V381 Cephei, a red supergiant star in Cepheus
V381 Cephei is a red supergiant star in the constellation Cepheus. At 5,881 light years away, it shines at an apparent visual magnitude of 5.75.
V381 Cephei (HIP 105259)
V381 Cephei is a red supergiant star in the constellation Cepheus. At 5,881 light years away, it shines at an apparent visual magnitude of 5.75. It is moving through the Galaxy at a speed of 45.6 km/s relative to the Sun.
Sky position: RA 21h 19.3m, Dec +58° 37.4'
Common designations: V381 Cephei, HR 8164, HD 203338, Gaia DR3 2191213153886504704, HIP 105259
V381 Cephei has the spectral type M1Ibep. 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 V381 Cephei in the sky
V381 Cephei lies in Cepheus. With a declination of +58° 37.4', it is visible from the entire Northern Hemisphere and from the Southern Hemisphere down to about latitude 31° S. Observers poleward of latitude 31° 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 V381 Cephei
Astrometry and spectroscopy
| Right Ascension (J2000) | 319.81535506° (21h 19.3m) |
| Declination (J2000) | 58.62350674° (+58° 37.4') |
| Galactic Longitude | 98.18366952° |
| Galactic Latitude | 6.35673069° |
| Proper motion RA | -1.89 mas/yr |
| Proper motion Dec | -4.75 mas/yr |
| Parallax | 0.55 ± 0.18 mas |
| Spectral Type | M1Ibep |
| Radial Velocity | -13.11 km/s |
Photometry
| Band | Magnitude | Abs. Mag. |
|---|---|---|
| U | 7.09 | -4.19 |
| B | 7.09 | -4.19 |
| V | 5.75 | -5.53 |
| R | 4.26 | -7.02 |
| I | 2.93 | -8.35 |
| J | 1.98 | -9.30 |
| H | 0.98 | -10.30 |
| K | 0.81 | -10.48 |
Colour index B-V: +1.34
Derivations
- Heliocentric distance: 1,803.10 pc (5,881 light years) (32.3% margin of error)
- Absolute visual magnitude: -5.53
- Transverse velocity: 43.7 km/s
- Space velocity relative to the Sun: 45.6 km/s
- Galactic position (X, Y, Z): -255.1 pc, 1773.8 pc, 199.6 pc
- Galactic velocity (U, V, W): 41.5 km/s, -5.3 km/s, -18.1 km/s
Data: Extended Hipparcos Compilation (XHIP) and SIMBAD.