
- Absolute visual magnitude: -5.09
- Transverse velocity: 5.4 km/s
- Space velocity relative to the Sun: 19.5 km/s
- Galactic position (X, Y, Z): -254.7 pc, 955.8 pc, 122.3 pc
- Galactic velocity (U, V, W): 9.8 km/s, -16.8 km/s, -0.8 km/s
Data: Extended Hipparcos Compilation (XHIP) and SIMBAD.