RW Cephei, an orange supergiant star in Cepheus
RW Cephei is an orange supergiant star in the constellation Cepheus. At 28,610 light years away, it shines at an apparent visual magnitude of 6.65.
RW Cephei (HIP 110504)
RW Cephei is an orange supergiant star in the constellation Cepheus. At 28,610 light years away, it shines at an apparent visual magnitude of 6.65. It is moving through the Galaxy at a speed of 199.9 km/s relative to the Sun.
Sky position: RA 22h 23.1m, Dec +55° 57.8'
Common designations: RW Cephei, HD 212466, Gaia DR3 2005992002061917312, HIP 110504
RW Cephei has the spectral type K2_0-Ia. K-type stars are orange stars with surface temperatures of about 3,900 to 5,300 K. Their spectra are rich in neutral metal lines and, in the cooler examples, molecular bands. Its luminosity class I marks it as a supergiant, among the most luminous and largest stars known.
How to find RW Cephei in the sky
RW Cephei lies in Cepheus. With a declination of +55° 57.8', it is visible from the entire Northern Hemisphere and from the Southern Hemisphere down to about latitude 34° S. Observers poleward of latitude 34° N see it as circumpolar: it never sets. It is just beyond naked-eye visibility; binoculars will show it easily. 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 RW Cephei
Astrometry and spectroscopy
| Right Ascension (J2000) | 335.77923003° (22h 23.1m) |
| Declination (J2000) | 55.96322899° (+55° 57.8') |
| Galactic Longitude | 103.20478897° |
| Galactic Latitude | -1.12047640° |
| Proper motion RA | -3.61 mas/yr |
| Proper motion Dec | -2.88 mas/yr |
| Parallax | 0.11 ± 0.03 mas |
| Spectral Type | K2_0-Ia |
| Radial Velocity | -56.00 km/s |
Photometry
| Band | Magnitude | Abs. Mag. |
|---|---|---|
| U | 11.25 | -3.47 |
| B | 8.87 | -5.85 |
| V | 6.65 | -8.07 |
| R | 4.94 | -9.78 |
| I | 3.78 | -10.94 |
| J | 2.83 | -11.89 |
| H | 2.22 | -12.50 |
| K | 1.88 | -12.84 |
Colour index B-V: +2.22
Derivations
- Heliocentric distance: 8,771.93 pc (28,610 light years) (30.0% margin of error)
- Absolute visual magnitude: -8.07
- Transverse velocity: 191.9 km/s
- Space velocity relative to the Sun: 199.9 km/s
- Galactic position (X, Y, Z): -2003.4 pc, 8538.4 pc, -171.5 pc
- Galactic velocity (U, V, W): 198.7 km/s, -11.3 km/s, -19.5 km/s
Data: Extended Hipparcos Compilation (XHIP) and SIMBAD.